On the modeling and simulation of of reaction-transfer dynamics in semiconductor-electrolyte solar cells

The mathematical modeling and numerical simulation of semiconductor-electrolyte systems play important roles in the design of high-performance semiconductor-liquid junction solar cells. We propose in this work a macroscopic mathematical model, a system of nonlinear partial differential equations, for the complete description of charges transfer dynamics in such systems. The model consists of a reaction-drift-diffusionPoisson system that models the transport of electron-hole pairs in the semiconductor region and an equivalent system that describes the transport of reductant-oxidant pairs in the electrolyte region. The coupling between the semiconductor and the electrolyte is modeled through a set of interfacial reactive and current balance conditions. We present some numerical simulations to illustrate the quantitative behavior of the semiconductor-electrolyte system in both dark and illuminated environments. We show numerically that one can replace the electrolyte region in the system with a Schottky contact only when the bulk reductant-oxidant pair density is extremely high. Otherwise, such replacement gives significantly inaccurate description of the real dynamics of the semiconductor-electrolyte system.