Effects of Van der Waals Interactions on Excitonic Properties of Lead Halide Perovskite Photovoltaic Materials

Excitons dissociation and diffusion are among the key properties that determine the efficiency of light harvesting in photovoltaic materials. As representatives of a promising category of novel photovoltaics, lead halide perovskites include both bonding and non-bonding interactions. In order to assess, and engineer, excitonic properties of these materials, theoretical calculations can complement experimental results to determine the effects of van der Waals interactions. The focus of this work is to utilize density functional theory simulations that explicitly incorporate van der Waals interactions to estimate excitonic properties. The results reveal how van der Waals interactions affect key excitonic characteristics, e.g., binding energies and effective masses, and help determine strategies for constituent selection towards improving light-harvesting efficiency.