Current-voltage characteristics of perovskite solar cells incorporating bulk and surface recombination: comparison of a physics-based model calculations with experiments

This paper explains the effects of bulk and interface recombination on the current-voltage characteristics of bulk heterojunction perovskite solar cells. A physics-based comprehensive analytical model for studying the carrier distribution and photocurrent alongside with the current-voltage characteristics has been proposed. The model considers exponential photon absorption profile, bulk and surface recombination, and carrier drift and diffusion in the photon absorption layer. By solving the continuity equation for both electrons and holes in the perovskite layer, analytical formulae for the position-dependent carrier concentration and associated voltage-dependent photocurrent have been constructed. The position-dependent total conduction current (sum of the drift and diffusion currents of both holes and electrons) under steady state is found to be space invariant which is exactly equal to the total photocurrent calculated using the Shockley-Ramo's theorem. The calculation of the total load current considers the actual solar spectrum, photocurrent and voltage-dependent forward dark current. The mathematical model is fitted with published experimental results of various perovskite solar cells, and the charge carrier parameters are extracted. The charge carrier transport parameters, especially the carrier mobility and surface recombination, have very significant effects on the current-voltage characteristics and power conversion efficiency.