Self-Assembled\nMonolayer Hole Transport Layers for\nHigh-Performance and Stable Inverted Perovskite Solar Cells

NiO<sub><i>x</i></sub> is regarded as a kind\nof promising\nhole transport material in inverted perovskite solar cells (PSCs);\nhowever, the uncontrolled defects and unfavorable reactions within\nthe perovskite layer go against device stability and power conversion\nefficiency (PCE). The pristine NiO<sub><i>x</i></sub> hole\ntransport layer (HTL)-based PSCs usually require additional doping\nor interface engineering, which tends to introduce additional defects/sharp\ninterfaces and thus affect the device performance. In this study,\nMeO-2PACz, a type of self-assembled materials (SAMs), was chosen to\nreplace the standard NiO<sub><i>x</i></sub> as HTL and employed\nin inverted PSCs, since it possesses the potential for manufacturing\nhigh-performance stable PSCs. The results demonstrated that MeO-2PACz\ninteracts with uncoordinated Pb<sup>2+</sup> in the perovskite film,\neffectively passivating buried interface defects. Besides, the perovskite\nfilm deposited on MeO-2PACz HTL has improved crystallization quality\nand abated grain boundaries. Meanwhile, the good band alignment of\nthe MeO-2PACz HTL/perovskite interface minimizes nonradiative recombination\nloss at the interface, considerably boosting charge extraction/transport\nefficiency and device performance. Accordingly, the device based on\nMeO-2PACz HTL achieved a champion PCE of 21.61% with a fill factor\n(FF) of 82.30%, accompanied by good stability, maintaining 94.0% of\nits initial PCE after 3000 h storage in ambient air without encapsulation\nat 25 °C. Hopefully, this work presents a novel approach to overcome\nthe shortcomings of NiO<sub><i>x</i></sub> HTL-based PSCs,\nguaranteeing better performance.