Abstract：
The complete elimination of methylammonium (MA) cations in Sn-Pb composites can extend their light and thermal stabilities. Unfortunately, MA-free Sn-Pb alloyed perovskite thin films suffer from wrinkled surfaces and poor crystallization, due to the coexistence of mixed intermediate phases. Here, we report an additive strategy for finely regulating the impurities in the intermediate phase of Cs0.25FA0.75Pb0.6Sn0.4I3 and, thereby, obtaining high-performance solar cells. We introduced d-homoserine lactone hydrochloride (D-HLH) to form hydrogen bonds and strong Pb-O/Sn-O bonds with perovskite precursors, thereby weakening the incomplete complexation effect between polar aprotic solvents (e.g., DMSO) and organic (FAI) or inorganic (CsI, PbI2, and SnI2) components, and balancing their nucleation processes. This treatment completely transformed mixed intermediate phases into pure preformed perovskite nuclei prior to thermal annealing. Besides, this D-HLH substantially inhibited the oxidation of Sn2+ species. This strategy generated a record efficiency of 21.61%, with a Voc of 0.88 V for an MA-free Sn-Pb device, and an efficiency of 23.82% for its tandem device. The unencapsulated devices displayed impressive thermal stability at 85 °C for 300 h and much improved continuous operation stability at MPP for 120 h.
摘要：
Sn-Pb复合材料中甲基铵（MA）阳离子的完全消除可以扩展其光和热稳定性。不幸的是,无MA的Sn-Pb合金钙钛矿薄膜表面起皱，结晶不良，由于混合中间相的共存。这里,我们报告了一种添加剂策略，用于精细调节Cs0.25FA0.75Pb0.6Sn0.4I3和中间相中的杂质，因此，获得高性能太阳能电池。我们引入d-高丝氨酸内酯盐酸盐（D-HLH）与钙钛矿前体形成氢键和强Pb-O/Sn-O键，从而削弱极性非质子溶剂之间的不完全络合效应(例如，DMSO）和有机（FAI）或无机（CsI，PbI2和SnI2)组件，平衡它们的成核过程。在热退火之前，这种处理将混合的中间相完全转化为纯的预制钙钛矿核。此外,这种D-HLH基本上抑制了Sn2+物质的氧化。这一策略产生了创纪录的21.61%的效率，对于无MA的Sn-Pb器件，Voc为0.88V，其串联装置的效率为23.82%。
