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Organic–inorganic hybrid halide perovskites have emerged as the most promising optoelectronic materials for next‐generation solution‐processed devices, primarily attributed to their distinctive properties such as cost‐effectiveness, facile fabrication process, high light absorption coefficient, tunable bandgap, and relatively high charge carrier mobility. Nevertheless, the presence of Pb elements is inevitable in most high‐performance perovskite optoelectronic devices, posing environmental pollution concerns and impeding their commercialization. In this study, two novel non‐toxic bismuth‐ and antimony‐based perovskite materials with environmentally conscious approaches are developed. Their structures and optoelectronic properties have been systematically characterized. Subsequently, photoconductive‐ and photodiode‐type photodetectors are designed and fabricated. Notably, the photodiode configuration exhibits exceptionally low dark current and noise, superior detection sensitivity, fast response speed, and good device stability. Owing to these superior performance metrics, the devices demonstrate great potential for real applications. Furthermore, this study furnishes a theoretical framework and design perspectives for the solution‐processed semiconductor materials. [ABSTRACT FROM AUTHOR]

Metal halide perovskites are promising light absorbers for multijunction photovoltaic applications because of their remarkable bandgap tunability, achieved through compositional mixing on the halide site. However, poor energy‐level alignment at the interface between wide‐bandgap mixed‐halide perovskites and charge‐extraction layers still causes significant losses in solar‐cell performance. Here, the origin of such losses is investigated, focusing on the energy‐level misalignment between the valence band maximum and the highest occupied molecular orbital (HOMO) for a commonly employed combination, FA0.83Cs0.17Pb(I1‐xBrx)3 with bromide content x ranging from 0 to 1, and poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] (PTAA). A combination of time‐resolved photoluminescence spectroscopy and numerical modeling of charge‐carrier dynamics reveals that open‐circuit voltage (VOC) losses associated with a rising energy‐level misalignment derive from increasing accumulation of holes in the HOMO of PTAA, which then subsequently recombine non‐radiatively across the interface via interfacial defects. Simulations assuming an ideal choice of hole‐transport material to pair with FA0.83Cs0.17Pb(I1‐xBrx)3 show that such VOC losses originating from energy‐level misalignment can be reduced by up to 70 mV. These findings highlight the urgent need for tailored charge‐extraction materials exhibiting improved energy‐level alignment with wide‐bandgap mixed‐halide perovskites to enable solar cells with improved power conversion efficiencies. [ABSTRACT FROM AUTHOR]

Semiconductor nanowires have inspired plenty of novel nanotechnology device concepts in photonics, electronics, and sensing, owing to their unique functionalities and integrability in heterogeneous platforms. Lattice‐mismatched core/shell heterostructures, in particular, open new avenues for strain engineering and material properties modification. A notable case is the widely tunable tensile strain in the core of GaAs/InxAl1‐xAs core/shell nanowires, which can be used to tailor the GaAs bandgap for applications across near‐infrared, like optical fiber telecommunication, imaging, photovoltaics, etc. As it is shown here, though, the bandgap narrowing under high tensile strain in the GaAs core is accompanied by fast non‐radiative recombination, which is undesirable for any device application. The limiting role of the lattice‐mismatched core/shell interface is revealed, and a novel core/dual‐shell heterostructure that employs an intermediate AlyGa1‐yAs shell (spacer) is proposed. This spacer decouples the GaAs/AlyGa1‐yAs interface, which confines electrons and holes into GaAs, from the lattice‐mismatched AlyGa1‐yAs/InxAl1‐xAs one, whereas the strain in GaAs is unaffected. Choosing the optimal spacer thickness, the photoluminescence yield increases significantly, with longer emission decay lifetimes and slower carrier cooling rates. Besides unlocking the potential of GaAs for photonic applications across near‐infrared, the proposed heterostructure concept can also be adopted for other material systems. [ABSTRACT FROM AUTHOR]

Blue gallium nitride (GaN) light‐emitting diodes (LEDs), combined with red/green fluorescent converters, have broad potential for display applications. Metal halide perovskites now show excellent luminescence properties and may be suitable as light converters. Here a simple solution‐processed method is reported to prepare a methylammonium lead bromide (MAPbBr3) nanoporous GaN composite. Fast (within 2 ps) energy transfer is demonstrated from photoexcited nanoporous GaN to encapsulate MAPbBr3 nanocrystals, as observed by transient absorption spectroscopy. The spatial confinement of the perovskite within the nanoporous GaN is shown to increase the perovskite radiative recombination rate. These results offer guidelines for developing high‐performance perovskite/nanoporous GaN optoelectronics. [ABSTRACT FROM AUTHOR]

