Heavy pnictogens-based perovskite-inspired materials: Sustainable light-harvesters for indoor photovoltaics

The need for self-powered electronics is progressively growing in parallel with the flourishing of the Internet of Things (IoT). Although batteries are dominating as powering devices, other small systems, such as piezoelectric, thermoelectric, and photovoltaic systems, are attracting attention. These last ones can be adapted from their classical outdoor configuration to work preferentially under indoor illumination, i.e., by harvesting the spectrum emitted by LEDs and/or fluorescent lamps. However, crystalline silicon, the classical photovoltaic material for solar panels, has a bandgap not suitable for ensuring good efficiency with such spectra. With wider bandgaps, other semiconductors can come into play for this task. Still, the materials of choice, having to be integrated within households, should also satisfy the criterion of non-toxicity and maintain low-cost production. While lead-based halide perovskites cannot represent a valuable solution for this scope, due to the strong environmental and health concerns associated with the presence of Pb, analogous compounds based on the heaviest pnictogens, i.e., bismuth and antimony, could work as sustainable light-harvesters for indoor photovoltaic devices. In this Review, we focus on reporting the most recent developments of three compounds of this class: The double perovskite Cs2AgBiBr6 is first chosen as a model system for the other two, which are emerging perovskite-inspired materials, namely, Cs3Sb2I9−xClx and bismuth oxyiodide. We show the potential of these semiconductors to play a crucial role in the future market of self-powering IoT devices, which will become a large class of devices in the electronics industry in the upcoming years.