Efficient indoor dye-sensitized solar cells based on TiO2 hollow sphere

The upcoming successful commercialization of dye-sensitized solar cells as is conditioned by the improvement of the device performance and durability. One of promising strategies exploited so far is co-sensitization, which involved the development of the dyes with high light absorption together with high expensive photovoltage redox mediators. Here, we propose a different strategy to improve ambient light harvesting capacity and durability using the three-dimensional hollow sphere architecture of the photoanode, commercial XY1b dye, and common iodide/triiodide redox electrolyte. Under 1000 lux illumination, TiO2 hollow spheres obtained by nearsupercritical solvothermal synthesis with tuning shell thickness provided a power conversion efficiency of 25.25%, which is a 56.6% increase comparable to dispersed nanoparticles used in classical dye-sensitized solar cells. Together with the dye loading capacity and light scattering efficiency, the TiO2 hollow spheres improved the long-term stability of the cell under indoor lighting conditions. Thus, even after 720 h of operation, the DSSC continued to provide a stable short-circuit current with a moderate increase, approximately 10% from the initial value.