Method of aligning micro LEDs and method of manufacturing micro LED display using the same

1. A method of aligning light-emitting diodes (LEDs), the method comprising:

providing micro LEDs, each of the micro LEDs having a first surface that has a first maximum width D 1 and a second surface that is opposite to the first surface and has a second maximum width D 2 that is greater than the first maximum width D 1 ;

providing a transfer substrate including a transfer mold that has an array of openings, each of the openings being configured to accommodate the first surface of a corresponding micro LED and not accommodate the second surface of the corresponding micro LED; and

aligning the micro LEDs in one direction in the openings of the transfer mold by inserting the micro LEDs into the openings of the transfer mold so that the first surface of each of the micro LEDs is positioned within a corresponding opening,

wherein a third maximum width of each of the openings is less than the second maximum width D 2 of the second surface of each of the micro LEDs and greater than the first maximum width D 1 of the first surface of each of the micro LEDs.

2. The method of claim 1 , wherein the aligning of the micro LEDs in the one direction in the openings of the transfer mold is repeated until none of the openings are empty or until none of the micro LEDS are misaligned with respect to the openings.

3. The method of claim 2 , wherein the aligning of the micro LEDs in the one direction in the openings of the transfer mold comprises removing at least one micro LED that is misaligned.

4. The method of claim 1 , wherein a depth of each of the openings is less than a thickness of each of the micro LEDs.

5. The method of claim 1 , wherein a shape of a cross-section of each of the openings corresponds to a shape of a cross-section of each of the micro LEDs.

6. The method of claim 1 , wherein each of the micro LEDs has a slanted side surface connecting the first surface and the second surface.

7. The method of claim 6 , wherein each of the micro LEDs has a core-shell structure.

8. The method of claim 7 , wherein the slanted side surface of each of the micro LEDs has an inclination angle of about 58 degrees or about 62 degrees.

9. The method of claim 1 , wherein a maximum width of each of the micro LEDs taken along an intermediate thickness cross-section thereof is Dc,

a maximum width of each of the openings is Dt, and

the micro LEDs and the openings satisfy: D 1 <Dc<Dt<D 2 and 0<Dt−Dc<D 2 −Dc.

10. The method of claim 9 , wherein each of the openings is further configured to accommodate the corresponding micro LED to a depth equivalent to at least half a thickness of the corresponding micro LED.

11. The method of claim 9 , wherein a thickness of each of the micro LEDs from the first surface to the second surface is HLED, and a value (D 2 −Dc)/HLED is about 0.312435 or about 0.265855.

12. The method of claim 1 , wherein the micro LEDs are micro LED flakes, and

wherein the aligning of the micro LEDs comprises placing the micro LED flakes on the transfer substrate so that the first surface of each of the micro LED flakes is inserted into the corresponding opening of the transfer mold.

13. A method of manufacturing a light-emitting diode (LED) display, the method comprising:

forming a display including unit pixels by aligning micro LEDs in one direction on a transfer substrate, the aligning the micro LEDs comprising:

providing the micro LEDs, each of the micro LEDs having a first surface that has a first maximum width D 1 and a second surface that is opposite to the first surface and has a second maximum width D 2 that is greater than the first maximum width D 1 ;

providing the transfer substrate including a transfer mold that has an array of openings, each of the openings being configured to accommodate the first surface of a corresponding micro LED and not accommodate the second surface of the corresponding micro LED; and

aligning the micro LEDs in the one direction in the openings of the transfer mold by inserting the micro LEDs into the openings of the transfer mold so that the first surface of each of the micro LEDs is positioned within a corresponding opening,

wherein a third maximum width of each of the openings is less than the second maximum width D 2 of the second surface of each of the micro LEDs and greater than the first maximum width D 1 of the first surface of each of the micro LEDs.

14. The method of claim 13 , further comprising forming, on the openings of the transfer mold in which the micro LEDs are aligned, a color conversion layer for converting a wavelength of light emitted by the micro LEDs,

wherein the transfer substrate is a display substrate.

15. The method of claim 14 , wherein the color conversion layer is formed so that each of the unit pixels includes a plurality of pixels of different colors.

16. A method of manufacturing a light-emitting diode (LED) display, the method comprising:

providing micro LEDs, each of the micro LEDs having a first surface that has a first maximum width D 1 and a second surface that is opposite to the first surface and has a second maximum width D 2 that is greater than the first maximum width D 1 ;

providing a transfer substrate including a transfer mold that has an array of openings, each of the openings being configured to accommodate the first surface of a corresponding micro LED and not accommodate the second surface of the corresponding micro LED;

aligning the micro LEDs in one direction in the openings of the transfer mold by inserting the micro LEDs into the openings of the transfer mold so that the first surface of each of the micro LEDs is positioned within a corresponding opening; and

forming a plurality of unit pixels by transferring the micro LEDs aligned in the one direction on the transfer substrate to a display substrate through bonding,

wherein a third maximum width of each of the openings is less than the second maximum width D 2 of the second surface of each of the micro LEDs and greater than the first maximum width D 1 of the first surface of each of the micro LEDs.

17. The method of claim 16 , further comprising forming, on the display substrate to which the micro LEDs are transferred, a color conversion layer for converting a wavelength of light emitted by the micro LEDs.

18. The method of claim 17 , wherein the color conversion layer is formed so that each of the unit pixels includes a plurality of pixels of different colors.

19. A micro light-emitting diode (LED) display comprising:

micro LEDs, each of the micro LEDs having a first surface that has a first maximum width D 1 and a second surface that is opposite to the first surface and has a second maximum width D 2 ; and

a transfer substrate including a transfer mold that has an array of openings, each of the openings being configured to accommodate the first surface of a corresponding micro LED and not accommodate the second surface of the corresponding micro LED, and the micro LEDS being inserted and aligned in one direction in the openings of the transfer mold so that the first surface of each of the micro LEDs is positioned within a corresponding opening,

wherein a third maximum width of each of the micro LEDs along an intermediate thickness cross section thereof is Dc, and a fourth maximum width of each of the openings is Dt,

wherein the micro LEDs and the openings satisfy: D 1 <Dc<Dt<D 2 and 0<Dt−Dc<D 2 −Dc, and

wherein the transfer substrate is a display substrate configured to form a plurality of unit pixels.

20. The method of claim 1 , wherein an intermediate thickness cross-section through a midpoint between the first surface and the second surface is smaller than a maximum width of each of the openings.