阅读说明：本技术 喷墨印刷封装型量子点制造方法、光转换单元及显示面板 (Manufacturing method of inkjet printing packaging type quantum dot, light conversion unit and display panel ) 是由 陈学仕 于 2020-04-08 设计创作，主要内容包括：本发明主要提出一种喷墨印刷封装型量子点的制造方法以及具有前述喷墨印刷封装型量子点的光转换单元。该光转换单元包括：一透光基板、具有M×N个容置槽的一光转换器携载层、利用一第一量子点溶液制成的(M×N)/3个第一封装量子点微米结构、以及利用一第二量子点溶液制成的(M×N)/3个第二封装量子点微米结构。在令该透光基板具有一疏水性表面的情况下,可利用一喷墨印刷喷头将该第一量子点溶液和该第二量子点溶液以液滴的形式填注于各所述容置槽中,从而在对应的容置槽中形成该第一封装量子点微米结构与该第二封装量子点微米结构。实验结果显示,使用该光转换单元的一微发光二极管显示面板,其所表现出的色域范围接近为NTSC标准色域范围的110％。(The invention mainly provides a manufacturing method of an inkjet printing encapsulated quantum dot and a light conversion unit with the inkjet printing encapsulated quantum dot. The light conversion unit includes: a transparent substrate, a light converter carrying layer with MXN containing slots, an (MXN)/3 first packaged quantum dot microstructures prepared by a first quantum dot solution, and an (MXN)/3 second packaged quantum dot microstructures prepared by a second quantum dot solution. Under the condition that the transparent substrate has a hydrophobic surface, the first quantum dot solution and the second quantum dot solution can be filled in each accommodating groove in a droplet form by using an ink jet printing nozzle, so that the first encapsulated quantum dot microstructure and the second encapsulated quantum dot microstructure are formed in the corresponding accommodating grooves. Experimental results show that a micro led display panel using the light conversion unit exhibits a color gamut range close to 110% of the NTSC standard color gamut range.)

1. The manufacturing method of the ink-jet printing encapsulation type quantum dot is characterized by comprising the following steps:

providing a substrate with a hydrophobic surface and a quantum dot solution comprising at least one quantum dot, an aqueous solvent and a solute with cohesive force;

dropping the quantum dot solution on the hydrophobic surface of the substrate by using an ink jet printing nozzle so as to form at least one drop on the hydrophobic surface;

and performing a drying process on the droplet, so that the volume of the droplet is continuously reduced along with the increase of the drying process time, and the droplet is further converted into a packaged quantum dot micron structure.

2. The method as claimed in claim 1, wherein the encapsulated quantum dot microstructure comprises at least one encapsulant encapsulating at least one quantum dot.

3. The method for manufacturing inkjet printing encapsulated quantum dots according to claim 1, wherein the solute with cohesive force has a concentration ranging from 0.5 wt% to 5.5 wt%, and the material thereof is any one of the following: lithium chloride, sodium chloride, potassium chloride, lithium iodide, sodium iodide, potassium iodide, lithium bromide, sodium bromide, or potassium bromide.

4. The method as claimed in claim 1, wherein a surfactant is further added to the quantum dot solution to reduce satellite droplets of the droplets ejected from the inkjet print head.

5. The method of claim 1, wherein the quantum dot has a hydrophilic surface modification layer, and the hydrophilic surface modification layer is any one of the following: red light quantum dots, green light quantum dots, or the blue light quantum dots.

6. A light conversion unit, comprising:

a light-transmitting substrate;

a light converter carrying layer formed on a setting surface of the light-transmitting substrate and made of a metal material or a metal oxide;

a plurality of first openings formed on the light converter carrying layer, wherein the plurality of first openings are arranged in M/3 rows and N/3 columns; wherein, each first opening and the setting surface of the transparent substrate form a first containing groove together;

a plurality of second openings formed on the light converter carrying layer, wherein the plurality of second openings are arranged in M/3 rows and N/3 columns; wherein, each second opening and the setting surface of the transparent substrate form a second containing groove together;

a plurality of third openings formed on the light converter carrying layer, wherein the plurality of third openings are arranged in M/3 rows and N/3 columns; wherein, each third opening and the setting surface of the transparent substrate form a third containing groove together;

a first quantum dot solution, including at least one red light quantum dot, an aqueous solvent and a first solute, wherein the first solute has a cohesive force, and the first quantum dot solution is injected into each of the first receiving grooves in the form of a first droplet by using an inkjet printing head; and

a second quantum dot solution, including at least one green quantum dot, the water solvent and a second solute, wherein the second solute also has the cohesive force, and the second quantum dot solution is injected into each of the second receiving grooves in the form of a second droplet by using the inkjet printing head;

wherein, when the setting surface is a hydrophobic surface, the cohesive force of the first solute and the second solute is greater than an outflow driving force derived from a coffee ring effect, the first droplet and the second droplet are dried on the setting surface, that is, a first encapsulated quantum dot microstructure including at least one red light quantum dot and a second encapsulated quantum dot microstructure including at least one green light quantum dot are respectively formed in each of the first accommodating grooves and each of the second accommodating grooves;

wherein M and N are positive integers.

7. The light conversion unit of claim 6, further comprising a third quantum dot solution comprising at least one blue quantum dot, the aqueous solvent and a third solute, wherein the third solute also has the cohesive force, and the third quantum dot solution is injected into each of the third receiving grooves in the form of a third droplet by the inkjet print head, so as to form a third encapsulated quantum dot microstructure comprising at least one blue quantum dot in each of the third receiving grooves after drying.

