Effective intrinsic charge carrier correction for interface charge transfer modeling of perovskite solar cells in dark conditions

Abstract

Modeling the transport at the interfaces between the charge-transport-layer (CTL) and the perovskite is essential to describe the performance of perovskite solar cells (PSCs), whose electrical response is driven by dual ionic and electronic transport. This ionic-electronic transport promotes peculiar capacitive behaviors, such as the case of dark current–voltage hysteresis experiments with a strong dependence on the CTL. In this work, we develop a simulation model based on the drift–diffusion differential equations with a specific treatment of the interfaces. We model the perovskite/CTL (pvk/CTL) interface as a buffer region in which band-to-band or Shockley–Read–Hall (SRH) recombination take place. This buffer region has its own effective bandgap energy and layer thickness. Moreover, current leakages are incorporated in the simulation in order to achieve a similar order of magnitude to that measured in experimental current densities. Our model is tested with dark current–voltage experiments, and a similar trend is observed between the medium/high frequency hysteresis in the experimental and simulated current–voltage curves. We highlight the importance of considering material modifications in interface recombination models to interpret experimental hysteresis and to quantify the role of selective contacts in the electrical response of PSCs.