Method for manufacturing a display device

1. A method for manufacturing a display device, comprising the steps of:

forming a bottom electrode for supplying a first charge, in individual pixels on a substrate;

forming a hole injection layer over the bottom electrode;

forming a hole transport layer over the hole injection layer;

forming a pattern of a first light-emitting layer having a first-charge transport property above the bottom electrode in part of the pixels;

subjecting the substrate having the first light-emitting layer formed thereon to heat treatment, so as to planarize exposed surfaces of the first light-emitting layer and of the hole transport layer, the top surface of the first light-emitting layer serving as an emission region;

forming a pattern of a second light-emitting layer having a second-charge transport property on the heat-treated surface above the bottom electrode in another part of the pixels, a lower surface of the second light-emitting layer, which serves as an emission region, is planarized due to being formed on the planarized exposed surface of the hole transport layer; and

forming a top electrode for supplying a second charge so that the first light-emitting layer and the second light-emitting layer are sandwiched between the bottom electrode and the top electrode.

2. The method according to claim 1 , wherein each of the formation of the pattern of the first light-emitting layer and the formation of the pattern of the second light-emitting layer is conducted by a transfer method.

3. The method according to claim 1 , wherein the heat treatment is conducted at a temperature which is lower than a melting temperature of an organic material constituting the first light-emitting layer, and which is near a glass transition temperature of the organic material.

4. The method according to claim 1 , further comprising the step of, after forming the bottom electrode and before forming the pattern of the first light-emitting layer, forming a first-charge transport layer on the bottom electrode,

wherein

the heat treatment is conducted at a temperature lower than the melting temperature of an organic material constituting the first-charge transport layer.

5. The method according to claim 1 , further comprising the step of, after forming the second light-emitting layer and before forming the top electrode, forming a second-charge transport layer on the first light-emitting layer and the second light-emitting layer.

6. The method according to claim 1 , wherein:

the first charge is a positive charge and the bottom electrode is formed as an anode, and

the second charge is a negative charge and the top electrode is formed as a cathode.