BiI3: A Lower Toxicity Route to Tandem Solar Cells

Abstract

Global population is expected to grow by more than 2 billion people by mid-century. This will result in a large increase in electricity demand. However, any efforts in increasing electricity generation must take into account the health and environmental risks presented by traditional carbon-based fuel sources. Emphasis must be placed on generating electricity from zero-emission sources in an effort to mitigate the effects of climate change. Photovoltaic (PV) electricity generation is one such zero-emission generation method. Highly efficient, cheap, and low toxicity PV materials will be required to address this. In this work, we present an exploration of BiI3 as a solution-processed, lower toxicity PV material. We show that BiI3 films with 1 eV quasi-Fermi level splitting can be obtained from optimal processing conditions. We also explore how and why the different processing conditions influence morphology and optoelectronic quality of BiI3 films. Finally, we discuss some of the limiting factors on achieving high efficiency BiI3 devices.