Capacitance–voltage characteristics of perovskite light-emitting diodes: Modeling and implementing on the analysis of carrier behaviors

Analyzing and optimizing carrier behaviors are essential to achieve high electroluminescence performance in perovskite light-emitting diodes (PeLEDs). In this work, a capacitance–voltage (C–V) model for PeLEDs is established to describe carrier behaviors. Four distinct regions in this typical C–V model, including a neutrality region, a barrier region, a carrier diffusion region, and a carrier recombination region, were analyzed. Importantly, the C–V model is implemented to guide the electroluminescence (EL) performance improvement in PeLEDs. By studying the measured C–V characteristics of a typical PeLED, issues of a high hole injection barrier and insufficient recombination are revealed. To address them, one MoO3 interface layer with deep conduction band minimum is designed between a hole transport layer and a hole injection layer to enhance the hole injection. The C–V characteristics for the optimized PeLED confirm the reduced injection barrier and strengthened recombination rate. The optimized PeLED shows an improved external quantum efficiency from 8.34% to 15.82%. The C–V model helps us to quantitatively understand the essential carrier behaviors in PeLEDs and can serve as an efficient method to improve the EL performance of PeLEDs.