A characterization on hybrid lead halide perovskite solar cells with Ti02 mesoporous scaffold

Abstract

The booming perovskite solar cells (PSCs) field has emerged from the solid-state dye-sensitized photovoltaic cells with significant advances in solar to electric power conversion efficiency in a relatively short time. However, a lot a research is currently trying to explain many poorly understood aspects of its operating modes. Current density-voltage ( ) solar cells response has always been a fundamental photovoltaics characterization, and specifically on PSCs it presents an anomalous hysteretic behavior whose origin has been mainly addressed to ferroelectric or ionic effects. Here we show, on the basis of a CH3NH3PbI3-xClx with a mesoporous TiO2 scaffold based solar cells characterization, that such anomalous hysteresis can be better explained in terms of interface capacitive ionic slow dynamic processes. Furthermore, we present a methodological review for the proper performance of Mott-Schottky analysis in PSCs stressing on the importance of complementary impedance spectroscopy characterization. On this issue we highlight our finds of an analogous hysteresis and an exponential capacitance excess on capacitance-voltage characteristics that can be associated with an exponential density of localized states below the conduction band. Our calculus of the corresponding total density of localized states supports our stands for interface processes.