The photoelectrochemical reduction of nitrate to ammonia (PEC NO3RR) has emerged as a promising pathway for facilitating the natural nitrogen cycle. The PEC NO3RR can lower the reduction potential needed for ammonia synthesis through photogenerated voltage, showcasing the significant potential for merging abundant solar energy with sustainable nitrogen fixation. However, it is influenced by the selective photocathodes with poor carrier kinetics, low catalytic selectivity, and ammonia yields. There are few reports on suitable photoelectrodes owning efficient charge transport on PEC NO3RR at low overpotentials. Herein, we rationally constructed the CuSn alloy co‐catalysts on the antimony sulfides with a highly selective PEC ammonia and an ultra‐low onset potential (0.62 VRHE). CuSn/TiO2/Sb2S3 photoelectrodes achieved an ammonia faradic efficiency of 97.82 % at a low applied potential of 0.4 VRHE, and an ammonia yield of 16.96 μmol h−1 cm−2 at 0 VRHE under one sun illumination. Dynamics experiments and theoretical calculations have demonstrated that CuSn/TiO2/Sb2S3 has an enhanced charge separation and transfer efficiency, facilitating photogenerated electrons to participate in PEC NO3RR quickly. Meanwhile, moderate NO2* adsorption on this photocathode optimizes the catalytic activity and increases the NH4+ yield. This work opens an avenue for designing sulfide‐based photocathodes for the efficient route of solar‐to‐ammonia conversion. [ABSTRACT FROM AUTHOR]

Highlights : A unique approach is proposed: constructing a polymer fiber rigid network with high glass transition temperature. Frozen bulk heterojunction morphology impeded deterioration of exciton quenching, charge transport, and charge extraction properties during thermal aging. The strategy is universal and can be further optimized for enhanced thermal stability and improved mechanical resilience. Organic photovoltaics (OPVs) need to overcome limitations such as insufficient thermal stability to be commercialized. The reported approaches to improve stability either rely on the development of new materials or on tailoring the donor/acceptor morphology, however, exhibiting limited applicability. Therefore, it is timely to develop an easy method to enhance thermal stability without having to develop new donor/acceptor materials or donor–acceptor compatibilizers, or by introducing another third component. Herein, a unique approach is presented, based on constructing a polymer fiber rigid network with a high glass transition temperature (Tg) to impede the movement of acceptor and donor molecules, to immobilize the active layer morphology, and thereby to improve thermal stability. A high-Tg one-dimensional aramid nanofiber (ANF) is utilized for network construction. Inverted OPVs with ANF network yield superior thermal stability compared to the ANF-free counterpart. The ANF network-incorporated active layer demonstrates significantly more stable morphology than the ANF-free counterpart, thereby leaving fundamental processes such as charge separation, transport, and collection, determining the device efficiency, largely unaltered. This strategy is also successfully applied to other photovoltaic systems. The strategy of incorporating a polymer fiber rigid network with high Tg offers a distinct perspective addressing the challenge of thermal instability with simplicity and universality. [ABSTRACT FROM AUTHOR]

A power conversion efficiency (PCE) exceeding 25% is achievable using perovskite solar cells (PSCs), with compositional engineering as the most effective strategy for high‐efficiency PSCs. However, the understanding of structural properties, charge‐carrier dynamics, and photoelectric properties, crucial for solar cell performance, still remains insufficient to establish a correlation with device performance for improving the PCE and stability of PSCs. This study uncovers the crucial links between structural disorder, charge‐carrier dynamics, and photoelectric properties of mixed‐perovskite (FAPbI3)1‐x(MAPbBr3)x thin films by investigating device performance for different mol%. Structural and morphological analyses reveal that the mixed perovskite‐thin‐film disorder exhibits composition dependence in the form of a checkmark trend, with a minimum near 0.8 mol%. Time‐resolved transient absorption spectroscopy demonstrates that charge‐carrier dynamics and optoelectronic properties exhibit a corresponding dependence on disorder. As the disorder of the perovskite thin film decreases, the trap density decreases, charge‐carrier loss decreases during the thermalization process, and the carrier lifetime is prolonged. Optical pump‐THz probe measurements show 20% effective mobility and a diffusion length of 34%. The device performance shows composition dependence and superior PCE is achieved at 0.8 mol%. This study highlights the significance of charge‐carrier dynamics in optimizing mixed perovskite composition for enhanced PCE and stability of PSCs. [ABSTRACT FROM AUTHOR]

