Improving Extraction Efficiency Of OLED Based On Holographic Lithography Microstructure

This thesis focuses on the research of micro-structure patterns to improve the light extraction efficiency(LEE)of organic light-emitting diodes(OLEDs).The experimental results show that by introducing the one-dimensional grating,the two-dimensional grating,and the disordered nano-patterns in the ITO layer of the OLED,the LEE of the OLED is significantly improved.The FDTD software was used to study the effect of grating period and etching depth on the transmittance and electric field of OLED.The technologies of holographic lithography and wet etching are used to fabricate the grating on the ITO substrate for the orange OLED,and the influence of the grating on the device performance are studied.The device results show that when the one-dimensional grating period is 350 nm and the etching depth is 20 nm,the maximum external quantum efficiency is increased by 29.5%.When the two-dimensional dot array period is 350 nm and the etching depth is 40 nm,the external quantum efficiency is improved by 49.5%.When the period of the two-dimensional hole array is 350 nm and the etching depth is 40 nm,the external quantum efficiency is increased by 61.5%.The experimental results show that grating patterns can significantly improve the light output efficiency of OLED devices.The technologies of gold thin-film annealing and wet etching are adopted to prepare disordered nano patterns on the ITO substrate for the orange OLED,and the influence of disordered nano patterns on the devices performance are studied.The results show that when the thickness of gold film is 10 nm,the annealing temperature is 570 °C,the annealing time is 240 s,and the etching depth is 30 nm,the external quantum efficiency is increased by 35%.The experimental results show that disordered nano patterns can effectively improve the LEE of OLED.