The defective bottom interfaces of perovskites and hole-transport layers (HTLs) limit the performance of p-i-n structure perovskite solar cells. We report that the addition of lead chelation molecules into HTLs can strongly interact with lead(II) ion (Pb ²⁺ ), resulting in a reduced amorphous region in perovskites near HTLs and a passivated perovskite bottom surface. The minimodule with an aperture area of 26.9 square centimeters has a power conversion efficiency (PCE) of 21.8% (stabilized at 21.1%) that is certified by the National Renewable Energy Laboratory (NREL), which corresponds to a minimal small-cell efficiency of 24.6% (stabilized 24.1%) throughout the module area. Small-area cells and large-area minimodules with lead chelation molecules in HTLs had a light soaking stability of 3010 and 2130 hours, respectively, at an efficiency loss of 10% from the initial value under 1-sun illumination and open-circuit voltage conditions.

A high-quality hybrid Cs_0.15FA_0.85PbI₃ thin film is deposited through doping of carbon nanodots (CNDs) into perovskite precursor solution. The corresponding inverted planar perovskite solar cells (PSCs) of ITO/PTAA/Cs_0.15FA_0.85PbI₃/PC₆₁BM/BCP/Ag exhibit an improvement in efficiency from 17.36% to 20.06%, which could be attributed to the passivation of the defects at the crystallized perovskite thin film and enhanced perovskite phase uniformity. The results of electron trap density indicate that the addition of CNDs significantly reduces the defects density at the perovskite thin film and the recombination of charge carriers in transport process is minimized. These results demonstrate that low-cost CNDs are effective additives for passivating defects, further reducing charge carrier recombination and improving device efficiency.

It remains challenging to fabricate high‐efficiency all‐inorganic perovskite solar cells (PSCs) at low temperature. Herein, the low‐temperature preparation of high‐efficiency CsPbI₃ PSCs using hydroiodic acid (HI) and deionized water (H₂O) as additives at synthetic temperature as low as 100 °C is proposed, which is beneficial for constructing even more complicated tandem or flexible solar cells. The additive of HI facilitates CsPbI₃ to form a high‐quality and smooth perovskite film at low temperature. The addition of an optimal amount of H₂O further induces perovskite growth with larger grains and a smoother surface by the dissolution and recrystallization process in the grain boundary, which can suppress defects‐induced nonradiative recombination. In this scenario, the corresponding device with structure of ITO/PEDOT:PSS/CsPbI₃/PC₆₁BM/Ag exhibits a high power conversion efficiency of 11.41% and the fill factor is increased from 62% to about 69%, compared with device based on CsPbI₃ film without extra H₂O treatment. The appropriate amount of H₂O promotes the high‐quality multigrain growth of the CsPbI₃ film and reduces the internal defects, contributing to a significant improved charge collection efficiency. Therefore, this research work has paved a significant way to improving the quality of the all‐inorganic perovskite film for highly efficient solar cells.