8. The light conversion unit of claim 6, wherein the metal material is any one of: gold, copper, aluminum, silver, chromium, molybdenum, titanium, indium, antimony, a metal alloy of any two of the foregoing, or a metal alloy of any two or more of the foregoing.

9. The light conversion unit of claim 6, wherein the metal oxide is any one of: copper oxide, aluminum oxide, silver oxide, chromium oxide, molybdenum oxide, titanium oxide, indium oxide, antimony oxide, a composite of any two of the foregoing, or a composite of any two or more of the foregoing.

10. The light conversion unit of claim 7, wherein the first encapsulated quantum dot microstructure comprises at least one first encapsulant encapsulating at least one of the red quantum dots, the second encapsulated quantum dot microstructure comprises at least one second encapsulant encapsulating at least one of the green quantum dots, and the third encapsulated quantum dot microstructure comprises at least one third encapsulant encapsulating at least one of the green quantum dots.

11. The light conversion unit of claim 7, further comprising:

an encapsulating material filled in each of the first receiving grooves, the second receiving grooves, and the third receiving grooves for encapsulating the first encapsulated quantum dot microstructures in the first receiving grooves, the second encapsulated quantum dot microstructures in the second receiving grooves, and the third encapsulated quantum dot microstructures in the third receiving grooves; and

and the water-gas barrier layer is arranged on the optical converter carrying layer and covers the plurality of first accommodating grooves, the plurality of second accommodating grooves and the plurality of third accommodating grooves.

12. The light conversion unit of claim 6, wherein the first solute, the second solute and the third solute are any one of: lithium chloride, sodium chloride, potassium chloride, lithium iodide, sodium iodide, potassium iodide, lithium bromide, sodium bromide, or potassium bromide.

13. The light conversion unit of claim 6, wherein a surfactant is further added to the first quantum dot solution, the second quantum dot solution and the third quantum dot solution to reduce satellite droplets of the first droplet, the second droplet and the third droplet ejected from the inkjet print head.

14. The light conversion unit of claim 6, wherein the red, green and blue quantum dots each have a hydrophilic surface modification layer, and the first, second and third solutes each have a concentration in a range of 0.5 wt% to 5.5 wt%.

15. A micro light emitting diode display panel, comprising:

a substrate;

m × N micro light-emitting diodes disposed on the substrate;

a light-transmitting substrate arranged on the MXN micro light-emitting diodes and the substrate;

a light converter carrying layer formed on a setting surface of the light-transmitting substrate and made of a metal material or a metal oxide;

a plurality of first openings formed on the light converter carrying layer, wherein the plurality of first openings are arranged in M/3 rows and N/3 columns; wherein, each first opening and the setting surface of the transparent substrate form a first containing groove together;

a plurality of second openings formed on the light converter carrying layer, wherein the plurality of second openings are arranged in M/3 rows and N/3 columns; wherein, each second opening and the setting surface of the transparent substrate form a second containing groove together;

a plurality of third openings formed on the light converter carrying layer, wherein the plurality of third openings are arranged in M/3 rows and N/3 columns; wherein, each third opening and the setting surface of the transparent substrate form a third containing groove together;

a first quantum dot solution, including at least one red light quantum dot, an aqueous solvent and a first solute, wherein the first solute has a cohesive force, and the first quantum dot solution is injected into each of the first receiving grooves in the form of a first droplet by using an inkjet printing head; and

a second quantum dot solution, including at least one green quantum dot, the water solvent and a second solute, wherein the second solute also has the cohesive force, and the second quantum dot solution is injected into each of the second receiving grooves in the form of a second droplet by using the inkjet printing head;

under the condition that the setting surface is a hydrophobic surface so that the concentration force of the first solute and the second solute is greater than an outflow driving force derived from a coffee ring effect, drying the first liquid drop and the second liquid drop on the setting surface, namely respectively forming a first encapsulated quantum dot microstructure coated with at least one red light quantum dot and a second encapsulated quantum dot microstructure coated with at least one green light quantum dot in each first accommodating groove and each second accommodating groove;

wherein M and N are positive integers.

16. The micro led display panel of claim 15, further comprising: and a third quantum dot solution including at least one blue quantum dot, water and a third solute, wherein the third solute also has the cohesive force, and the third quantum dot solution is respectively injected into each of the third receiving grooves in a third droplet form by using the inkjet printing head, so that a third encapsulated quantum dot microstructure in which at least one blue quantum dot is encapsulated is respectively formed in each of the third receiving grooves after drying.

17. The micro led display panel of claim 16, wherein the first encapsulated quantum dot microstructure comprises at least one first encapsulant encapsulating at least one of the red quantum dots, the second encapsulated quantum dot microstructure comprises at least one second encapsulant encapsulating at least one of the green quantum dots, and the third encapsulated quantum dot microstructure comprises at least one third encapsulant encapsulating at least one of the green quantum dots.

18. The micro-led display panel of claim 16, wherein the first solute, the second solute and the third solute are any one of the following: lithium chloride, sodium chloride, potassium chloride, lithium iodide, sodium iodide, potassium iodide, lithium bromide, sodium bromide, or potassium bromide.

19. The micro led display panel of claim 16, wherein the red, green and blue quantum dots have a hydrophilic surface modification layer, and the first, second and third solutes have a concentration ranging from 1 wt% to 5 wt%.

20. The micro led display panel of claim 16, wherein a surfactant is further added to the first, second and third quantum dot solutions to reduce satellite droplets of the first, second and third droplets ejected by the inkjet print head.

