LAUSR

Perovskite light emitting diode has almost reached the threshold for potential commercialization within a few years of research. However, there are still some unsolved puzzles such as large ideality factor and presence of large negative capacitance especially at low frequency regime yet to be addressed. Here we have fabricated methylammonium lead tri-bromide perovskite n-i-p structure for light emitting diode from a smooth and textured emissive layer and demonstrated for the first time that these two factors are strongly dependent on the perovskite film morphology. Bias dependent capacitance measurement also reveals the transition between negative to positive capacitance in textured film at low frequency regime. We have observed an anomalous capacitive behavior at mid-frequency regime in smooth perovskite film but disappearing in textured film. Relatively large ideality factor and anomalous capacitive behavior observed in perovskite light emitting diode is due to the presence of strong coupling between ions and electrons near the electrode interface. Therefore, ideality factor as well as anomalous capacitance at mid-frequency regime can be decreased by minimizing electronic-ionic coupling in textured perovskite film while light out-coupling can be improved significantly.