Indoor light harvesting lead-free 2-aminothiazolium bismuth iodide solar cells

Bismuth (Bi) based solar cells have recently attracted significant attention in line with lead-free perovskite solar cells development. In this study, 2-aminothiazolium iodide (ATI) is used to prepare highly crystalline and environmentally stable lead free ATBiI ₄ photoactive thin films, which were comprehensively characterized for integration into planar solar cells with the n-i-p device architecture. The ATBiI ₄ solar cells delivered a power conversion efficiency of 0.53% with open-circuit voltage of 0.83 V under 1 sun, a 12.8% increase in the power conversion efficiency arising mainly due to 124% increase in the open circuit voltage as compared to the triple mesoscopic devices explored previously. Furthermore, in this study the solar cells have been explored for harvesting energy from indoor white light emitting diodes (LED) for the first time revealing a power output of 81.75 μW cm ⁻² at 500 lux. As ATBiI ₄ has its absorption maximum in the ultra-violet wavelength region, the solar cells have been further tested under 9 W UV LED (395-400 nm), which yielded a power output of 8.07 μW cm ⁻² at 150 lux. This work demonstrates that 2-aminothiazolium bismuth iodide solar cells are promising microwatt energy sources which can find potential application for powering smart electronics.