The main obstacles to promoting the commercialization of perovskite solar cells (PSCs) include their record power conversion efficiency (PCE), which still remains below the Shockley–Queisser limit, and poor long‐term stability, attributable to crystallographic defects in perovskite films and open‐circuit voltage (Voc) loss in devices. In this study, potassium (4‐tert‐butoxycarbonylpiperazin‐1‐yl) methyl trifluoroborate (PTFBK) was employed as a multifunctional additive to target and modulate bulk perovskite defects and carrier dynamics of PSCs. Apart from simultaneously passivating anionic and cationic defects, PTFBK could also optimize the energy‐level alignment of devices and weaken the interaction between carriers and longitudinal optical phonons, resulting in a carrier lifetime of greater than 3 μs. Furthermore, it inhibited non‐radiative recombination and improved the crystallization capacity in the target perovskite film. Hence, the target rigid and flexible p‐i‐n PSCs yielded champion PCEs of 24.99 % and 23.48 %, respectively. More importantly, due to hydrogen bonding between formamidinium and fluorine, the target devices exhibited remarkable thermal, humidity, and operational tracking at maximum power point stabilities. The reduced Young's modulus and residual stress in the perovskite layer also provided excellent bending stability for flexible target devices. [ABSTRACT FROM AUTHOR]

The main obstacles to promoting the commercialization of perovskite solar cells (PSCs) include their record power conversion efficiency (PCE), which still remains below the Shockley–Queisser limit, and poor long‐term stability, attributable to crystallographic defects in perovskite films and open‐circuit voltage (Voc) loss in devices. In this study, potassium (4‐tert‐butoxycarbonylpiperazin‐1‐yl) methyl trifluoroborate (PTFBK) was employed as a multifunctional additive to target and modulate bulk perovskite defects and carrier dynamics of PSCs. Apart from simultaneously passivating anionic and cationic defects, PTFBK could also optimize the energy‐level alignment of devices and weaken the interaction between carriers and longitudinal optical phonons, resulting in a carrier lifetime of greater than 3 μs. Furthermore, it inhibited non‐radiative recombination and improved the crystallization capacity in the target perovskite film. Hence, the target rigid and flexible p‐i‐n PSCs yielded champion PCEs of 24.99 % and 23.48 %, respectively. More importantly, due to hydrogen bonding between formamidinium and fluorine, the target devices exhibited remarkable thermal, humidity, and operational tracking at maximum power point stabilities. The reduced Young's modulus and residual stress in the perovskite layer also provided excellent bending stability for flexible target devices. [ABSTRACT FROM AUTHOR]

State‐of‐the‐art triple cation, mixed halide perovskites are extensively studied in perovskite solar cells, showing very promising performance and stability. However, an in‐depth fundamental understanding of how the phase behavior in Cs0.05FA0.85MA0.10Pb(I0.97Br0.03)3 (CsMAFA) affects the optoelectronic properties is still lacking. The refined unit cell parameters a and c in combination with the thermal expansion coefficients derived from X‐ray diffraction patterns reveal that CsMAFA undergoes an α–β phase transition at ≈280 K and another transition to the γ‐phase at ≈180 K. From the analyses of the electrodeless microwave photoconductivity measurements it is shown that shallow traps only in the γ‐phase negatively affect the charge carrier dynamics. Most importantly, CsMAFA exhibits the lowest amount of microstrain in the β‐phase at around 240 K, corresponding to the lowest amount of trap density, which translates into the longest charge carrier diffusion length for electrons and holes. Below 200 K a considerable increase in deep trap states is found most likely related to the temperature‐induced compressive microstrain leading to a huge imbalance in charge carrier diffusion lengths between electrons and holes. This work provides valuable insight into how temperature‐dependent changes in structure affect the charge carrier dynamics in FA‐rich perovskites. [ABSTRACT FROM AUTHOR]

