Past Event: CSEM Student Forum

Modeling and Simulation of Semiconductor-Electrolyte Solar Cells

Michael Harmon, ICES, The University of Texas at Austin

Abstract

Semiconductor-electrolyte solar cells are devices which use sunlight to convert electrolytes (such as water) into fuel cells . In recent years, there has been an increased need for simulation tools in designing efficient semiconductor-electrolyte solar cells to harvest sunlight for clean energy. In the work by He. et al., the authors proposed a macroscopic mathematical model consisting of a system of nonlinear partial differential equations for the complete description of charge transfer dynamics in such semiconductor-electrolyte systems. The model consists of a reaction-drift-diffusion-Poisson 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. Numerical simulations of semiconductor-electrolyte solar cells based this model are a non-trivial task. The reaction-drift-diffusion-Poisson system used to model each component of the cell is highly nonlinear. The coupling of the equations for the semiconductor with the equations for the electrolyte through the interface makes the full system stiff. Moreover, sharp potential and density gradients can develop around the interface creating further challenges. In this talk I will discuss the modeling of semiconductor-electrolyte solar cells and the numerical methods use to simulate their dynamics. These method include mixed finite element methods and local discontinuous Galerkin method for the reaction-drift-diffusion-Poisson equations, as well as Schwarz domain decomposition methods to deal with the non-linear interface conditions. Preliminary results from simulations and future directions for my research will be presented.