Temperature Characterization of Perovskite LEDs by Electroluminescence

Abstract

Despite the rapid progress in perovskite lightemitting diodes (PeLEDs), achieving high stability remains an outstanding challenge. PeLEDs produce heat during operation, raising the temperatures, which accelerate device degradation. To determine the PeLED temperatures, a very limited number of techniques represented by infrared thermal imaging (ITI) are employed. However, ITI mainly characterizes the temperature of the exposed top surface of the device, leaving the actual temperature in the perovskite emissive layer unresolved. Here, we address this challenge by directly characterizing the temperature of the perovskite layer via an electroluminescence (EL) analysis. Model PeLEDs emitting in the near-infrared (FAPbI 3 ), red (FA 0.5 Cs 0.5 PbI 2 Br) and green (FA 0.6 Cs 0.7 PbBr 3 ) spectral regions are tested. Urbach energies related to thermal broadening are obtained from the EL spectra, enabling real-time tracking of the perovskite emissive layer temperature under working conditions. Our results demonstrate that the EL analysis is a simple and effective method for the operando temperature characterization of PeLEDs.