Temperature\nCharacterization of Perovskite LEDs by\nElectroluminescence

Despite the rapid progress in perovskite\nlight-emitting\ndiodes\n(PeLEDs), achieving high stability remains an outstanding challenge.\nPeLEDs produce heat during operation, raising the temperatures, which\naccelerate device degradation. To determine the PeLED temperatures,\na very limited number of techniques represented by infrared thermal\nimaging (ITI) are employed. However, ITI mainly characterizes the\ntemperature of the exposed top surface of the device, leaving the\nactual temperature in the perovskite emissive layer unresolved. Here,\nwe address this challenge by directly characterizing the temperature\nof the perovskite layer via an electroluminescence (EL) analysis.\nModel PeLEDs emitting in the near-infrared (FAPbI<sub>3</sub>), red\n(FA<sub>0.5</sub>Cs<sub>0.5</sub>PbI<sub>2</sub>Br) and green (FA<sub>0.6</sub>Cs<sub>0.7</sub>PbBr<sub>3</sub>) spectral regions are tested.\nUrbach energies related to thermal broadening are obtained from the\nEL spectra, enabling real-time tracking of the perovskite emissive\nlayer temperature under working conditions. Our results demonstrate\nthat the EL analysis is a simple and effective method for the operando\ntemperature characterization of PeLEDs.