Understanding electron and ion dynamics is an important task for improving modern energy materials, such as photovoltaic perovskites. These materials usually have delicate nano‐ and microstructures that influence the device parameters. To resolve detailed structure–function relationships on the relevant micro‐ and nanometer length scales, the current macroscopic and microscopic measurement techniques are often not sufficient. Here, nanoscale surface photovoltage spectroscopy (nano‐SPV) and nanoscale ideality factor mapping (nano‐IFM) via time‐resolved Kelvin probe force microscopy are introduced. These methods can map nanoscale variations in charge carrier recombination, ion migration, and defects. To show the potential of nano‐SPV and nano‐IFM, these methods are applied to perovskite samples with different morphologies. The results clearly show an improved uniformity of the SPV and SPV decay distribution within the perovskite films upon passivation and increasing the grain size. Nevertheless, nano‐SPV and nano‐IFM can still detect local variations in the defect density on these optimized samples, guiding the way for further optimization. [ABSTRACT FROM AUTHOR]

Recently, multijunction tandem solar cells (TSCs) have presented high power conversion efficiency and revealed their immense potential in photovoltaic evolution. It is demonstrated that multiple light absorbers with various bandgap energies overcome the Shockley–Queisser limit of single‐junction solar cells by absorbing the wide‐range wavelength photons. Here, the main key challenges are reviewed, especially the charge carrier dynamics in perovskite‐based 2‐terminal (2‐T) TSCs in terms of current matching, and how to manage these issues from a vantage point of characterization. To do this, the effect of recombination layers, optical and fabrication hurdles, and the impact of wide bandgap perovskite solar cells are discussed extensively. Afterward, this review focuses on various optoelectronics, spectroscopic, and theoretical (optical simulation) characterizations to figure out those issues, especially current‐matching issues faced by the photovoltaic society. This review comprehensively provides deep insights into the relationship between the current‐matching problems and the photovoltaic performance of TSCs through a variety of perspectives. Consequently, it is believed that this review is essential to address the main problems of 2‐T TSCs, and the suggestions to elucidate the charge carrier dynamics and its characterization may pave the way to overcome such obstacles to further improve the development of 2‐T TSCs in relation to the current‐matching problems. [ABSTRACT FROM AUTHOR]

Organic solar cell (OSC) development continues to demonstrate impressive device efficiency improvements. However, the materials synthetic simplicity essential to industrialization remains seriously lacking attention, imparting inferior performance records in low‐cost devices. Hence, low bandgap and completely non‐fused electron acceptors (CNFEAs) having simple molecular structures are investigated herein. In contrast to typically explored fused‐ring acceptors with smaller backbone conformational variations, minimizing the interface recombination sites through a greater extent of localized domains is identified as more critical in CNFEAs, leading to remarkable fill factors (FFs) approaching 75%, among the highest currently realized for low‐cost systems. However, this comes with diminishing charge generation efficiency. The general ternary blend optimization strategy modifying the morphology of host components is limited in preserving such remarkably high FFs. To suppress the trade‐off while keeping notable FFs, a new perspective of constructing functionally bridged components based on optical, electronic, and thermodynamic properties is introduced here. Specifically, charge generation is unrestrained from the host acceptor localized domains through the introduction of a "bridge" component while also taking advantage of the configuration to channel polarons toward the efficient transport moieties of the host components. Accordingly, this work incubates understanding‐guided optimizations toward the advancement of more practical devices. [ABSTRACT FROM AUTHOR]

With near unity quantum efficiency and operational stability surpassing 250 days in outdoor conditions, aluminum‐doped SrTiO3 (Al:SrTiO3) with tailored cocatalysts is one of the promising photocatalysts for scalable solar H2 production. Nevertheless, mechanistic insights behind Al‐doping and Rh cocatalyst‐induced enhanced overall water splitting (OWS) efficiency are not well elucidated. Herein, detailed charge carrier dynamics from sub‐picosecond to milliseconds are unveiled for Al:SrTiO3 by transient (optical and microwave probe) spectroscopy measurements. The obtained transients are rationalized using a theoretical model considering bimolecular recombination, trapping and detrapping processes. Due to a decrease in an n‐type doping density, Al doping of SrTiO3 significantly prolongs bulk carrier lifetime from 50 ns to 12.5 µs (consistent with the previous report). The crucial electron extraction process by the Rh cocatalyst located on the surface from Al:SrTiO3 occurs well before the decay of charge carriers. In contrast, µs‐long electron extraction time observed in SrTiO3 is significantly slower than tens of ns bulk carrier lifetime, thus reducing the photocatalytic OWS reaction. Complementary analysis in conjunction with in situ charge carrier dynamics in water interface addresses the mechanistic insight into Al‐doping‐induced enhancement of OWS activity. Correlating material properties, carrier dynamics and photocatalytic activity is expected to help design next‐generation photocatalysts via dopant and/or defects engineering for efficient solar‐fuel production. [ABSTRACT FROM AUTHOR]

