Pixel structure of electroluminescent display panel

A pixel structure of an electroluminescent display panel, having a first sub-pixel region, a second sub-pixel region and a third sub-pixel region, the first sub-pixel region, the second sub-pixel region and the third sub-pixel region being used for providing a first primary color light, a second primary color light and a third primary color light respectively, the pixel structure of the electroluminescent display panel comprising:

• a first anode, disposed in the first sub-pixel region;
• a second anode, disposed in the second sub-pixel region;
• a third anode, disposed in the third sub-pixel region;
• a first organic light-emitting layer, disposed at least in the first sub-pixel region, the second sub-pixel region and the third sub-pixel region, wherein the first organic light-emitting layer comprises a first organic light-emitting material;
• a second organic light-emitting layer, disposed at least in the second sub-pixel region and the third sub-pixel region, wherein the first organic light-emitting layer overlaps the second organic light-emitting layer in the second sub-pixel region, and the second organic light-emitting layer comprise a second organic light-emitting material and a third organic light-emitting material;
• a first cathode, disposed in the first sub-pixel region;
• a second cathode, disposed in the second sub-pixel region;
• a third cathode, disposed in the third sub-pixel region;
• at least one first hole transport layer, disposed in the first sub-pixel region;
• at least one second hole transport layer, disposed in the second sub-pixel region;
• and
• at least one third hole transport layer, disposed in the third sub-pixel region, wherein the at least one third hole transport layer comprises a single-layered hole transport layer, and the single-layered hole transport layer comprises a mixture of a hole transmission material with a low carrier mobility and a hole transmission material with a high carrier mobility;
• wherein a first micro cavity is formed between the first anode and the first cathode in the first sub-pixel region, a second micro cavity is formed between the second anode and the second cathode in the second sub-pixel region, a third micro cavity is formed between the third anode and the third cathode in the third sub-pixel region, and the at least one first hole transport layer, the at least one second hole transport layer and the at least one third hole transport layer have different thicknesses to render the first micro cavity, the second micro cavity and the third micro cavity having different cavity lengths, and
• wherein a wavelength of the third primary color light is greater than a wavelength of the second primary color light, the wavelength of the second primary color light is greater than a wavelength of the first primary color light, and a carrier mobility of the third hole transport layer is different from a carrier mobility of the second hole transport layer.