Low turn-on voltage perovskite light-emitting diodes with methanol treated PEDOT:PSS as hole transport layer

We demonstrate the reduced low turn-on voltage of perovskite light-emitting diodes (PeLEDs) with methanol (MeOH) treated poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) as a hole transport layer (HTL). The MeOH treated PEDOT:PSS layer presents improved hole injection through reducing the contact barrier between the HTL and the CH3NH3PbBr3 emitting layer without sacrificing the quality of the perovskite film, which was characterized by X-ray diffraction, scanning electron microscopy, and time-resolved photoluminescence analysis. The optimized PeLEDs with the MeOH treated PEDOT:PSS layer exhibit a low turn-on voltage of 2.4 V and a maximum luminance of 1565 cd/m2, which represents a significant improvement over the PeLEDs using a pristine PEDOT:PSS layer. The approach could be used as a general method for decreasing the hole-injection barrier of PeLEDs and, eventually, to enhance the device performance.