Bias-free photoelectrochemical devices provide a sustainable route for solar hydrogen production from alkaline seawater, however, the requirement for large potential for anodic oxygen evolution and undesired chloride oxidation in seawater limit their efficiency. By leveraging the low oxidation potential of hydrazine, a toxic pollutant, bias-free devices can achieve high-performance hydrogen production and simultaneous degradation of hydrazine, effectively avoiding chloride oxidation. Here, we design a self-powered artificial leaf device, comprising a perovskite photocathode integrated with a noble-metal-free oxide catalyst for direct solar hydrogen production and hydrazine oxidation. The device exhibits a high photocurrent density of 25 mA cm-2 and stability for 3 days under 1-sun illumination. Upscaling the artificial leaf device enables near-complete hydrazine degradation to below 1 ppb within ≈ 30 h under zero-bias operation. This study provides a scalable and sustainable approach for simultaneous hydrogen generation and pollutant removal, advancing the use of solar energy in environmental applications.

Kesterite Cu2ZnSnS4 (CZTS) is a promising material for solar energy harvesting due to its high absorption coefficient and favorable electrical properties. However, its performance as a photocathode for photo-electrochemical (PEC) water splitting is limited by deep defects and poor interfacial charge transport. While partial substitution of Zn with Cd has shown improvements in PEC performance by reducing antisite defects, the impact of fully substituting Zn with Cd in CZTS-based devices remains underexplored due to challenges in forming high quality films. This study successfully fabricates fully cadmium-substituted CZTS (Cu2CdSnS4, CCTS) films by precisely controlling the Cu/(Cd + Sn) ratio in the precursor solution. Films with a Cu/(Cd + Sn) ratio of 0.9 demonstrate optimal quality, achieving a photocurrent of 25 mA cm-2 at 0 VRHE and a half-cell solarto-hydrogen conversion efficiency of 4.36 %-among the highest reported for chalcogenide photocathodes. These results stem from a suitable band gap, reduced defect concentration, lower charge transfer resistance, and favorable interfacial band alignment, as supported by Density Functional Theory, impedance spectroscopy, and ultraviolet photoelectron spectroscopy. This work highlights the importance of compositional optimization in maximizing PEC performance of CCTS photocathodes, establishing CCTS as a leading candidate among emerging chalcogenides for solar water splitting applications.

Achieving fully transparent electronic devices requires improving p-type transparent conducting materials (TCMs) to match their n-type counterparts. This study explores novel p-type TCMs using high-throughput screening via an automatic spray pyrolysis system. The performance of conducting wide bandgap chalcogenide based on CuS can be improved by incorporating various cations, with Mg emerging as the most promising candidate. The optimized CuS-Mg films exhibited superior transparency and conductivity, comparable to state-of-the-art p-type TCMs. Density functional theory (DFT) calculations linked the inverse correlation between transparency and conductivity to changes in Cu 3d and S 3p orbital coupling with varying Mg content. The best CuS-Mg composition demonstrated high hole concentration (5 × 1021 cm-3), low sheet resistance (266 Ω □-1), and high transparency (∼75%). The transmittance increased by ∼30% compared with pristine CuS. The successful application of a p-CuS-Mg/n-CdS heterojunction as a semi-transparent photodiode highlights its potential for smart displays and window-integrated electronics. This study demonstrates the value of combining experimental and theoretical methods for accelerated material discovery.

Alkali doping has been widely employed to enhance the performance of chalcopyrite and kesterite solar cells; however, its potential for Cu2CdSnS4 (CCTS) solar cells remains unexplored. This study systematically investigates the impact of all alkali dopants (Li, Na, K, Rb, Cs) on CCTS solar cells, providing new insights into their interaction with the CCTS structure and its subsequent impact on optoelectronic properties. Alkali doping increases carrier density by an order of magnitude without introducing detrimental recombination centres, as highlighted by the stable minority carrier lifetime. Kelvin probe force microscopy (KPFM) reveals a reduction in upward band bending at grain boundaries, minimizing majority carrier accumulation and enhancing carrier transport. Conductive-atomic force microscopy (c-AFM) further demonstrates an enhancement in intragrain conductivity, with nanoscale surface current increasing by an order of magnitude. Among the doped samples, Na-doped CCTS achieves the highest efficiency of 8.47%, attributed to its compact film morphology and improved charge transport, which collectively yield a higher fill factor and JSC. These findings establish alkali doping as a promising strategy for optimizing CCTS solar cells, with Na emerging as the most effective dopant to enhance device performance.

Partial Mo 6+ leaching selectively activates Ni 2+ in NiCo 2− x Mo x O 4 , forming NiOOH, to enhance OER. When integrated into a water electrolyzer powered by a p-i-n perovskite solar cell, the system enables bias-free solar H 2 production at 8.8% efficiency.