Technical Field

The invention relates to the technical field of micro light-emitting diode display panels, in particular to a manufacturing method of inkjet printing packaging type quantum dots, a light conversion unit with the inkjet printing packaging type quantum dots and a micro light-emitting diode display panel.

Background

As is known, conventional flat panel displays include a Liquid Crystal Display (LCD) and a plasma display, wherein the LCD is a non-self-luminous flat panel display (non-self-emissive flat panel display) having a structure including at least: the white light LED backlight module comprises a white light LED backlight module, a liquid crystal panel and a color filter. A driving circuit is used for controlling the white light LED backlight module to emit white backlight, so that the white backlight is converted into red light, green light and blue light after passing through the liquid crystal panel and then the color filter, and the red light, the green light and the blue light are used as a red sub-pixel, a green sub-pixel and a blue sub-pixel displayed on a screen. According to statistics, the LCD using the white LED backlight module can exhibit an optimal color gamut (color gamut) of only 72% NTSC, and the brightness of the LCD cannot be increased to over 1000nits, so the image and color recognition of the LCD in outdoor environment is too low.

Unlike LCD displays, Light Emitting Diode (LED) displays and Organic Light Emitting Diode (OLED) displays are Self-luminous flat panel displays. It is worth mentioning that Mini LED, also known as "sub-millimeter light emitting diode", was first proposed by the wafer photovoltaics (EPISTAR Corporation) as an LED with a die having a diagonal length between 50 and 60 microns. Micro LEDs are a new generation of Micro LED technology, in which LED dies are further miniaturized to have a diagonal length of less than 50 microns. Because sub-millimeter LEDs and micro-LEDs have the advantages of low power consumption, fast response time, high brightness, high contrast, and easy addressing to drive light emission, LED displays using sub-millimeter LEDs or micro-LEDs as arrayed spontaneous photonic pixels are rapidly evolving and have a high potential to replace conventional LCD displays.

At present, the biggest difficulty encountered in the fabrication of RGB micro LED displays is the Mass transfer (Mass transfer). Therefore, manufacturers have proposed to fabricate M × N blue micro LED chips on only one substrate by Photolithography (Photolithography), and then dispose a quantum dot light conversion unit above the M × N blue micro LED chips, so as to convert the blue light emitted from the M × N blue micro LED chips into red light, green light, and blue light as red sub-pixels, green sub-pixels, and blue sub-pixels displayed on a screen.

Chinese patent publication No. CN108664165A discloses a display panel with quantum dot light conversion units. Fig. 1 shows a side sectional view of a display panel with quantum dot light conversion units disclosed in chinese patent publication No. CN 108664165A. As shown in fig. 1, the display panel 1' having the quantum dot light conversion unit includes: a first substrate 10 ', M × N blue micro LED chips 20 ', a second substrate 60 ', and a light shielding layer 30 ', wherein the M × N blue micro LED chips 20 ' are formed on the first substrate 10 ', and the second substrate 60 ' is disposed on the M × N blue micro LED chips 20 ' and the first substrate 10 '. It is noted that the light shielding layer 30 'has M × N through holes 31', and the M × N through holes 31 'correspond to the M × N blue micro LED chips 20', respectively. In more detail, M × N/3 of the M × N through holes 31 'are filled with a red quantum dot material 81', and M × N/3 of the through holes 31 'are filled with a green quantum dot material 82'. And the remaining M × N/3 vias 31' are not filled with any quantum dot material.

It should be noted that, as can be seen from the foregoing description, chinese patent publication No. CN108664165A discloses that the light-shielding layer 30 ' is made of an organic material (e.g., black photoresist), and the second substrate 60 ', the light-shielding layer 30 ', the red quantum dot material 81 ' filled in M × N/3 through holes 31 ', and the green quantum dot material 82 ' filled in M × N/3 through holes 31 ' form a quantum dot light conversion unit. In general, the thickness of the light-shielding layer 30' must be 5 μm or more. However, practical experience has shown that when the thickness is greater than 5 μ M, the light shielding layer 30 ' begins to be distorted, and the M × N through holes 31 ' cannot be precisely aligned with the M × N blue micro LED chips 20 '.

On the other hand, practical experience also shows that when the red quantum dot material 81 'and the green quantum dot material 82' are quantitatively filled into each through hole 31 ', the filling amount between two adjacent through holes 31' is often uneven. It should be understood that in the case that two adjacent through holes 31 'accommodate different amounts of quantum dot materials, the display panel 1' with the quantum dot light conversion unit does not necessarily perform as well as expected in terms of color saturation.

As can be seen from the foregoing description, the display panel 1' with quantum dot light conversion units proposed in the prior art still has the points that need to be improved. Therefore, the present invention provides a method for manufacturing inkjet printing encapsulated quantum dots, a light conversion unit and a micro light emitting diode display panel having the inkjet printing encapsulated quantum dots.

Disclosure of Invention

The invention mainly aims to provide a manufacturing method of an inkjet printing encapsulated quantum dot and a light conversion unit with the inkjet printing encapsulated quantum dot. The basic structure of the light conversion unit with the inkjet printing packaging type quantum dots comprises a light-transmitting substrate, a light converter carrying layer with M multiplied by N containing grooves, an (M multiplied by N)/3 first packaging quantum dot micron structure made of a first quantum dot solution, and an (M multiplied by N)/3 second packaging quantum dot micron structure made of a second quantum dot solution. Under the condition that the transparent substrate has a hydrophobic surface, the first quantum dot solution and the second quantum dot solution can be filled in each accommodating groove in a droplet form by using an ink jet printing nozzle, so that the first encapsulated quantum dot microstructure and the second encapsulated quantum dot microstructure are formed in the corresponding accommodating grooves. Experimental results show that a micro led display panel using the light conversion unit exhibits a color gamut range close to 110% of the NTSC standard color gamut range.

