In this paper, oleylammonium polysulfides molecules were self-assembled on an etched perovskite film, leading to an enhancement in moisture stability of the devices.

Organometallic halide perovskite solar cells (PSCs) are rapidly evolving as the promising photovoltaic technologies with high record efficiency over 24%. The inorganic p‐type semiconductor NiOx is extensively used as important hole transport layers for the realization of stable and hysteresis‐free solar cells due to their good electronic properties, facile fabrication, and excellent chemical endurance. However, the critical issues of NiOx films including poor intrinsic conductivity and mismatched band alignment limit further improvement of the device performance. Herein, it is demonstrated that a versatile alkaline earth metal (Mg, Ca, Sr, and Ba) doping strategy can effectively engineer the electronic properties of NiOx contacts in inverted planar PSCs. Alkaline earth metal doping can deepen valence band maximum and enhance the hole conductivity of NiOx films, which better aligns the energy band in solar cells. The champion device based on Sr‐doped NiOx films attains a power conversion efficiency of 19.49% with a high open‐circuit voltage (VOC) of 1.14 V for NiOx‐based CH3NH3PbI3 devices. The resulted device shows negligible hysteresis and high stability as well. This finding provides a systematic doping strategy to further improve the performance of inverted planar PSCs.

Cesium lead halide perovskites are promising alternatives as light-absorbing materials for perovskite solar cells with excellent thermal stability, but their inferior power conversion efficiency (PCE) and ambient instability are impeding...

Passivation, as a classical surface treatment technique, has been widely accepted in start-of-the-art perovskite solar cells (PSCs) that can effectively modulate the electronic and chemical property of defective perovskite surface. The discovery of inorganic passivation compounds, such as oxysalts, has largely advanced the efficiency and lifetime of PSCs on account of its favorable electrical property and remarkable inherent stability, but a lack of deep understanding of how its local configuration affects the passivation effectiveness is a huge impediment for future interfacial molecular engineering. Here, we demonstrate the central-atom-dependent-passivation of oxysalt on perovskite surface, in which the central atoms of oxyacid anions dominate the interfacial oxygen-bridge strength. We revealed that the balance of local interactions between the central atoms of oxyacid anions (e.g., N, C, S, P, Si) and the metal cations on perovskite surface (e.g., Pb) generally determines the bond formation at oxysalt/perovskite interface, which can be understood by the bond order conservation principle. Silicate with less electronegative Si central atoms provides strong O-Pb motif and improved passivation effect, delivering a champion efficiency of 17.26% for CsPbI2Br solar cells. Our strategy is also universally effective in improving the device performance of several commonly used perovskite compositions.

Metal halide perovskite solar cells (PSCs) have emerged as one of the most promising photovoltaic technologies. For inverted planar PSCs, nickel oxide (NiOx) layers, as inorganic p‐type semiconductors, are competitive hole transport layers (HTLs) because of their low cost, chemical stability, and easy preparation. However, their inferior device performance still lags behind the devices using organic HTLs. Herein, a boric acid‐assisted strategy for NiOx HTLs is reported that enables compact film deposition and electronic modulation. Boron doping can enhance conductivity and deepen the valence band edge, leading to efficient hole extraction and transport. A methylammonium lead iodide (MAPbI3) photovoltaic device based on our strategy achieves an optimized efficiency of 21.40% with a high open voltage of 1.131 V and a high fill factor of 80.9% with negligible hysteresis, as well as excellent stability.