In-depth understanding of the energy loss and efficiency limit of dye-sensitized solar cells under outdoor and indoor conditions

Indoor photovoltaics (IPVs) have attracted great attention due to their potential applicability as a power source to the emerging Internet of Things (IoTs)-low power electronic devices equipped with sensors, actuators, and internet connectivity. Dye-sensitized solar cells (DSSCs) are well known for their environmental friendliness and high efficiency under indoor conditions, as they show strong absorbance in the visible light range. However, DSSC efficiency under one sun conditions has not shown significant improvements in the last decade. Considering this context, herein, energy loss factors in DSSCs are thoroughly investigated and the feasible efficiency limits in DSSCs are calculated based on some assumptions under outdoor and indoor conditions and compared with the SQ limit of an ideal solar cell. The feasible efficiency limit of DSSCs under these assumptions under one sun conditions is 23.78% at a band gap of 1.34 eV. However, under indoor light conditions, the maximum feasible PCE for DSSCs is 35-41% compared to 50-58% for an SQ ideal solar cell at an absorber band gap between 1.82 and 1.96 eV. The possible Jsc and Voc of DSSCs under indoor conditions are in the range of 98-317.12 μA cm-2 and 0.93-1.41 V, respectively, and are 109-352.35 μA cm-2 and 1.08-1.55 V, respectively, for SQ ideal solar cells under different light sources of illuminance 1000 lux. Furthermore, DSSCs under indoor conditions (1000 lux) could provide a maximum power intensity of >100 μW cm-2, suggesting the suitability of IDSSCs for activating IoT devices in a smart house.