To achieve the above object, the present invention provides an embodiment of a method for manufacturing inkjet printing encapsulated quantum dots, which includes the following steps:

providing a substrate with a hydrophobic surface and a quantum dot solution comprising at least one quantum dot, an aqueous solvent and a solute with cohesive force;

dropping the quantum dot solution on the hydrophobic surface of the substrate by using an ink jet printing nozzle so as to form at least one drop on the hydrophobic surface;

and performing a drying process on the droplet, so that the volume of the droplet is continuously reduced along with the increase of the drying process time, and the droplet is further converted into a packaged quantum dot micron structure.

To achieve the above object, the present invention provides an embodiment of the light conversion unit with inkjet printing encapsulated quantum dots, which includes:

a light-transmitting substrate;

a light converter carrying layer formed on a setting surface of the light-transmitting substrate and made of a metal material or a metal oxide;

a plurality of first openings formed on the light converter carrying layer, wherein the plurality of first openings are arranged in M/3 rows and N/3 columns; wherein, each first opening and the setting surface of the transparent substrate form a first containing groove together;

a plurality of second openings formed on the light converter carrying layer, wherein the plurality of second openings are arranged in M/3 rows and N/3 columns; wherein, each second opening and the setting surface of the transparent substrate form a second containing groove together;

a plurality of third openings formed on the light converter carrying layer, wherein the plurality of third openings are arranged in M/3 rows and N/3 columns; wherein, each third opening and the setting surface of the transparent substrate form a third containing groove together;

a first quantum dot solution, including at least one red light quantum dot, an aqueous solvent and a first solute, wherein the first solute has a cohesive force, and the first quantum dot solution is injected into each of the first receiving grooves in the form of a first droplet by using an inkjet printing head; and

a second quantum dot solution, including at least one green quantum dot, the water solvent and a second solute, wherein the second solute also has the cohesive force, and the second quantum dot solution is injected into each of the second receiving grooves in the form of a second droplet by using the inkjet printing head;

wherein, when the setting surface is a hydrophobic surface, such that the cohesive force between the first solute and the second solute is greater than an outflow Driving force (Driving force of the coffee ring effect) derived from the coffee ring effect, the first droplet and the second droplet are dried on the setting surface, i.e., a first encapsulated quantum dot microstructure including at least one red quantum dot and a second encapsulated quantum dot microstructure including at least one green quantum dot are formed in each of the first receiving grooves and each of the second receiving grooves, respectively;

wherein M and N are both positive integers.

In a practical embodiment, the light conversion unit of the present invention further includes a third quantum dot solution including at least one blue quantum dot, the water solvent and a third solute, wherein the third solute also has the cohesive force, and the third quantum dot solution is respectively injected into each of the third receiving grooves in the form of a third droplet by using the inkjet print head, so as to form a third encapsulated quantum dot microstructure including at least one blue quantum dot in each of the third receiving grooves after drying.

In the aforementioned embodiments of the light conversion unit of the present invention, the first encapsulated quantum dot microstructure comprises at least one first encapsulant encapsulating at least one red quantum dot, the second encapsulated quantum dot microstructure comprises at least one second encapsulant encapsulating at least one green quantum dot, and the third encapsulated quantum dot microstructure comprises at least one third encapsulant encapsulating at least one green quantum dot.

In the aforementioned embodiments of the light conversion unit of the present invention, the first solute, the second solute and the third solute may be any one of the following: lithium chloride (LiCl), sodium chloride (NaCl), potassium chloride (KCl), lithium iodide (LiI), sodium iodide (NaI), potassium iodide (KI), lithium bromide (LiBr), sodium bromide (NaBr), or potassium bromide (KBr).

In the embodiment of the light conversion unit of the present invention, a surfactant is further added to the first quantum dot solution, the second quantum dot solution and the third quantum dot solution to reduce satellite droplets of the first droplet, the second droplet and the third droplet ejected from the inkjet print head.

In the aforementioned embodiments of the light conversion unit of the present invention, the first solute, the second solute and the second solute each have a concentration ranging from 0.5 wt% to 5.5 wt%.

In the aforementioned embodiment of the light conversion unit of the invention, the red light quantum dot, the green light quantum dot and the blue light quantum dot all have a Hydrophilic surface modification layer.

Further, to achieve the above object, the present invention also provides an embodiment of the micro led display panel, which includes:

a substrate;

m × N micro light-emitting diodes disposed on the substrate;

a light-transmitting substrate arranged on the MXN micro light-emitting diodes and the substrate;

a light converter carrying layer formed on a setting surface of the light-transmitting substrate and made of a metal material or a metal oxide;

a plurality of first openings formed on the light converter carrying layer, wherein the plurality of first openings are arranged in M/3 rows and N/3 columns; wherein, each first opening and the setting surface of the transparent substrate form a first containing groove together;

a plurality of second openings formed on the light converter carrying layer, wherein the plurality of second openings are arranged in M/3 rows and N/3 columns; wherein, each second opening and the setting surface of the transparent substrate form a second containing groove together;

a plurality of third openings formed on the light converter carrying layer, wherein the plurality of third openings are arranged in M/3 rows and N/3 columns; wherein, each third opening and the setting surface of the transparent substrate form a third containing groove together;

a first quantum dot solution, including at least one red light quantum dot, an aqueous solvent and a first solute, wherein the first solute has a cohesive force, and the first quantum dot solution is injected into each of the first receiving grooves in the form of a first Droplet (Droplet) by using an inkjet printing head; and

