Lifetime study of white organic light emitting diodes fabricated by both solution and vacuum evaporation processes

Abstract

In this study, a white light organic light-emitting diode is fabricated by solution processes. The focus of the research is to extend the lifetime of device. A hole transport layer doped with P-type material (F4-TCNQ) and a stepped electron transport layer TPBi (blocking holes and lowering the LUMO energy level) were employed in the device structure. And each layer thickness was optimized. At 9 V, the brightness can reach 206 cd/m2, current efficiency 1.29 cd/A, and the device lifetime is extended from 0.8 to 8 hours. The CIE color-coordinates of white OLED samples are (0.38, 0.28).