In this study, we present a comprehensive investigation into the charge generation mechanism in bulk-heterojunction organic solar cells employing non-fullerene acceptors (NFAs) both with and without the presence of processing additives. While photovoltaic devices based on Y6 or BTP-eC9 have shown remarkable power conversion efficiencies, the underlying charge generation mechanism in polymer:NFA blends remains poorly understood. To shed light on this, we employ transient absorption (TA) spectroscopy to elucidate the charge transfer pathway within a blend of the donor polymer PM6 and NFAs. Interestingly, the charge carrier lifetimes of neat Y6 and BTP-eC9 are comparable, both reaching up to 20 ns. However, the PM6:BTP-eC9 blend exhibits substantially higher charge carrier generation and a longer carrier lifetime compared to PM6:Y6 blend films, leading to superior performance. By comparing TA data obtained from PM6:Y6 or PM6:BTP-eC9 blend films with and without processing additives, we observe significantly enhanced charge carrier generation and prolonged charge carrier lifetimes in the presence of these additives. These findings underscore the potential of manipulating excited species as a promising avenue for further enhancing the performance of organic solar cells. Moreover, this understanding contributes to the advancement of NFA-based systems and the optimization of charge transfer processes in polymer:NFA blends. [ABSTRACT FROM AUTHOR]

The quality of the perovskite absorption layer is critical for the high efficiency and long‐term stability of perovskite solar cells (PSCs). The inhomogeneity due to local lattice mismatch causes severe residual strain in low‐quality perovskite films, which greatly limits the availability of high‐performance PSCs. In this study, a multi‐active‐site potassium salt, pemirolast potassium (PP), is added to perovskite films to improve carrier dynamics and release residual stress. X‐ray photoelectron spectroscopy (XPS) and Fourier‐transform infrared spectroscopy (FTIR) measurements suggest that the proposed multifunctional additive bonds with uncoordinated Pb2+ through the carbonyl group/tetrazole N and passivated I atom defects. Moreover, the residual stress release is effective from the surface to the entire perovskite layer, and carrier extraction/transport is promoted in PP‐modified perovskite films. As a result, a champion power conversion efficiency (PCE) of 23.06% with an ultra‐high fill factor (FF) of 84.36% is achieved in the PP‐modified device, which ranks among the best in formamidinium‐cesium (FACs) PSCs. In addition, the PP‐modified device exhibits excellent thermal stability due to the inhibited phase separation. This work provides a reliable way to improve the efficiency and stability of PSCs by releasing residual stress in perovskite films through additive engineering. [ABSTRACT FROM AUTHOR]

The use of colloidal nanocrystals as part of artificial photosynthetic systems has recently gained significant attention, owing to their strong light absorption and highly reproducible, tunable electronic and optical properties. The complete photocatalytic conversion of water to its components is yet to be achieved in a practically suitable and commercially viable manner. To complete this challenging task, we are required to fully understand the mechanistic aspects of the underlying light-driven processes involving not just single charge carriers but also multiple charge carriers in detail. This review focuses on recent progress in understanding charge carrier dynamics in semiconductor nanocrystals and the influence of various parameters such as dimension, composition, and cocatalysts. Transient absorption spectroscopic studies involving single and multiple charge carriers, and the challenges associated with the need for accumulation of multiple charge carriers to drive the targeted chemical reactions, are discussed. [ABSTRACT FROM AUTHOR]