a second quantum dot solution, including at least one green quantum dot, the water solvent and a second solute, wherein the second solute also has the cohesive force, and the second quantum dot solution is injected into each of the second receiving grooves in the form of a second droplet by using the inkjet printing head;

wherein, when the setting surface is a hydrophobic surface and the cohesive force of the first solute and the second solute is greater than an outflow Driving force (Driving force for impinging-bound flow) derived from Coffee ring effect (Coffee ring effect), the first droplet and the second droplet are dried on the setting surface, that is, a first encapsulated quantum dot microstructure including at least one red quantum dot and a second encapsulated quantum dot microstructure including at least one green quantum dot are respectively formed in each of the first receiving grooves and each of the second receiving grooves;

wherein M and N are positive integers.

In a practical embodiment, the micro led display panel of the present invention further includes a third quantum dot solution including at least one blue quantum dot, the water solvent and a third solute, wherein the third solute also has the cohesive force, and the third quantum dot solution is respectively injected into each of the third receiving grooves in the form of a third droplet by using the inkjet print head, so as to form a third encapsulated quantum dot microstructure including at least one blue quantum dot in each of the third receiving grooves after drying.

The invention is described in detail below with reference to the drawings and specific examples, but the invention is not limited thereto.

Drawings

FIG. 1 shows a display panel with quantum dot light conversion units disclosed in Chinese patent publication No. CN 108664165A;

fig. 2 shows a flow chart of a method for manufacturing inkjet printing encapsulated quantum dots according to the present invention;

fig. 3 is a perspective view of a light conversion unit having inkjet printing encapsulated quantum dots and a micro light emitting diode display panel using the same according to the present invention;

fig. 4 shows an exploded perspective view of a light conversion unit with inkjet printed encapsulated quantum dots according to the present invention;

fig. 5 shows a side cross-sectional view of a light conversion unit with inkjet printed encapsulated quantum dots according to the present invention;

fig. 6A, 6B and 6C show schematic flow diagrams of a first experiment;

FIG. 7 shows an image of the evolution over time of a first test droplet into at least one salt crystal, taken using bright field and dark field fluorescence microscopy;

fig. 8A, 8B and 8C show schematic flow diagrams of a second experiment;

FIG. 9 shows an image of the evolution over time of a second test droplet into at least one salt crystal, taken using bright field and dark field fluorescence microscopy;

fig. 10 shows optical microscopy image plots of X Y first encapsulated quantum dot microstructures and X Y second encapsulated quantum dot microstructures;

fig. 11 is a perspective view illustrating a light conversion unit having inkjet printing encapsulated quantum dots and a micro light emitting diode display panel using the same according to the present invention;

fig. 12 shows an exploded perspective view of a light conversion unit with inkjet printed encapsulated quantum dots according to the present invention;

FIG. 13 shows M/3 XN/3 first encapsulated quantum dot microstructures, M/3 XN/3 second encapsulated quantum dot microstructures, and M/3 XN/3 third encapsulated quantum dot microstructures;

FIG. 14 shows a CIE 1931 chromaticity diagram of the micro LED display panel shown in FIG. 12; and

fig. 15 shows a side cross-sectional view of a light conversion unit with inkjet printed encapsulated quantum dots of the present invention as shown in fig. 12.

Wherein the reference numerals

The invention

1: micro light emitting diode display panel

10 base plate

11 micro light emitting diode

12 light-transmitting substrate

121: setting surface

Optical converter carrying layer 13

14 moisture barrier layer

15 packaging material

RQ first encapsulated quantum dot microstructure

GQ-second encapsulated quantum dot microstructure

BQ-third encapsulated quantum dot microstructure

A1 first accommodation groove

A2 second accommodation groove

A3 third accommodation groove

O1 first opening

O2 second opening

O3 third opening

S1 first droplet

S2 second droplet

S3 third droplet

T1 first test droplet

T10 aqueous solvent

T11 Quantum dots

T12 solute

T2 second test droplet

T20 aqueous solvent

T21 Quantum dots

T22 solute

NC (numerical control) salt-encapsulated quantum dot micron structure

S1-S3

Prior Art

Display panel with quantum dot light conversion unit

10' a first substrate

20' blue light micro LED chip

30' light shielding layer

31' through hole

60' second substrate

81' red light quantum dot material

82' green light quantum point material

Detailed Description

In order to more clearly describe the method for manufacturing the inkjet printing encapsulated quantum dots, the light conversion unit having the inkjet printing encapsulated quantum dots, and the micro light emitting diode display panel, preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Referring to fig. 2, a flow chart of a method for manufacturing an inkjet printing encapsulated quantum dot according to the present invention is shown. As shown in fig. 2, a method for manufacturing inkjet printing encapsulated quantum dots according to the present invention includes:

step S1, providing a substrate with a hydrophobic surface and a quantum dot solution including at least one quantum dot, an aqueous solvent and a solute with cohesive force;

step S2, dropping the quantum dot solution on the hydrophobic surface of the substrate by using an inkjet printing nozzle, thereby forming at least one drop on the hydrophobic surface; and

in step S3, a drying process is performed on the droplet, so that the volume of the droplet is continuously decreased with the increase of a drying process time, and the droplet is transformed into a packaged quantum dot microstructure.

Continuously, a light conversion unit and a micro light emitting diode display panel having inkjet printing encapsulated quantum dots completed by the method for manufacturing inkjet printing encapsulated quantum dots of the present invention will be described below.

