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The main obstacles to promoting the commercialization of perovskite solar cells (PSCs) include their record power conversion efficiency (PCE), which still remains below the Shockley–Queisser limit, and poor long‐term stability, attributable to crystallographic defects in perovskite films and open‐circuit voltage (Voc) loss in devices. In this study, potassium (4‐tert‐butoxycarbonylpiperazin‐1‐yl) methyl trifluoroborate (PTFBK) was employed as a multifunctional additive to target and modulate bulk perovskite defects and carrier dynamics of PSCs. Apart from simultaneously passivating anionic and cationic defects, PTFBK could also optimize the energy‐level alignment of devices and weaken the interaction between carriers and longitudinal optical phonons, resulting in a carrier lifetime of greater than 3 μs. Furthermore, it inhibited non‐radiative recombination and improved the crystallization capacity in the target perovskite film. Hence, the target rigid and flexible p‐i‐n PSCs yielded champion PCEs of 24.99 % and 23.48 %, respectively. More importantly, due to hydrogen bonding between formamidinium and fluorine, the target devices exhibited remarkable thermal, humidity, and operational tracking at maximum power point stabilities. The reduced Young's modulus and residual stress in the perovskite layer also provided excellent bending stability for flexible target devices. [ABSTRACT FROM AUTHOR]

In recent years, the surface modification of perovskite by wide band‐gap insulating materials has been one of the main strategies to achieve efficient and stable perovskite solar cells (PSCs). Unfortunately, a significant hurdle in this approach is the dilemma surrounding the quality of passivation and the transport of charges. Here, this trade‐off is overcome by introducing self‐assembled diphenylphosphinic acid (DPPA) porous layer. Applying highly concentrated DPPA solution on the perovskite surface not only provides excellent passivation of entire surface, but also the excess DPPA will form a self‐assembled porous insulating layer (PIL), which forms random submicron‐sized openings at the interface of the insulating layer for accelerated charge transport. In addition, the energy level of the perovskite surface can be modulated by this insulating material to facilitate carrier transport. As a result, an impressive power conversion efficiency (PCE) over 24% has been achieved in methylammonium‐free p‐i‐n devices with an ultrahigh fill factor (FF) of 84.7%. The unencapsulated devices exhibit excellent thermal and operational stability. This work paves a way for establishment of an effective passivation and facilitated transport simultaneously. [ABSTRACT FROM AUTHOR]