Recent advances in the growth of III-V semiconductor nanowires (NWs) hold great promise for nanoscale optoelectronic device applications. It is established that a small amount of nitrogen (N) incorporation in III-V semiconductor NWs can effectively red-shift their wavelength of operation and tailor their electronic properties for specific applications. However, understanding the impact of N incorporation on non-equilibrium charge carrier dynamics and transport in semiconducting NWs is critical in achieving efficient semiconducting NW devices. In this work, ultrafast optical pump-terahertz probe spectroscopy has been used to study non-equilibrium carrier dynamics and transport in Te-doped GaAsSb and dilute nitride GaAsSbN NWs, with the goal of correlating these results with electrical characterization of their equilibrium photo-response under bias and low-frequency noise characteristics. Nitrogen incorporation in GaAsSb NWs led to a significant increase in the carrier scattering rate, resulting in a severe reduction in carrier mobility. Carrier recombination lifetimes of 33 ± 1 picoseconds (ps) and 147 ± 3 ps in GaAsSbN and GaAsSb NWs, respectively, were measured. The reduction in the carrier lifetime and photoinduced optical conductivities are due to the presence of N-induced defects, leading to deterioration in the electrical and optical characteristics of dilute nitride NWs relative to the non-nitride NWs. Finally, we observed a very fast rise time of ∼2 ps for both NW materials, directly impacting their potential use as high-speed photodetectors. [ABSTRACT FROM AUTHOR]

Summary: A novel Bi2WO6/rGO/3D‐GCN composite with 2D/2D/3D heterojunction is synthesized by a simple microwave‐assisted method and used as a visible‐light‐responsive photocatalyst in the CO2 reduction. The chemical properties and morphology of prepared photocatalysts are identified by a variety of analytic tools and spectroscopies. As a result, the heterojuncted Bi2WO6/3D‐GCN exhibits superior CO2 reduction performance as compared to the pristine 3D‐GCN, which may be caused by the intimate contact between Bi2WO6 and 3D‐GCN. The harvest of visible‐light absorption, reduced charge transfer resistance and suppressed recombination of electron‐hole pairs are accountable for surpassing performance of Bi2WO6/3D‐GCN. Upon further incorporation of rGO into Bi2WO6/3D‐GCN heterojunction, the photocatalytic production of CO can be notably boosted by ca. 7.9‐fold higher than 3D‐GCN, suggesting the key contribution of rGO in facilitating the interfacial charge transfer kinetics and increasing CO2 uptake. This work exemplifies a time and energy‐saving method to prepare the unique 3D GCN with laminated hexagonal structure which can serve as a shuttle for Bi2WO6 heterojunction and rGO incorporation. This Bi2WO6/rGO/3D‐GCN photocatalyst could offer the potential applications in the natural solar conversions of CO2. [ABSTRACT FROM AUTHOR]

Metal halide perovskites having high defect tolerance, high absorption characteristics, and high carrier mobility demonstrate great promise as potential light harvesters in photovoltaics and optoelectronics and have experienced an unprecedented development since their occurrence in 2009. Semiconductor quantum dots (QDs), on the other hand, have also been proved to be very flexible toward shape, dimension, bandgap, and optical properties for constructing optoelectronic devices. Of late, a strategic combination of both materials has demonstrated extraordinary promise in photovoltaic applications and optoelectronic devices. Combining QDs and perovskites has proved to be quite an effective strategy toward the formation of pinhole‐free and more stable perovskite crystals along with tunability of other properties. To boost this exciting research field, it is imperative to summarize the work done so far in recent years to provide an intriguing insight. This review is a critical account of the advanced strategy toward combining these two fascinating materials, including their different synthetic approaches regarding heteroepitaxial growth of perovskite crystals on QDs, carrier dynamics at the interface and potential application in the field of solar cells, light emitting diodes, and photodetectors. [ABSTRACT FROM AUTHOR]

Monoclinic α‐Ag2S is an intriguing member of transition metal sulfides with great potential for all‐inorganic flexible optoelectronics and thermoelectrics. Fabrication of large‐area, high‐quality α‐Ag2S thin films and understanding their charge transport properties are critical for device operations yet have remained largely unexplored. Here, a novel two‐step, the solution‐processed approach is reported to produce wafer‐sized, highly crystalline α‐Ag2S thin films. Ultrafast terahertz (THz) conductivity measurements reveal that photogenerated charge carriers undergo efficient band transport, with room‐temperature mobility of ≈150 cm2 V‐1 s‐1 and a diffusion length exceeding 500 nm. Furthermore, introducing poly(vinyl alcohol) (PVA) as the rigid component into the aqueous silver thiolate precursor enables the synthesis of free‐standing α‐Ag2S thin films with a mobility of ≈35 cm2 V‐1 s‐1, demonstrating their potential for flexible optoelectronics. This study provides a facile synthesis route for high‐quality, large‐area α‐Ag2S thin films with good charge transport properties, relevant for their integration into optoelectronics and wearable electronics. [ABSTRACT FROM AUTHOR]

