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Chirality‐induced spin selectivity observed in chiral 2D organic–inorganic hybrid perovskite holds promise to achieve spin‐dependent electrochemistry. However, conventional chiral 2D perovskites suffer from low conductivity and hygroscopicity, limiting electrochemical performance and operational stability. Here, a cutting‐edge material design is introduced to develop a stable and efficient chiral perovskite‐based spin polarizer by employing fluorinated chiral cation. The fluorination approach effectively promotes the charge carrier transport along the out‐of‐plane direction by mitigating the dielectric confinement effect within the multi‐quantum well‐structured 2D perovskite. Integrating the fluorinated cation incorporated spin polarizer with BiVO4 photoanode considerably boosts the photocurrent density while reducing overpotential through a spin‐dependent oxygen evolution reaction. Furthermore, the hydrophobic nature of fluorine in spin polarizer endows operational stability to the photoanode, extending the durability by 280% as compared to the device with non‐fluorinated spin polarizer. [ABSTRACT FROM AUTHOR]

Chiral perovskites are promising materials due to their unique ability to interact with circularly polarized light (CPL), offering great potential in advanced photonic and spintronic applications. However, specific design principles for highly chiroptically active chiral perovskites remain unclear, hindering their practical exploitation. In this study, chiral cation fluorinated isomerization approach is employed to enhance the chiroptical response of chiral perovskites. Specifically, it is systematically discovered that incorporating ortho‐fluorinated chiral cations instead of para‐fluorinated cations induces a strong organic–inorganic halogen–halogen interaction due to the unique spatial arrangement. This boosted chirality transfer, mediated by the strong halogen–halogen interaction, resulting in a fivefold improvement in the circular dichroism compared to its para‐fluorinated counterpart. Consequently, a CPL photodetector utilizing the ortho‐fluorinated chiral perovskite exhibited superior CPL distinguishability of 0.288, the highest value among 2D lead‐iodide perovskite‐based devices. Furthermore, the photodetector incorporating these structural isomers demonstrated extended operational stability as well as high photodetecting performance. [ABSTRACT FROM AUTHOR]

Chiral perovskites have emerged as promising next‐generation materials for polarization detection due to their excellent circularly polarized light (CPL) detection capabilities. However, they suffer from a low chiroptical response when fabricated as a polycrystalline thin film, limiting their potential range of applications. Herein, it is demonstrated that antisolvent dripping during the spin‐coating process can effectively improve the chiroptical properties of polycrystalline chiral perovskite thin films. Systematic analysis with different antisolvents reveals that the highly polar antisolvent chloroform interacts with dimethyl sulfoxide molecules via hydrogen bonding. This strong hydrogen bonding suppresses the formation of intermediate and secondary phases and accelerates the crystallization of chiral 1D perovskites, thus reducing the density of the iodine vacancies inside the perovskite thin films. The lower density of iodine vacancies also intensifies the asymmetric tilting inorganic distortion of PbI6 octahedrons, enhancing the chiroptical response of the fabricated chiral perovskite material. Photodetectors based on the chloroform‐treated chiral perovskite films achieve a remarkably high distinguishability of 0.31, outperforming previously reported photodetectors based on the chiral perovskites. The fabricated photodetectors also exhibit outstanding responsivity and detectivity with enhanced operational stability. [ABSTRACT FROM AUTHOR]

Recently, lead halide perovskites have attracted significant attention as promising absorber materials for photoelectrochemical (PEC) solar water splitting. However, charge‐accumulation‐induced ion migration at the interface causes perovskite degradation and efficiency loss. To suppress the charge accumulation and improve the PEC performance of the perovskite photoanode, a simple interface engineering is proposed by decorating the SnO2/perovskite interface with a mixture of polyethylenimine ethoxylated (PEIE) and chlorobenzenesulfonic acid (CBSA). The mixed CBSA+PEIE treatment effectively passivates the oxygen vacancies in SnO2 and adjusts the band alignment between SnO2 and the perovskite. The synergistic effects of the mixture treatment facilitate an effective carrier extraction at the SnO2/perovskite interface, enhance the PEC performance, and improve the stability of the device. The perovskite photoanode exhibits an impressive applied bias photon‐to‐current efficiency of 12.9% with an outstanding durability for 225 h. Furthermore, an unbiased solar water splitting is achieved using all the perovskite photoelectrodes, resulting in a remarkable unassisted solar‐to‐hydrogen efficiency of 10.9% and a continuous 22 h stable operation. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) as a half‐anodic reaction of water splitting hinders the overall reaction efficiency owing to its thermodynamic and kinetic limitations. Iodide oxidation reaction (IOR) with low thermodynamic barrier and rapid reaction kinetics is a promising alternative to the OER. Herein, we present a molybdenum disulfide (MoS2) electrocatalyst for a high‐efficiency and remarkably durable anode enabling IOR. MoS2 nanosheets deposited on a porous carbon paper via atomic layer deposition show an IOR current density of 10 mA cm–2 at an anodic potential of 0.63 V with respect to the reversible hydrogen electrode owing to the porous substrate as well as the intrinsic iodide oxidation capability of MoS2 as confirmed by theoretical calculations. The lower positive potential applied to the MoS2‐based heterostructure during IOR electrocatalysis prevents deterioration of the active sites on MoS2, resulting in exceptional durability of 200 h. Subsequently, we fabricate a two‐electrode system comprising a MoS2 anode for IOR combined with a commercial Pt@C catalyst cathode for hydrogen evolution reaction. Moreover, the photovoltaic–electrochemical hydrogen production device comprising this electrolyzer and a single perovskite photovoltaic cell shows a record‐high current density of 21 mA cm–2 at 1 sun under unbiased conditions. [ABSTRACT FROM AUTHOR]

