Multifunctional\nAcetaminophen Interlayer for High\nEfficiency and Durability Lead-Lean Perovskite Solar Cells

Due to the easy oxidation of Sn<sup>2+</sup>, which leads\nto form\ntin vacancy defects and poor perovskite film quality, caused by the\nrapid crystallization rate in tin-based perovskite solar cells (PSCs),\ntheir efficiency lags far behind that of lead-based PSCs. To improve\nthe photovoltaic (PV) performance and stability of FA<sub>0.9</sub>PEA<sub>0.1</sub>SnI<sub>3</sub>-based PSCs (T-PSCs), a small amount\nof Pb(SCN)<sub>2</sub> is introduced into a perovskite precursor as\nan antioxidant, and acetaminophen (ACE) with various functional groups\nis used to modify a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)\n(PEDOT:PSS)/perovskite interface. The results show that the Pb(SCN)<sub>2</sub> additive and ACE interfacial modification can not only optimize\nenergy level alignment in T-PSCs but also inhibit Sn<sup>2+</sup> oxidation\nto reduce the trap-state density, resulting in promoted carrier transport.\nThe synergetic effect of the Pb(SCN)<sub>2</sub> antioxidant and ACE\ninterfacial modification significantly reduces nonradiative recombination\nand improves the PV performance and stability of T-PSCs. Consequently,\nthe unsealed T-PSCs with the Pb(SCN)<sub>2</sub> additive and ACE\nmodification achieve a champion efficiency of 12.04% and maintain\n99% of their initial PCE after being stored in N<sub>2</sub> for more\nthan 2100 h, while reference T-PSCs demonstrate a champion PCE of\n6.20% and retain only 72% of its initial PCE. Moreover, the modified\nT-PSCs without encapsulation demonstrate much better stability in\nhumid air.