Despite the recent unprecedented development of efficient dopant‐free hole transporting materials (HTMs) for high‐performance perovskite solar cells (PSCs) on small‐area devices (≤0.1 cm2), low‐cost dopant‐free HTMs for large‐area PSCs (≥1 cm2) with high power conversion efficiencies (PCEs) have rarely been reported. Herein, two novel HTMs, 3,3′,6,6′ (or 2,2′,7,7′)‐tetrakis(N,N′‐di‐p‐methoxyphenylamine)‐N,N′‐bicarbazole (3,6 BCz‐OMeTAD or 2,7 BCz‐OMeTAD), are synthesized via an extremely simple route from very cheap raw materials. Owing to their excellent film‐forming abilities and matching energy levels, 3,6 BCz‐OMeTAD and 2,7 BCz‐OMeTAD can be successfully employed as a perfect ultrathin (≈30 nm) hole transporting layer in large‐area PSCs up to 1 cm2. The 3,6 BCz‐OMeTAD and 2,7 BCz‐OMeTAD based large‐area PSCs show highest PCEs up to 17.0% and 17.6%, respectively. More importantly, high performance large‐area PSCs based on 2,7 BCz‐OMeTAD retain 90% of the initial efficiency after 2000 h storage in an ambient environment without encapsulation.

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The preparation of high‐quality perovskite films is important for achieving high‐performance perovskite solar cells (PSCs). The effective balance between solvent and antisolvent is an essential factor for regulating high‐quality perovskite film during the spin‐coating and thermal‐annealing steps. In this work, a greener, nonhalogenated, nontoxic bifunctional (anti)solvent, methyl benzoate (MB), is developed not only as an antisolvent to rapidly generate crystal seeds at the perovskite spin‐coating step, but also as a digestive‐ripening solvent for the perovskite precursors, which can prevent the loss of organic components during the thermal‐annealing stage and effectively suppress the formation of miscellaneous lead halide phases. As a result, this novel bifunctional (anti)solvent is employed in planar n–i–p PSCs for engineering high‐quality perovskite layers and thus achieving a power conversion efficiency up to 22.37% with negligible hysteresis and >1300 h stability. Moreover, due to the high boiling point and low‐volatility characteristic of MB, high‐performance PSCs are achieved reproducibly at different operating temperatures (22–34 °C). Therefore, this developed bifunctional solvent system can provide a promising platform toward globally upscaling and commercializing PSCs in all seasons and regions.

Lead halide perovskites always emerge complex interactions among different elemental ions,w hichl ead to multiple intrinsic imperfections.E lemental defects,s uch as amine,P b, and Iv acancies at A-, B-, and X-sites,a re main issues to deteriorate perovskite solar cells (PSCs). Unfortunately,m ost previous passivators can only temporarily fix partial inactive vacancies as sacrificial agents.H erein, we propose ar ecovery agent, ferrocene (Fc), which can form aone-dimensional perovskite with adequate steric cavities and suitable dissociation energy to recover all elemental defects backt oa ctive light-harvesting perovskites,a nd regenerate Fc itself meanwhile.Based on this perpetual chain-reaction cycle, corresponding PSCs maintain > 10 000-hour lifetime in inert condition and > 1000-hour durabilities under various extreme environments,i ncluding continuous 85 8 8Ch eating, 50 %r elative humidity wetting,and 1-sun light soaking.