Electrical Modeling of Perovskite Solar Cells

Abstract

High-performance perovskite solar cells (PSCs) have attracted great attention from researchers around the world. Rapid researches and developments of PSCs are shown by the increase of its efficiency from 3.8% in 2009 to a new world record of 22.4% in 2017. Hysteresis phenomenon in current density voltage (J-V) is one of the challenges occurring in some specific PSCs that should be overcome to continue the improvement of PSCs. This phenomenon occurs when a voltage is swept with different scan directions from negative to positive value (forward) and positive to negative value (backward). Hysteresis effect results in a different maximum power point on the J-V characteristic leading to under- or overestimation of PSCs efficiency.

Furthermore, when the applied voltage is abruptly changed, a transient current density response is introduced implying a capacitive behaviour. Due to this behaviour, there is an indication that PSCs cannot be represented by the conventional equivalent circuit. Thus, the purpose of this project is to investigate hysteresis phenomenon in PSC by electrical modelling. In this project, a PSC sample was fabricated by Solliance Solar Research. Time-resolved J-V measurement was done to obtain more insight of J(t) as a function of applied voltage. The hysteresis phenomenon was analyzed in different voltage scan direction and various scan rates. Simulation of band diagram in dark condition was done to understand working principle of PSC device. Two predicted equivalent circuit of the cell were derived from the simulated band diagram. These equivalent circuit models considered the charge accumulation at the bulk of perovskite and at the interface between charge transport layers and perovskite. Furthermore, two additional equivalent circuit models were proposed to represent the hysteresis effect. J(t) curve fitting of measurement results and simulation was employed to verify the equivalent circuit. This insight might help to get a better understanding of hysteresis effect in PSCs.