Circularly polarized luminescence (CPL) is important for multiple photonic technologies. It can be achieved with high asymmetry factors ( g lum ) by combining quantum emitters (QEs) with one‐dimensional helical superstructures (1D‐HS). However, existing 1D‐HS systems face challenges of maintaining polarization purity across viewing angles, primary due to the mismatch between QE emission profiles and the photonic bandgap of 1D‐HS across off‐normal directions. Herein, efficient and controllable CPL is proposed and developed using the self‐assembly of colloidal quantum wells (CQWs) coupled with cholesteric liquid crystals (CLCs). The face‐down CQWs assemblies with over 90% in‐plane transition dipole moments enables directional emission along the liquid crystal helical axis within the light escape cone. At the same time aligning their narrow emission spectra to the edge of the CLCs reflection band significantly enhances the spectral coupling. This results in highly efficient CPL with an improved g lum of 1.47–1.82 (±0.03) over an expanded viewing range (±40°) and a large increase (53.3%) in extraction efficiency, supported by comprehensive angle‐resolved and wavelength‐resolved spectroscopy as well as optical simulations. Moreover, this approach facilitates the development of novel anti‐peeping and angle‐dependent luminescent devices. This work establishes a versatile platform for spatially homogeneous and tunable CPL in next‐generation photonic systems.

The development of high-performance p-type transparent conducting materials remains a challenge in advancing next-generation transparent electronics and solar harvesting devices. Among potential candidates, LaCuOS has demonstrated exceptional performance. However, its conventional synthesis typically relies on costly vacuum-based techniques such as sputtering and pulsed laser deposition, often requiring hazardous H _2 S gas. Here, we report a facile and scalable spray pyrolysis method for fabricating high-performance p-type LaCuOS thin films—eliminating the need for toxic H _2 S and reducing production costs. The optimized films achieve a remarkable electrical conductivity of 1659.2 S · m ^−1 . This enhancement is attributed to a novel adjustment of the Cu/La ratio, which promotes the formation of a well-blended CuS phase that improves hole concentration and mobility. With minimal optical transmittance loss, the film exhibits a Gordon’s figure of merit of 1.26 × 10 ^−3 Ω ^−1 and a Haacke’s figure of merit of 2.97 × 10 ^−6 Ω ^−1 —ranking among the highest values reported for LaCuOS and surpassing those achieved using more complex and expensive methods. This work highlights spray pyrolysis as a scalable, safe, and cost-effective approach for producing high-performance LaCuOS, with the added benefit of precise compositional tuning via simple precursor solution adjustments.

Systematic alkali dopant selection tunes Cu 2 CdSnS 4 thin film properties, revealing suppressed recombination, optimal charge transport, and improved solar cell performance.

Despite the remarkable efficiency of perovskite solar cells (PSCs), long-term stability remains the primary barrier to their commercialization. The prospect of enhancing stability by substituting organic transport layers with suitable inorganic compounds, particularly Cu-based inorganic hole-transport materials (HTMs), holds promise due to their high valence band maximum (VBM) aligning with perovskite characteristics. This review assesses the advantages and disadvantages of these five types of Cu-based HTMs. Although Cu-based binary oxides and chalcogenides face narrow bandgap issues, the "chemical modulation of the valence band" (CMVB) strategy has successfully broadened the bandgap for Cu-based ternary oxides and chalcogenides. However, Cu-based ternary oxides encounter challenges with low mobility, and Cu-based ternary chalcogenides face mismatches in VBM alignment with perovskites. Cu-based binary halides, especially CuI, exhibit excellent properties such as wider bandgap, high mobility, and defect tolerance, but their stability remains a concern. These limitations of single anion compounds are insightfully discussed, offering solutions from the perspective of practical application. Future research can focus on Cu-based composite anion compounds, which merge the advantages of single anion compounds. Additionally, mixed-cation chalcogenides such as CuxM1-xS enable the customization of HTM properties by selecting and adjusting the proportions of cation M.

Copper-chalcogenide-based inorganic holetransport layers (HTLs) are widely studied in perovskite solar cells (PSCs) because of their favorable valence band maximum and their ability to passivate interfacial defects through Pb-S interactions. These compounds are shown to produce stable PSCs because of their high intrinsic stability. However, the density functional theory (DFT) calculations and X-ray photoelectron spectroscopy analysis presented here reveal that the presence of Cu in the HTL can weaken the interfacial Pb-S interactions and compromise the device stability. A clear inverse relationship is observed between the stability of perovskite film and the Cu-concentration in the HTL underneath. Therefore, to minimize the detrimental effect of Cu, this work explores Cu-deficient chalcopyrite compounds, CuIn3S5 and Cu(InxGa(1-x))(3)S-5, as HTLs for PSCs, which results in improved device stability. DFT calculations reveal that incorporating gallium into the HTL reduces the HTL-perovskite interfacial energy, which results in further enhancement of device stability. The average T-80 lifetimes (the time to retain 80% of the initial efficiency) under ambient conditions for the NiO, CuIn3S5, and Cu(In0.3Ga0.7)(3)S-5 HTL-based devices are 200, 449, and 656 h, respectively. These findings underscore the significant roles of cations and anions of the inorganic transport layer in enhancing the stability of the PSCs.

