Figure-of-merit for assessment of semitransparent solar cells

Semitransparent solar cells (ST-SCs) have emerged as a prominent energy harvesting technology that combines the benefits of transparency and light-to-electricity conversion. The biggest opportunities for ST-SCs lie in their integration as windows and skylights within energy-sustainable buildings or combining them with other solar cell technologies in tandem configuration. The performance of ST-SCs is mainly determined by the trade-off between the competing parameters of the capability to convert the light-to-electricity while allowing some part of it to pass through imparting transparency. Depending on the target application, the selection of ST-SCs is a tricky affair as some devices might offer high efficiency but compromise transparency and vice versa. In addition, this is again not helped by the fact that due to advancements in materials engineering, processing, and characterization, vastly different combinations of efficiency and transparency have been reported. So to quantify the performance of ST-SCs, we attempted and developed a figure-of-merit (FoM), which can be used as a tool that can help in analyzing and comparing the performance among various ST-SCs. The defined FoM focuses on the efficiency of the device, bifaciality factor, transmittance in the desired region, and that corresponding to 550 nm wavelength. Additionally, we have been shown how the proposed FoM can be correlated for tandem and building-integrated photovoltaics applications. Based on these resultant parameters, FoM is calculated and compared for different device architectures available in the literature. The proposed FoM shall serve as a meaningful guiding path to the researchers for the development of advanced ST-SCs.