Correlation of ETL in perovskite light-emitting diodes and the ultra-long rise time in time-resolved electroluminescence

Abstract Here, two series CH 3 NH 3 PbI 3 based perovskite light-emitting diodes (Pe-LEDs) were synthesized with TiO 2 and SnO 2 as electron transport layer (ETL), respectively. An exceptional ultra-long rise time ( T r ) persisting to tens of seconds was observed in time-resolved electroluminescence (EL) characteristics from the Pe-LEDs as driven with constant voltage, which might be intrinsic to the MAPbI 3 perovskite layer regardless of the ETL materials. Qualitatively, SnO 2 based ETL was preferred than the TiO 2 ETL counterpart for faster response Pe-LED devices with lower T r . Moreover, the T r of Pe-LED can be adjusted in the range of 10–28 s by precisely controlling the thickness of SnO 2 ETL. In addition, the similar trend was also confirmed in the SnO 2 ETL thickness dependent hysteresis index deduced from current-voltage ( J-V ) characteristics. The mechanism was interpreted by means of dynamics of carrier injection and transport at the perovskite/ETL interface. These achievement may contribute to better understanding of the origin and mechanism of the slow process in EL characteristics, and hence favorable for minimizing this detrimental effects.