How good can 2D excitonic solar cells be?

Excitonic semiconductors have been a subject of research for photovoltaic (PV) applications for many decades. While organic photovoltaics have now exceeded 19% power conversion efficiency (PCE), the advent of inorganic semiconductors such as two-dimensional transition metal dichalcogenides (TMDCs) has renewed interest in excitonic solar cells due to their sub-nm film thicknesses. While several reports have been published on TMDC-based photovoltaics, achieving PCEs higher than 6% has remained challenging. In this study, we perform a comprehensive analysis of the optical and electronic characteristics of TMDC-based excitonic PV devices. Our designs are consciously chosen with the consideration of manufacturing challenges associated with large-area photovoltaic technologies. Our analysis suggests that whereas the PCE for 2D excitonic solar cells may be limited to <13%, a specific power >100 W g(-1) may be achieved with our proposed designs, making them attractive in aerospace applications, distributed remote sensing, and wearable electronics.