Highly efficient orange and white OLEDs based on ultrathin phosphorescent emitters with double reverse intersystem crossing system

Abstract

Actualizing highly efficient organic light-emitting diodes (OLEDs) based on multiple doping technique is still a complicated manufacturing process and difficult to control precisely. In this paper, we reported high-efficiency and simplified orange and white OLEDs by combining ultrathin emitting layer with double reverse intersystem crossing (RISC) system. By doping thermally activated delayed fluorescence material into acceptor of interfacial exciplex as a sensitizer, the resulting orange OLEDs showed a maximum external quantum efficiency of 20.4%, which remained 18.7% at a luminance of 1000 cd/m2. In addition, the exciton quenching mechanism was explored by theoretical method, and the significance of novel design was understood by investigating excitons density experimentally. Furthermore, white OLED was achieved by restraining energy transfer between bluish-green emission layer and orange ultrathin layer, reaching maximum current efficiency and power efficiency of 52.4 cd/A and 60.9 lm/W with the Commission Internationale de L'Eclairage (CIE) coordinates variation of (0.002, 0.016) over a wide luminance range, which is one of the best performance in hybrid white OLED based on ultrathin-layer architecture.