Narrow-bandgap tin-lead (Sn-Pb) mixed perovskite solar cells (PSCs) play a key role in constructing perovskite tandem solar cells that are potential to overpass Shockley-Queisser limit. A robust, chemically stable and lowtemperature-processed hole transporting layer (HTL) is essential for building high-efficiency Sn-Pb solar cells and perovskite tandem solar cells. Here, we explore a roomtemperature-processed NiO_x (L-NiO_x) HTL based on nanocrystals (NCs) for Sn-Pb PSCs. In comparison with hightemperature-annealed NiO_x (H-NiO_x) film, the L-NiO_x film shows deeper valence band and lower trap density, which increases the built-in potential and reduces carrier recombination, leading to a power conversion efficiency of 18.77%, the record for NiO_x-based narrow-bandgap PSCs. Furthermore, the device maintains about 96% of its original efficiency after 50 days. This work provides a robust and room-temperatureprocessed HTL for highly efficient and stable narrow-bandgap PSCs.

窄带隙锡铅（Sn-Pb）混合钙钛矿太阳能电池（PSC）在构建钙钛矿串联太阳能电池中可能发挥重要作用，钙钛矿串联太阳能电池有可能超过Shockley-Queisser极限。坚固，化学稳定且经过低温处理的空穴传输层（HTL）对于构建高效的Sn-Pb太阳能电池和钙钛矿串联太阳能电池至关重要。在这里，我们探索基于纳米晶（NCs）的Sn-Pb PSC的室温处理NiO _x（L-NiO _x）HTL。与高温退火的NiO _x（H-NiO _x）膜相比，L-NiO _x该膜显示出更高的价带和更低的陷阱密度，从而增加了内在电势并减少了载流子复合，从而导致功率转换效率达到18.77％，这是基于NiO _x的窄带隙PSC的记录。此外，该设备在50天后仍保持其原始效率的96％。这项工作为高效，稳定的窄带PSC提供了一个强大且经过室温处理的HTL。