The lack of highly efficient photoanodes presents a significant challenge to implementing the promising strategy of unbiased solar‐to‐fuel conversion. To achieve high‐performance photoanodes, improving their light harvesting and charge separation/injection capabilities is indispensable. Herein, solution‐processed vertically oriented Sb2S3 nanorod arrays on substrate are obtained via a Au seed layer, resulting in improved optoelectronic properties (due to the light scattering effect) and favorable crystallographic orientation of the 1D nanostructure. Moreover, the (NH4)2WS4 treatment caps the surface of the nanorods with an amorphous WSx layer and passivates the sulfur vacancy of Sb2S3, resulting in boosted charge extraction to the reactants. The resulting photoanode is employed to drive an iodide oxidation reaction (IOR), which is a prominent alternative to sluggish water oxidation reactions, exhibiting a high photocurrent density of 13 mA cm−2 at 0.6 V versus the reversible hydrogen electrode. Subsequently, an unassisted hydrogen generation device is demonstrated by combining an Sb2S3 nanorod array‐based photoanode for IOR and a perovskite‐based photocathode for the hydrogen evolution reaction, achieving an efficient hydrogen production current density of 5.7 mA cm−2 without any external bias. [ABSTRACT FROM AUTHOR]

Antisolvent treatment has been developed to effectively fabricate dimethylammonium‐iodide (DMAI)‐assisted CsPbI3 perovskite solar cells (PSC) under moisture conditions. However, a clear understanding of its effect on the crystallization mechanism is still elusive. Here, the antisolvent bathing effect on DMAI‐assisted CsPbI3 crystallization is investigated under ambient conditions. For films bathed into antisolvents with Lewis basic oxygen (i.e., diethyl ether, anisole, ethyl acetate, and methyl acetate), rapid crystallization kinetics are observed due to the interaction between Cs4PbI6 and antisolvent in the form of the adduct. The Cs4PbI6‐antisolvent adduct lowers the transformation energy barrier, thereby enabling immediate phase transformation to CsPbI3 as soon as DMAPbI3 is decomposed. Based on this observation, a new crystallization mechanism is proposed for DMAI‐assisted CsPbI3 in which Cs4PbI6, instead of DMAPbI3, plays the role of the predominant phase of crystallization. Accelerated crystallization due to anisole antisolvent bathing results in a uniform film morphology and better coverage with fewer defects and pinholes. This enhances the power conversion efficiency of the n‐i‐p‐structured PSCs based on anisole‐bathed CsPbI3 to 18.84%, even under moisture conditions. [ABSTRACT FROM AUTHOR]

The rational design and strategy of obtaining stable bifunctional electrocatalysts with unique functionalities are prerequisite to achieving robust catalytic activity. In this study, a composition‐controlled partial sulfurization/phosphorization strategy to synthesize a doughnut‐like 3D heterostructured electrocatalyst for overall water splitting is proposed, wherein core–shell 2D CoS1−xPx nanosheets decorated with N‐doped carbon are self‐assembled to form a hierarchical 3D architecture. The composition and phase structure in core–shell CoS1−xPx can be readily modified by controlling the liquid phase sulfurization and subsequent phosphorization, thereby modifying the electronic structure and activating the intrinsic active sites. The resulting CoS1−xPx benefits from the unique structural features including high accessible active surface area, adequate amount of reactive sites, intimate interfacial coupling between the components, interconnected electron highway, and accelerated charge/mass transfer ability. Consequently, the optimized CoS0.46P0.54 electrocatalyst achieves a catalytic current density of 10 mA cm−2 at overpotentials as low as 101 and 302 mV for hydrogen evolution reaction and oxygen evolution reaction, respectively, with outstanding long‐term operational stability in alkaline solution. The CoS0.46P0.54 couple enables an alkaline water electrolysis with a current density of 10 mA cm−2 at a low cell voltage of 1.62 V, comparable to that of the RuO2||Pt/C couple (1.6 V). [ABSTRACT FROM AUTHOR]