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

TL;DR

This paper develops a comprehensive macroscopic model using nonlinear PDEs to simulate charge transfer in semiconductor-electrolyte solar cells, highlighting the importance of detailed electrolyte modeling for accurate predictions.

Contribution

It introduces a coupled reaction-drift-diffusion-Poisson system for semiconductor-electrolyte dynamics, advancing the modeling accuracy over simplified approaches.

Findings

Numerical simulations demonstrate the model's ability to capture system behavior under different lighting conditions.

Replacing the electrolyte with a Schottky contact is only valid at very high reductant-oxidant densities.

The model provides insights into charge transfer mechanisms critical for solar cell design.

Abstract

The mathematical modeling and numerical simulation of semiconductor-electrolyte systems play important roles in the design of high-performance semiconductor-liquid junction solar cells. In this work, we propose a macroscopic mathematical model, a system of nonlinear partial differential equations, for the complete description of charge transfer dynamics in such systems. The model consists of a reaction-drift-diffusion-Poisson system that models the transport of electrons and holes in the semiconductor region and an equivalent system that describes the transport of reductants and oxidants, as well as other charged species, in the electrolyte region. The coupling between the semiconductor and the electrolyte is modeled through a set of interfacial reaction 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.