Owing to the ionic nature of lead halide perovskites, their halide-terminated surface is unstable under light-, thermal-, moisture-, or electric-field-driven stresses, resulting in the formation of unfavorable surface defects. As a result, nonradiative recombination generally occurs on perovskite films and deteriorates the efficiency, stability, and hysteresis performances of perovskite solar cells (PSCs). Here, a surface iodide management strategy was developed through the use of cesium sulfonate to stabilize the perovskite surface. It was found that the pristine surface of common perovskite was terminated with extra iodide, that is, with an I–/Pb2+ ratio larger than 3, explaining the origination of surface-related problems. Through post-treatment of perovskite films by cesium sulfonate, the extra iodide on the surface was facilely removed and the as-exposed Pb2+ cations were chelated with sulfonate anions while maintaining the original 3D perovskite structure. Such iodide replacement and lead chelating coordination on perovskite could reduce the commonly existing surface defects and nonradiative recombination, enabling assembled PSCs with an efficiency of 22.06% in 0.12 cm2 cells and 18.1% in 36 cm2 modules with high stability.

Perovskite solar cells (PSCs) with organic hole transporting layers (o-HTLs) have been widely studied due to their convenient solution processing, but it remains a big challenge to improve the hole mobilities of commercially available organic hole transporting materials without ion doping while maintaining the stability of PSCs. In this work, we demonstrated that the introduction of perovskite quantum dots (QDs) as interlayers between perovskite layers and dopant-free o-HTLs (P3HT, PTAA, Spiro-OMeTAD) resulted in a significantly enhanced performance of PSCs. The universal role of QDs in improving the efficiency and stability of PSCs was validated, exceeding that of lithium doping. After a deep examination of the mechanism, QD interlayers provided the multifunctional roles as follows: (1) passivating the perovskite surface to reduce the overall amount of trap states; (2) promoting hole extraction from perovskite to dopant-free o-HTLs by forming cascade energy levels; (3) improving hole mobilities of dopant-free o-HTLs by regulating their polymer/molecule orientation. What is more, the thermal/moisture/light stabilities of dopant-free o-HTLs-based PSCs were greatly improved with QD interlayers. Finally, we demonstrated the reliability of the QD interlayers by fabricating large-area solar modules with dopant-free o-HTLs, showing great potential in commercial usage.

As an inorganic hole transport material (HTM), nickel oxide (NiOx) is widely used in perovskite solar cells (PSCs) due to its low cost and intrinsic stability. However, on account of its poor film formation on perovskite, the low power conversion efficiency (PCE) and stability of regular NiOx‐based PSCs is a main obstacle for commercialization. Here, a solution‐processed inorganic/organic hybrid hole transporting system is developed to resolve this issue, thereby improving the PCE from 16.0% to 21.2%. Poly(3‐hexylthiophene) (P3HT) is studied as the typical case, revealing that the performance improvement mainly lies in the synergistic interaction between NiOx and P3HT: 1) the introduction of P3HT improves assembly regularity and film uniformity of NiOx; 2) electron redistribution between P3HT and NiOx increases the Ni3+/Ni2+ ratio for higher hole mobility; 3) the feed‐back impact of NiOx on P3HT enhances molecular orientation of polymer chains in P3HT for better hole transport through polymer framework. Finally, the encapsulated solar cell modules with P3HT‐promoted NiOx maintains 91% of the initial efficiency after 1000 h aging at a harsh 85 °C/85% relative humidity condition. This finding provides a feasible approach for using NiOx‐based HTMs to realize high‐performance regular PSCs, paving the way for their commercialization.