First embodiment

Fig. 3 is a perspective view of a light conversion unit having inkjet printing encapsulated quantum dots and a micro light emitting diode display panel using the same according to the present invention. As shown in fig. 3, the micro led display panel 1 of the present invention mainly includes: a substrate 10, mxn micro-leds 11, and a light conversion unit having inkjet printing packaged quantum dots. Further, fig. 4 shows a perspective exploded view of the light conversion unit with inkjet printed encapsulated quantum dots of the present invention, and fig. 5 shows a side cross-sectional view of the light conversion unit with inkjet printed encapsulated quantum dots of the present invention. In the case that the micro led 11 is a blue micro led, the present invention makes the light conversion unit with inkjet printing encapsulation quantum dots (hereinafter referred to as "light conversion unit") include: a transparent substrate 12, a light converter carrying layer 13, (M × N)/3 first encapsulated quantum dot microstructures RQ made using a first quantum dot solution, and (M × N)/3 second encapsulated quantum dot microstructures GQ made using a second quantum dot solution.

More specifically, the transparent substrate 12 is disposed on the M × N micro light emitting diodes 11 and the substrate 10, and the material of the transparent substrate may be any one of the following materials: polyethylene terephthalate (PET), polyethersulfone resin (poly (ether sulfones), PES), or glass. On the other hand, the light converter carrying layer 13 is formed on a mounting surface 121 of the transparent substrate 12, and has a good light shielding property and a thickness of at least 1 μm. Thus, in a possible embodiment, the optical converter carrying layer 13 may be made of a metal material, such as: gold, copper, aluminum, silver, chromium, molybdenum, titanium, indium, antimony, a metal alloy of any two of the foregoing, or a metal alloy of any two or more of the foregoing. Also, in another possible embodiment, the light converter carrying layer 13 may also be made of an oxide of the aforementioned metal materials, including: copper oxide, aluminum oxide, silver oxide, chromium oxide, molybdenum oxide, titanium oxide, indium oxide, antimony oxide, a composite of any two of the foregoing, or a composite of any two or more of the foregoing.

With continued reference to fig. 3, 4 and 5. According to the design of the present invention, the light converter carrying layer 13 is formed with a plurality of first openings O1, a plurality of second openings O2 and a plurality of third openings O3. The plurality of first openings O1 are arranged in M/3 rows and N/3 columns, and each of the first openings O1 and the installation surface 121 of the transparent substrate 12 together form a first accommodation groove a 1. Moreover, the plurality of second openings O2 are arranged in M/3 rows and N/3 columns, and each of the second openings O2 and the mounting surface 121 of the transparent substrate 12 together form a second receiving cavity a 2. On the other hand, the plurality of third openings O3 are arranged in M/3 rows and N/3 columns, and each of the third openings O3 and the mounting surface 121 of the transparent substrate 12 together form a third receiving groove A3. In brief, in the present invention, M × N receiving slots are formed on the light converter carrying layer 13, and the M × N receiving slots include M/3 × N/3 first receiving slots a1, M/3 × N/3 second receiving slots a2, and M/3 × N/3 third receiving slots A3.

The present invention is technically characterized in that inkjet-printed encapsulated quantum dots (inkjet-printed encapsulated quantum dots) are used as a main light converter of a light conversion unit. Therefore, the present invention mixes at least one red light quantum dot, an aqueous solvent and a first solute to form a first quantum dot solution, wherein the first solute has a cohesive force and a concentration ranging from 0.5 wt% to 5.5 wt%. It should be noted that, in order to increase the solubility of the red light quantum dot in the aqueous solvent, the red light quantum dot may be provided with a Hydrophilic surface modification layer (Hydrophilic surface modification layer). For example, red light quantum dots that originally had a layer of oleic acid ligands (OLEI acid ligands) were modified to a layer of 3-mercaptopropionic acid (MPA) using ligand exchange techniques. Continuously, as shown in fig. 4, the first quantum dot solution may be respectively injected into each of the first accommodating grooves a1 in the form of a first droplet S1 by using an inkjet print head. Then, when the setting surface 121 is a hydrophobic surface, the Cohesive force (coherent force) of the first solute of the first droplet S1 dropped on the hydrophobic surface is greater than an outflow Driving force (Driving force for impacting out-bound flow) derived from Coffee ring effect (Coffee ring effect).

Additionally, the coffee ring effect refers to that when the liquid drops dry on a solid surface, a plurality of rings gradually deepen from inside to outside. In more detail, the Coffee Ring Effect (CRE) is the tendency of a solute to segregate at the edge of a droplet that drips onto the surface of a substrate. Research data indicate that the coffee ring effect often occurs in drop cast films because solvent evaporation during assembly of the film stimulates capillary flow within the drop, displacing solute particles onto the three-phase contact line. As a result, the solute particles are susceptible to the radially outward flow of fluid that drives the coffee ring effect, accelerating particle accumulation at the dry film boundary, thus forming a coffee ring.

Therefore, after the first quantum dot solution is injected into the first receiving cavity a1 in the form of the first droplet S1 by using the inkjet printing head, in order to prevent the first solute and the red quantum dots from gradually moving away from the center of the first droplet S1 due to the effect of the coffee ring effect, the invention particularly treats the disposing surface 121 of the transparent substrate 12 as a hydrophobic surface, so that the cohesive force of the first solute of the first droplet S1 is greater than the outflow driving force derived from the coffee ring effect. In this case, it is only necessary to perform a drying process on the first droplet S1 in each of the first receiving grooves a1, such that a first quantum dot micron structure RQ including at least one red quantum dot is generated in each of the first receiving grooves a 1.

