Organic‐inorganic lead halide perovskite are promising photovoltaic materials, but their intrinsic defects and crystalline quality severely deteriorate the solar cells efficiency and stability. Herein, potassium 1,1,2,2,3,3‐hexafluoroprop‐ane‐1,3‐disulfonimide (KHFDF) is introduced into PbI2 precursor solution to passivate various defects and improve the crystalline quality of perovskite films. It is found that KHFDF can inhibit PbI2 crystallization, thus tuning the crystal orientation and growth of perovskite films. Furthermore, KHFDF with dual‐functional sulfonyl group cannot only passivate grain boundaries (GBs), but also passivate the defects at GBs via strong interaction with undercoordinated Pb2+ and/or hydrogen bonding with FA+, while the K+ counter cations allow ionic interaction with undercoordinated I−. As a result, the KHFDF‐modified films exhibit high quality with a larger grain size and a reduced trap‐state density, thereby suppressing the trap‐state nonradiative recombination. And the devices show a champion efficiency up to 24.15%, benefiting from a sharp enhancement of open‐circuit voltage (Voc) of 1.183 V and fill factor of 81.78%. In addition, due to the enhanced humidity tolerance and chemical structure stability, the devices exhibit excellent long‐term humidity and thermal stability without encapsulation.

Photoelectrochemical (PEC) water splitting directly converts solar energy into clean and sustainable hydrogen energy, representing a promising and effective technique for solving the world's energy crisis. A hole transfer layer (HTL) plays a vital role for extracting holes from a semiconductor layer to a back electrode in PEC cells for water splitting. In this work, a TiOx/Sb2Se3/NiOx photocathode was fabricated by using p-NiOx as HTL. We show that the electrical properties of NiOx films can be well adjusted by the pulsed laser deposition technique. By systematically adjusting the electrical properties of the NiOx HTL and passivating the surface defects through coating with the TiOx layer, we achieved a high photocurrent density of up to −18.08 mA cm−2 at 0 V vs a reversible hydrogen electrode (RHE), an onset potential of 0.43 V vs RHE, and a half-cell solar to hydrogen conversion efficiency of 1.01% for the TiOx/Sb2Se3/NiOx photocathode. This work demonstrated NiOx as a potential hole transport material for a cost-effective Sb2Se3 PEC cell.

The effect of substitutional metal dopants in NiO x on the structural and electronic structures is of great interest, particularly for increasing the p-type conductivities as a hole transport layer (HTL) applied in perovskite solar cells (PSCs). In this paper, experimental fabrications and density functional theory calculations have been carried out on Cd-doped NiO x films to examine the effect of divalent doping on the electronic and geometric structures of NiO x . The results indicate that divalent Cd dopants reduced the formation energy of the Ni vacancy (VNi) and created more VNi in the films, which enhanced the p-type conductivity of the NiO x films. In addition, Cd doping also deepened the valence band edge, reduced the monomolecular Shockley–Read–Hall (SRH) recombination losses, and promoted hole extraction and transport. Hence, the PSCs with Cd:NiO x HTLs manifest a high efficiency of 20.47%, a high photocurrent density of 23.00 mA cm–2, and a high fill factor of 79.62%, as well as negligible hysteresis and excellent stability. This work illustrates that divalent elements such as Cd, Zn, Co, etc. may be potential dopants to improve the p-type conductivity of the NiO x films for applications in highly efficient and stabilized PSCs.

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Antimony selenide (Sb 2 Se 3 ) is a promising semiconductor lightabsorbing material for photoelectrochemical (PEC) water splitting to produce hydrogen. Effectively promoting the separation of photogenerated carriers and extracting holes from the light-absorbing layer to the back electrode are key to improving the PEC performance. In this work, the Sb 2 Se 3 /CuSbS 2 heterojunction was prepared by a facile and cost-effective method that involves solution synthesis, spincoating, and thermal treatment processes. The PEC performance of the Sb 2 Se 3 /CuSbS 2 heterojunction was optimized by adjusting the drying temperature of the prepared CuSbS 2 films. After surface passivation with TiO x , the Sb 2 Se 3 surface defects were passivated and the PEC devices were well protected, and the Pt/TiO x /Sb 2 Se 3 /CuSbS 2 / FTO photocathode possessed a photocurrent density of 18.0 mA cm −2 at 0 V versus reversible hydrogen electrode, about four times that without the CuSbS 2 layer. This excellent PEC performance benefits from the construction of heterojunctions with suitable energy band alignment and the improved electron−hole pair separation and transfer efficiency. This work provides an effective strategy and important guidelines for improving the PEC efficiency of the Sb 2 Se 3 photocathode by introducing CuSbS 2 to form a heterojunction.