Thermal transfer film, and organic electroluminescent device prepared using same

1. A thermal transfer film comprising:

a base layer; and

a light-to-heat conversion layer formed on the base layer, the light-to-heat conversion layer comprising a cured product of a composition for a light-to-heat conversion layer, the composition comprising a UV curable resin, a polyfunctional monomer, a light-to-heat conversion material and an initiator,

wherein the light-to-heat conversion layer includes a first layer stacked on the base layer and a second layer stacked on the first layer in a thickness direction,

the light-to-heat conversion material is more distributed in the first layer than in the second layer, and wherein the second layer has a surface roughness (Ra) of about 10 nm or less on its upper surface.

2. The thermal transfer film according to claim 1 , wherein a ratio (C1/C2) of concentration (C1) of the light-to-heat conversion material in the first layer to concentration (C2) of the light-to-heat conversion material in the second layer is about 1.5 or more.

3. The thermal transfer film according to claim 1 , wherein the first layer has a thickness of about 20% to about 90% of a total thickness of the light-to-heat conversion layer.

4. The thermal transfer film according to claim 1 , wherein the first layer has a thickness of about 0.1 μm to about 10 μm, and the second layer has a thickness of about 0.05 μm to about 10 μm.

5. The thermal transfer film according to claim 1 , wherein the light-to-heat conversion material is dispersed throughout the first layer.

6. The thermal transfer film according to claim 1 , wherein the first layer comprises a first region and a second region in the thickness direction, and the light-to-heat conversion material is more distributed in the first region than in the second region.

7. The thermal transfer film according to claim 6 , wherein a ratio (t12/t11) of thickness (t12) of the second region to thickness (t11) of the first region is about 5 or less.

8. The thermal transfer film according to claim 1 , wherein the light-to-heat conversion material has a gradually increasing concentration with increasing distance from an interface between the first layer and second layer to a lower surface of the first layer.

9. The thermal transfer film according to claim 1 , wherein the light-to-heat conversion material comprises at least one of a dye and a pigment.

10. The thermal transfer film according to claim 1 , wherein the light-to-heat conversion material has a particle shape.

11. A thermal transfer film comprising:

a base layer; and

a light-to-heat conversion layer formed on the base layer, the light-to-heat conversion layer comprising a cured product of a composition for a light-to-heat conversion layer, the composition comprising a UV curable resin, a polyfunctional monomer, a light-to-heat conversion material and an initiator,

wherein the light-to-heat conversion layer is a single layer having a first region adjacent the base layer in a thickness direction and a second region adjacent the first region in a thickness direction, and

the light-to-heat conversion material is more distributed in the first region than in the second region, and wherein the second region has a surface roughness (Ra) of about 10 nm or less on its upper surface.

12. The thermal transfer film according to claim 1 , wherein the composition comprises about 10 wt % to about 80 wt % of the UV curable resin, about 5 wt % to about 50 wt % of the polyfunctional monomer, about 5 wt % to about 50 wt % of the light-to-heat conversion material and about 0.1 wt % to about 10 wt % of the photo initiator in terms of solid content.

13. The thermal transfer film according to claim 1 , wherein the composition further comprises at least one of a curable fluorine compound and a curable siloxane compound.

14. The thermal transfer film according to claim 13 , wherein the curable fluorine compound is represented by Formula 1:

(CH 2 ═CR 1 COO) n R f ,  <Formula 1>

(wherein n is an integer of 2 or more;

R 1 is hydrogen, or a C 1 to C 5 linear or branched alkyl group; and

R f is represented by any one of Formulae a to e:

(wherein * is a bonding site;

R F1 is a C 1 to C 10 linear or branched perfluoroalkylene group; and

R F2 , R F3 , R F4 and R F5 are each hydrogen, or a C 1 to C 14 linear or branched perfluoroalkyl group)).

15. The thermal transfer film according to claim 13 , wherein the curable siloxane compound comprises polyether-modified dialkyl polysiloxane containing a (meth)acrylic group.

16. The thermal transfer film according to claim 13 , wherein the composition comprises about 10 wt % to about 80 wt % of the UV curable resin, about 5 wt % to about 50 wt % of the polyfunctional monomer, about 5 wt % to about 50 wt % of the light-to-heat conversion material, about 0.1 wt % to about 10 wt % of the photo initiator and about 0.01 wt % to about 10 wt % of the at least one of the curable fluorine compound and the curable siloxane compound in terms of solid content.

17. The thermal transfer film according to claim 1 , wherein the base layer comprises a film formed of at least one of polyester resins, polyacrylic resins, polyepoxy resins, polyolefin resins, and polystyrene resins.

18. The thermal transfer film according to claim 1 , wherein the light-to-heat conversion layer comprises a transfer layer stacked thereon.

19. The thermal transfer film according to claim 1 , wherein the light-to-heat conversion material comprises at least one of carbon black and tungsten oxide.

20. An organic electroluminescent device prepared using the thermal transfer film according to claim 1 as a donor film.