Mechanisms of charge accumulation in the dark operation of perovskite solar cells

Abstract

In this work, a new current peak at forward bias in the dark current–voltage curves has been identified for standard mesoscopic perovskite solar cells. This characteristic peak appears only under some specific conditions, mainly in the reverse scan (RS) direction and when the solar cells were kept for several seconds under short-circuit conditions before starting the RS measurement. This peak disappears when the above experimental conditions are not applied. It is considered that this uncommon diode shape is obtained because shallow and/or deep trap states located at the interface between either perovskite/ p-type or perovskite/n-type transport materials are dynamically filled during the RS voltage scan. To corroborate this hypothesis, the response of hole tran sport materials (HTMs), small molecule spiro-OMeTAD and polymer P3HT, as well as both HTMs with additives, was compared. Also perovskite absorbers such as CH 3 NH 3 PbI 3 and all-inorganic perovskite based on cesium (CsPbI 3 ) were also analyzed, achieving in all cases similar trends.