Light capacitances in silicon and perovskite solar cells

The framework on which the physics of silicon solar cells (SiSCs) is based robustly predicts dependences of capacitance on light intensity and voltage, even when most recent innovations are considered as the incorporation of transition metal oxide/Si heterojunctions. However, perovskite solar cells (PSCs) challenge most of the established paradigms, claiming for rethinking of known theories and devising novel models. Here we tackle this scenario by probing and comparing light-induced capacitance responses yielded by these two major exponents in the field of photovoltaic research. SiSCs light capacitances can be easily interpreted in the framework of the so-called chemical capacitance. Latest approaches addressing the intriguing low-frequency capacitive features of PSCs are outlined and compared. Here, apparent similarities and differences between both photovoltaic technologies are highlighted, concerning the observation of light capacitances of chemical origin. It is concluded that, contrary to that occurring in SiSCs, bulk electronic chemical capacitances are not straightforwardly observed in PSCs. As capacitive features exhibited by PSCs are believed to be critically connected to performance degradation and device instability, future research and explanation directions are proposed here for advancing in the understanding of this challenging photovoltaic technology.