4:15 PM - 4:30 PM
▲ [11p-N322-12] High Efficiency Lead-free Wide Bandgap Perovskite Solar Cells via Guanidinium Bromide Incorporation
Keywords:Wide-bandgap, lead free, A site engineering
Despite lead halide perovskite(top)/silicon(bottom) tandem solar cell achieving >29% efficiency, the toxicity of lead limits the adoption of perovskites in electronic devices. To solve this problem, tin perovskite has been suggested as an alternative candidate to be used as the top cell. However, most of the reports on tin perovskite solar cells are based on narrow bandgap materials (band gap: 1.20-1.40 eV), which are not suitable to be used as tandem top cell. In addition, the efficiency of previously reported wide-bandgap lead-free perovskites is not satisfactory showing less than 2.00 %. This study explores the fabrication of wide-bandgap (1.61 eV) ASnI2Br perovskite solar cells through optimization of formamidinium and guanidinium content to improve efficiency from 1.68% to 7.00%. Substituting the A site with larger cation resulting in larger crystal size which translated into higher device stability. Better energy level alignment within the device significantly enhanced the charge injection and extraction which translates into higher open-circuit voltage. This work provides proof that tin-halide perovskite solar cells have the potential in the fabrication of lead-free all-perovskite tandem solar cells.