OLED DEVICE HAVING IMPROVED LIGHT OUTPUT

1 . An organic light-emitting diode (OLED) device, comprising:

a transparent substrate;

one-or-more transparent thin-film transistors located over the substrate;

one or more light-emitting elements formed over the transparent thin-film transistors, wherein each light-emitting element comprises:

a first transparent extensive electrode formed at least partially over at least a portion of the one-or-more transparent thin-film transistors;

at least one layer of light-emitting organic material formed over the first transparent extensive electrode; and

a second reflective electrode formed over the at least one layer of light-emitting organic material;

a low-index layer formed between the first transparent extensive electrode and the one-or-more thin-film transistors, the low-index layer having a lower optical index than that of the layer of light-emitting organic material, the transparent thin-film transistors, and the transparent substrate; and

a light-scattering layer formed between the low-index layer and the second reflective electrode, or formed as part of the second reflective electrode.

2 . The OLED device of claim 1 , wherein the scattering layer is formed between the low-index layer and the first transparent extensive electrode.

3 . The OLED device of claim 1 , wherein the second reflective electrode is a multi-layer electrode including a transparent layer and a reflective layer, the transparent layer being between the reflective layer and the one-or-more layer of organic material.

4 . The OLED device of claim 3 , wherein the scattering layer is formed between at least a portion of the transparent layer and a portion of the reflective layer.

5 . The OLED device of claim 1 , wherein the thin-film transistors are inorganic.

6 . The OLED device of claim 1 , wherein the thin-film transistors comprise metal oxide.

7 . The OLED device of claim 6 , wherein the metal oxide comprises zinc oxide, doped zinc oxide, or aluminum zinc oxide.

8 . The OLED device of claim 1 , wherein the thin-film transistors are organic.

9 . The OLED device of claim 1 , wherein the substrate is flexible.

10 . The OLED device of claim 1 , wherein the substrate comprises a polymer.

11 . The OLED device of claim 1 , wherein the transparent thin-film transistors are formed from zinc-oxide-based nano-particles.

12 . The OLED device of claim 1 , wherein the transparent thin-film transistors are formed by a method comprising the steps of:

(a) applying a seed coating comprising a colloidal solution of zinc-oxide-based nanoparticles having an average primary particle size of 5 to 200 nm to the transparent substrate;

(b) drying the seed coating to form a porous layer of zinc-oxide-based nanoparticles;

(c) applying, over the porous layer of nanoparticles, an overcoat solution comprising a soluble zinc-oxide-precursor compound that converts to zinc oxide upon annealing, to form an intermediate composite film;

(d) drying the intermediate composite film; and

(e) annealing the dried intermediate composite film at a temperature of at least 50° C. to produce a semiconductor film comprising zinc-oxide-based nanoparticles supplemented by additional zinc oxide material formed by the conversion of the zinc-oxide-precursor compound during the annealing of the composite film.

13 . The OLED device of claim 12 , further comprising annealing the porous layer of zinc-oxide-based nanoparticles at a temperature higher than the temperature of step (a) or (b) prior to applying the overcoat solution in step (c).

14 . An OLED device of claim 12 , wherein seed solution of step (a) and overcoat solution of step (c) are applied by ink-jet printing.

15 . The OLED device of claim 1 , wherein the transparent thin-film transistors are formed by simultaneously directing a series of gas flows along elongated channels such that the gas flows are substantially parallel to a surface of the substrate and substantially parallel to each other, whereby the gas flows are substantially prevented from flowing in the direction of the adjacent elongated channels, and wherein the series of gas flows comprises, in order, at least a first reactive gaseous material, inert purge gas, and a second reactive gaseous material, wherein the first reactive gaseous material is capable of reacting with a substrate surface treated with the second reactive gaseous material.

16 . A method of making an organic light-emitting diode (OLED) device, comprising:

providing a transparent substrate;

forming one-or-more transparent thin-film transistors located over the substrate;

forming one or more light-emitting elements formed over the transparent thin-film transistors, wherein each light-emitting element comprises:

a first transparent extensive electrode formed at least partially over at least a portion of the one-or-more transparent thin-film transistors;

at least one layer of light-emitting organic material formed over the first transparent extensive electrode; and

a second reflective electrode formed over the at least one layer of light-emitting organic material;

forming a low-index layer between the first transparent extensive electrode and the one-or-more thin-film transistors, the low-index layer having a lower optical index than that of the layer of light-emitting organic material; and

forming a light-scattering layer between the low-index layer and the second reflective electrode, or formed as part of the second reflective electrode.