In addition, the invention mixes at least one green light quantum dot, the water solvent and a second solute into a second quantum dot solution, wherein the second solute also has the cohesive force and has a concentration ranging from 0.5 wt% to 5.5 wt%. Similarly, the green quantum dot has a Hydrophilic surface modification layer (Hydrophilic surface modification layer), and the second quantum dot solution can be injected into each of the second receiving grooves a2 in the form of a second droplet S2 by using the inkjet print head. Next, when the setting surface 121 is made to be a hydrophobic surface so that the cohesive force of the second solute in the second droplet S2 is greater than an outflow driving force derived from the coffee ring effect, the second droplet S2 is dried on the setting surface 121, that is, a second encapsulated quantum dot microstructure GQ including at least one green quantum dot is formed in each of the second receiving grooves a 2.

It should be noted that the first encapsulated quantum dot microstructure RQ formed in the first accommodating cavity a1 includes at least one first encapsulation (encapsulation structure) encapsulating at least one red quantum dot, and the second encapsulated quantum dot microstructure GQ formed in the second accommodating cavity a2 includes at least one second encapsulation (encapsulation structure) encapsulating at least one green quantum dot. In a possible embodiment, the first solute and the second solute may be any one of the following: lithium chloride (LiCl), sodium chloride (NaCl), potassium chloride (KCl), lithium iodide (LiI), sodium iodide (NaI), potassium iodide (KI), lithium bromide (LiBr), sodium bromide (NaBr), or potassium bromide (KBr). Incidentally, both M and NY are positive integers. In addition, a surfactant may be further added to the first quantum dot solution and the second quantum dot solution to reduce satellite droplets of the first droplet S1 and the second droplet S2 ejected from the inkjet print head.

Examples of the experiments

The inventors completed a first experiment and a second experiment. In the first experiment, a first test quantum dot solution was composed of an aqueous solvent, quantum dots having a surface hydrophilic ligand (MPA) layer, and a solute (solute), wherein the solute was sodium chloride (NaCl). In the first experiment, ethylene glycol was further added to the first test quantum dot solution as a surfactant, and the mounting surface 121 of the transparent substrate 12 was made to be a Hydrophilic surface (Hydrophilic surface) by a surface treatment process.

Fig. 6A, 6B and 6C show schematic flow charts of the first experiment. Figure 7 shows images of the evolution over time of a first test droplet into at least one salt crystal taken using bright field and dark field fluorescence microscopy. In fig. 7, the symbol "BF" is an abbreviation for the name field (bright field), and the symbol "BF" is an abbreviation for the dark field (dark field). As shown in fig. 6A and images (a) and (b) of fig. 7, after the first test droplet T1 is dropped onto a mounting surface 121 of a transparent substrate 12 by the inkjet printing head, it can be seen that the first test droplet T1 is spread outward. Further, as shown in fig. 6B, 6C, and images (C) - (f) of fig. 7, in the first test droplet T1 dropped on the mounting surface 121, the Adhesion force (Adhesion force) between the solute T12 and the quantum dot T11 promotes the quantum dot T11 to be aggregated with the NaCl crystal during evaporation of the water solvent, whereas the aggregation force (Adhesion force) between the solute T12 promotes the NaCl crystal to be shaped, and the aggregation force of the NaCl crystal repels the quantum dot T11 out of the NaCl crystal. Notably, the deposition of solute T12 is influenced by the force of the liquid-solid-gas three-phase contact line, and the Capillary force (Capillary force) gradually pushes back the solute T12 and the quantum dots T11 carried by the outer stream (outer-bound flow) to the edge of the first test droplet T1 toward the center. In this case, after the water solvent T10 is dried, a plurality of rings formed by the solute T12 and the quantum dots T11, commonly called coffee rings, appear. As shown in fig. 6C and images (e) and (f) of fig. 7, after the drying time of 30 minutes, a plurality of NaCl crystals were still formed on the mounting surface 121 of the transparent substrate 12, but the quantum dots T11 were not completely coated therein by the NaCl crystals.

In a second experiment, a second test quantum dot solution was composed of water solvent, quantum dots with a surface hydrophilic ligand (MPA) layer, and a solute (solute), wherein the solute was sodium chloride (NaCl). In addition, by further adding ethylene glycol as a surfactant to the second test quantum dot solution, satellites of the second test droplet T2 were reduced when the second test droplet T2 of the second test quantum dot solution discharged by the inkjet print head was used. It should be noted that, in the second experiment, the installation surface 121 of the transparent substrate 12 is made to be a Hydrophobic surface (hydrophic surface) by using a surface treatment process.

Fig. 8A, 8B and 8C show schematic flow charts of the second experiment. Figure 8 shows images of the evolution over time of a second test droplet into at least one salt crystal taken using bright field and dark field fluorescence microscopy. As shown in fig. 8A, 8B, 8C, and images (a) to (F) of fig. 9, in the case where the mounting surface 121 of the transparent substrate 12 is made a Hydrophobic surface (hydrophic surface), the second test droplet T2 dropped onto the mounting surface 121 by the inkjet print head maintains both the droplet shape and the contact angle (>90 °). It is assumed that the hydrophobic surface makes the cohesive force (coherence force between H2O molecules) of the solute (i.e., NaCl) of the second test droplet T2 greater than an outflow driving force derived from the coffee ring effect, so that the second test droplet T2 can maintain the droplet shape on the mounting surface 121 of the light-transmissive substrate 12.

