Efficient all-inorganic perovskite light-emitting diodes with a multifunctional potassium bromide doped hole transport layer

Perovskite light-emitting diodes (PeLEDs) are regarded as exceptional candidates for next-generation high-definition displays. Despite the fact that the all-inorganic perovskites possess an advantage in structural stability among the perovskite family, the electroluminescence (EL) performance of their corresponding PeLEDs are still challenged by the difficulties in depositing smooth, uniform perovskite films and realizing chare balance under working voltages. Here, we report an efficient and stable CsPbBr 3 based PeLED, which is enabled by a hole transport layer (HTL) of KBr doped poly(3,4,-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). The KBr dopant can not only improve the charge balance by boosting the hole injection, but also suppress the exciton quenching through passivating halide defects in perovskites. The resulting PeLED exhibits a maximum current efficiency (CE) of 35.09 cd A −1 and a maximum external quantum efficiency (EQE) of 10.02%, which are over 12-fold higher than those of the control device based on undoped HTL, respectively. Our work provides an easy and efficient strategy to boost the EL performance of all-inorganic perovskites.