Chalcogenide-based Lewis bases are widely used in perovskite solar cells (PSCs) due to their effectiveness in passivating Pb2+ and Pb-0-related defects. However, the underlying principles governing their defect passivation and the relative efficacy of different chalcogen elements remain poorly understood. This study evaluates the effectiveness of oxygen, sulfur, and selenium-based interface passivator molecules in enhancing the stability and power conversion efficiency (PCE) of perovskite solar cell devices. The hard and soft acid and base (HSAB) principle has been utilized here to gain insights into the defect passivation behavior of chalcogenide-based molecules. The photoluminescence, ideality factor, and trap density measurements reveal that the sulfide and selenide-passivated devices exhibit superior defect passivation compared to the oxide-passivated control device. In terms of stability, the average T-75 lifetime (time at which 75% of the initial PCE is retained) of the oxide, sulfide, and selenide passivated samples is 6%, 30%, and 50% higher compared to their un-passivated counterparts. This enhanced stability with the sulfide and selenide-based passivators can be attributed to their soft Lewis base nature, which resulted in stronger interaction with the Pb-related defects, as evidenced by the density-functional theory calculations and X-Ray photoelectron spectroscopy study.

Significant advancements in the perovskite solar cells/modules (PSCs/PSMs) toward better operational stability and large area scalability have recently been reported. However, semitransparent (ST), high efficiency, and large area PSMs are still not well explored and require attention to realize their application in building‐integrated photovoltaics (BIPV). This work employs multiple synergistic strategies to improve the quality and stability of the ST perovskite film while ensuring high transparency. Europium ions, doped in the perovskite, are found to suppress the generation of detrimental species like elemental Pb and I, resulting in higher atmospheric stability. The effect of the top transparent contact is designed to obtain an average visible transparency (AVT) of >20% for full device and a green colored hue. Lastly, the lower current density due to the thinner ST absorber is enhanced by the application of a down‐converting phosphor material which harvests low energy photons and inhibits UV‐induced degradation. This multimodal approach renders a power conversion efficiency of 12% under dim light conditions and 9.5% under 1 sun illumination, respectively, on 21 cm2 ST‐PSM.

There is broad interest in developing photonically active substrates from naturally abundant, minimally processed materials that can help to overcome the environmental challenges of synthetic plastic substrates while also gaining inspiration from biological design principles. To date, most efforts have focused on rationally engineering the micro- and nanoscale structural properties of cellulose-based materials by tuning fibril and fiber dimensions and packing along with chemical modifications, while there is largely untapped potential to design photonically active substrates from other classes of natural materials with distinct morphological features. Herein, the fabrication of a flexible pollen-derived substrate is reported, which exhibits high transparency (>92%) and high haze (>84%) on account of the micro- and nanostructure properties of constituent pollen particles that are readily obtained from nature and require minimal extraction or processing to form the paper-like substrate based on colloidal self-assembly. Experiments and simulations confirm that the optical properties of the pollen substrate are tunable and arise from light-matter interactions with the spiky surface of pollen particles. In a proof-of-concept example, the pollen substrate is incorporated into a functional perovskite solar cell while the tunable optical properties of the intrinsically micro-/nanostructured pollen substrate can be useful for a wide range of optoelectronic applications.

Inorganic hole‐transport layers (HTLs) are widely investigated in perovskite solar cells (PSCs) due to their superior stability compared to the organic HTLs. However, in p–i–n architecture when these inorganic HTLs are deposited before the perovskite, it forms a suboptimal interface quality for the crystallization of perovskite, which reduces device stability, causes recombination, and limits the power conversion efficiency of the device. The incorporation of an appropriate functional group such as sulfur‐terminated surface on the HTL can enhance the interface quality due to its interaction with perovskite during the crystallization process. In this work, a bifunctional Al‐doped CuS film is wet‐deposited as HTL in p–i–n architecture PSC, which besides acting as an HTL also improves the crystallization of perovskite at the interface. Urbach energy and light intensity versus open‐circuit voltage characterization suggest the formation of a better‐quality interface in the sulfide HTL–perovskite heterojunction. The degradation behavior of the sulfide‐HTL‐based perovskite devices is studied, where it can be observed that after 2 weeks of storage in a controlled environment, the devices retain close to 95% of their initial efficiency.