The Thermodynamic Limit of Indoor Photovoltaics Based on Energetically-Disordered Semiconductors

The coming decades are expected to see the advent of the ubiquitous "Internet-of-Things", through which countless networked devices and sensors will share immense quantities of information to benefit society as a whole. Among the energy harvesting techniques that could power the Internet-of-Things, indoor photovoltaics have shown considerable promise. However, the unique spectra of artificial light sources present numerous challenges, including determining the optimal bandgap, which varies from source to source but is generally larger than the bandgaps of conventional semiconductors like silicon. In this regard, organic semiconductors are particularly desirable for indoor applications due to their tailorable optical properties. Organic semiconductors, however, are not yet optimized for such applications. In this work, we explore how non-radiative open-circuit voltage losses, sub-optical gap absorption, and energetic disorder detrimentally affect the indoor performance of organic semiconductors. Following this we present a realistic upper estimate for the power conversion efficiency (PCE). Finally, we describe a methodology (accompanied by a computational tool with a graphical user interface) for predicting indoor organic photovoltaic performance under arbitrary illumination conditions. Using this methodology, we provide benchmarks for organics in indoor settings, before estimating the PCEs of several photovoltaic materials, including the state-of-the-art systems PM6:Y6 and PM6:BTP-eC9.