Designing Nanostructures and Multilayers with Numerical Simulation for Efficient Solar Energy Conversion

Understanding light-semiconductor interaction is critical for the development of absorbers for efficient solar energy to electrical or chemical energy (fuel) conversion. Numerical simulation methods are often used to support experimental results and explain various optical phenomena in materials. Finite Difference Time Domain (FDTD) method has emerged as a tool for simulating and modelling different materials with unique optical properties (e.g. photonic band gap materials and plasmonic nanostructures). FDTD numerically solves partial differential equations by employing the central difference approximation. Through discretizing the Maxwells equations in time and space, the electric and magnetic fields can be solved iteratively at each step applying the Courant condition to achieve stability. Nonetheless, the method has not been proven effective in yielding an acceptable agreement between simulated optical properties including transmittance and reflectance and the experimental results for polycrystalline nanostructures and thin films. We have solved this problem by taking into account the grain boundary scattering effects. With our method, we could simulate the optical properties of semiconducting films and nanomaterials of different morphologies and dimensions used as absorbers in solar cells and PEC water splitting devices. The results obtained through simulations were in excellent agreement with those determined experimentally. In this presentation, we discuss the details of our model with examples of its effectiveness in designing unique nanostructured absorbers and multilayer devices for highly efficient solar energy conversion.