In this case, after the aqueous solvent T20 is dried, the solute T22 and at least one quantum dot T21 form a Salt-encapsulated quantum dot microstructure (Salt-encapsulated quantum dot structure) NC on the mounting surface 121. It is understood that the salt encapsulated quantum dot microstructure NC comprises at least one sodium chloride crystal (NaCl crystal structure) coated with at least one quantum dot T21. It is worth noting that the second test droplet T2 maintained both shape and contact angle during evaporation of the aqueous solvent T20, and the droplet edge continued to move inward without pinning. In this case, in the course of the NaCl crystals gradually polymerizing and growing as the second test droplet T2 dries, the quantum dots T21 are not pushed out from the gradually polymerized NaCl crystals, but are coated in the NaCl crystals during their self-assembly, and finally the so-called salt-encapsulated quantum dot microstructure NC is produced.

Please refer to fig. 10, which shows an optical microscope image of the X × Y first encapsulated quantum dot microstructures and the X × Y second encapsulated quantum dot microstructures. As shown in fig. 10, X × Y first encapsulated quantum dot microstructures and X × Y second encapsulated quantum dot microstructures may be arranged on the arrangement surface 121 of one transparent substrate 12 by using an inkjet printing head. The size of the salt-encapsulated quantum dot microstructure NC is measured to be 3.74 + -0.5 μm, i.e. between 3.2 μm and 4.3 μm.

Second embodiment

Fig. 11 is a perspective view of a light conversion unit having inkjet printing encapsulated quantum dots and a micro light emitting diode display panel using the same according to the present invention. In a second embodiment, the micro led display panel 1 of the present invention mainly comprises: a substrate 10, mxn micro-leds 11, and a light conversion unit having inkjet printing packaged quantum dots. Fig. 12 shows an exploded perspective view of a light conversion unit with inkjet printed encapsulated quantum dots according to the present invention. In the case that the micro light emitting diode 11 is a violet micro light emitting diode, the present invention makes the light conversion unit (hereinafter referred to as "light conversion unit") having the inkjet printing encapsulation type quantum dots include: a transparent substrate 12, a light converter carrying layer 13, (M × N)/3 first encapsulated quantum dot microstructures RQ made using a first quantum dot solution, (M × N)/3 second encapsulated quantum dot microstructures GQ made using a second quantum dot solution, and (M × N)/3 third encapsulated quantum dot microstructures BQ made using a third quantum dot solution.

In more detail, the third quantum dot solution includes at least one blue quantum dot, water solvent and a third solute. Wherein the third solutes each have a concentration ranging from 0.5 wt% to 5.5 wt%, and can be any one of: lithium chloride (LiCl), sodium chloride (NaCl), potassium chloride (KCl), lithium iodide (LiI), sodium iodide (NaI), potassium iodide (KI), lithium bromide (LiBr), sodium bromide (NaBr), or potassium bromide (KBr). Then, the third quantum dot solution is respectively injected into each of the third receiving grooves A3 in the form of a third droplet S3 by using the inkjet print head, so that a third encapsulated quantum dot microstructure BQ including at least one blue quantum dot is respectively formed in each of the third receiving grooves A3 after drying. In the case of sodium chloride (NaCl) as the third solute, the third encapsulated quantum dot microstructure BQ will comprise at least one NaCl crystal coated with at least one of the green quantum dots.

Referring to fig. 13, there are shown M/3 × N/3 first encapsulated quantum dot microstructures, M/3 × N/3 second encapsulated quantum dot microstructures, and M/3 × N/3 third encapsulated quantum dot microstructures. As shown in fig. 13, M × N encapsulated quantum dot microstructures, including M/3 × N/3 first encapsulated quantum dot microstructures, M/3 × N/3 second encapsulated quantum dot microstructures, and M/3 × N/3 third encapsulated quantum dot microstructures, may be arranged on the arrangement surface 121 of one transparent substrate 12 by using an inkjet printing head. According to practical measurement, the size of each encapsulated quantum dot microstructure is 3.74 +/-0.5 μm, namely, between 3.2 μm and 4.3 μm.

Fig. 14 shows a CIE 1931 chromaticity diagram of the micro led display panel shown in fig. 12. In fig. 14, the dotted triangle represents the standard color gamut (National Television System Committee (NTSC) standard) of taiwan Television System Committee, and the solid triangle represents the color gamut (color gamut) of the micro-led display panel 1 shown in fig. 12. After comparing the two, it can be seen that the color gamut of the micro led display panel 1 proposed by the present invention is close to 110% of the color gamut of the NTSC standard.

Fig. 15 is a side cross-sectional view of a light conversion unit having inkjet printed encapsulated quantum dots of the present invention as shown in fig. 12. As shown in fig. 15, in one possible embodiment, an encapsulation material 15 may be filled in each of the first receiving grooves a1, the second receiving grooves a2, and the third receiving grooves A3 to encapsulate the first encapsulated quantum dot micro structure RQ in the first receiving groove a1, the second encapsulated quantum dot micro structure GQ in the second receiving groove a2, and the third encapsulated quantum dot micro structure BQ in the third receiving groove A3. Further, a moisture barrier layer 14 may be disposed on the optical converter carrying layer 13 and cover the plurality of first receiving grooves a1, the plurality of second receiving grooves a2, and the plurality of third receiving grooves A3.

Thus, the above description has been made in a complete and clear manner for the light conversion unit with inkjet printing encapsulation type quantum dots and the micro-led display panel using the light conversion unit according to the present invention. All embodiments and features thereof. It should be emphasized that the above-described embodiments are presently preferred, and that those skilled in the art will be able to make various changes and modifications to this invention without departing from the spirit and scope of the invention.