Electronic structure and photovoltaic application of BiI3

Rapid recent improvement in photovoltaic efficiency in hybrid lead halide perovskite materials has provided the impetus for understanding other, related main-group halide systems. Here, we show that the closely related but less toxic bismuth iodide BiI3 can show promising optoelectronic properties. Layered binary BiI3 is used here as the active layer in planar solar cell architectures (efficiency approximately 0.3%). Experimental and computational studies of absolute band positions of BiI3 are also presented, to help in the rational design of device architectures that would allow efficient charge transfer at the interfaces.