Inkjet printed organic light-emitting diodes employing organometal-halide perovskite as hole transport layer

Abstract

Due to their narrow spectrum and high photoluminescence quantum yield, organic-inorganic hybrid perovskite materials have become an important emitter for light-emitting diodes (LED). In addition to the perovskite emitters, other perovskite materials such as methyl lead ammonium chloride (MAPbCl3) with high charge mobility can potentially be used as excellent charge transport materials. In this work, phosphorescence LED devices in which MAPbCl3 was employed as hole transport layer (HTL) was designed and fabricated by inkjet printing (IJP) process. Ethanolamine was added to the poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonate) hole injection layer (HIL) to control the crystallization process and to suppress the surface defects of MAPbCl3. In addition, polyethylene oxide was doped into MAPbCl3 to improve the printability and the quality of film formation. The ‘blurred interface’ concept was successively applied to enable for the first time the IJP of three layers (HIL, HTL and emitter layers) in the LEDs. The fabricated multilayer LEDs achieved the maximum external quantum efficiency of 8.9%, maximum current efficiency of 30.8 cd A−1, and maximum power efficiency of 10.7 lm W−1. A 40 × 40 mm2 OLED light emitting device was successfully fabricated by IJP technology.