Sb2Se3 has emerged as an important photoelectrochemical (PEC) and photovoltaic (PV) material due to its rapid rise in photoconversion efficiencies. However, Sb2Se3 has a complex defect chemistry, which reduces the maximum photovoltage. Thus, it is important to understand these defects and develop defect passivation strategies in Sb2Se3. A comprehensive investigation of the charge carrier dynamics of Sb2Se3 and the influence of sulfur treatment on its optoelectronic properties is performed using time‐resolved microwave conductivity (TRMC), photoluminescence (PL) spectroscopy, and low‐frequency Raman spectroscopy (LFR). The key finding in this work is that upon sulfur treatment of Sb2Se3, the carrier lifetime is increased by the passivation of deep defects in Sb2Se3 in both the surface region and the bulk, which is evidenced by increased charge carrier lifetime of TRMC decay dynamics, increased radiative recombination efficiency, decreased deep defect level emission (PL), and the emergence of new vibration modes by LFR. [ABSTRACT FROM AUTHOR]

[Display omitted] • Potassium precursor choice significantly affects g-C 3 N 4 ′s photocatalytic behavior. • K precursors differently increase density of localised states and light harvesting. • Choice of precursor, not amount of K, crucially impacts CB/VB potentials in g-C 3 N 4. • KCl precursor significantly enhanced surface ability of g-C 3 N 4 to form ·OH radicals. • TCSPC revealed higher average carrier lifetime in KCl-based g-C 3 N 4 compared to KOH. The previous studies on K-doped g-C 3 N 4 suggest a simple correlation between the increased potassium content and the improved photocatalytic activity due to a shift of the valence band potential to more positive values, leading to the direct oxidation of hydroxyl ions to hydroxyl radicals by holes. In this study, we investigated the influence of different potassium precursors on the properties and photocatalytic efficiency of K-modified g-C 3 N 4 materials in Rhodamine B degradation. Detailed characterization revealed that the choice of precursor significantly affects the structural and optoelectronic properties with complex correlations rather than superficial relationships between potassium content and photocatalytic activity. Notably, KCl-based samples, despite having a lower specific surface area, exhibited enhanced photocatalytic properties due to prolonged carrier lifetimes and improved charge transfer efficiency compared to KOH-based samples. Higher precursor concentrations resulted in more recombination centers, increasing Urbach energy and reducing photocatalytic activity. These findings underscore the importance of precise synthesis control, revealing that both K and Cl atoms act as charge transfer bridges, improving the material's photocatalytic properties beyond mere surface area enhancement. In addition, even smaller amounts of Cl atoms in g-C 3 N 4 showed much higher impact on the final position of conduction and valence band potentials than K atoms. [ABSTRACT FROM AUTHOR]

"Necessity is the mother of invention." The global imperative to transition from fossil fuels to renewable energy sources, driven by the pressing issue of climate change, highlights the significance of advancing solar energy technologies. While single junction solar cells have reached a peak efficiency of approximately 31 %, the pursuit of higher efficiency has led to the exploration of tandem solar cell architectures, including perovskite-silicon and all-perovskite configurations. However, the widespread use of lead in perovskite structures raises environmental and health concerns. In response to these challenges, this study proposes a novel approach by integrating a tin-based wide bandgap absorber layer with a silicon HIT solar cell (Heterojunction with Intrinsic Layer). The investigation consists of an extensive exploration of six different carrier transport layers (CTL) for the top perovskite layer, considering variations in thickness and defect density. A comprehensive analysis of charge carrier dynamics within the device is conducted to understand the role of defect density in influencing solar cell performance parameters. Simulation results show that the overall tandem device gives an encouraging PCE of 32.12 % in 2 T configuration due to its excellent high value of current density matching 17.63 mA/cm2 and open-circuit voltage of 2.19V. We sincerely hope that our work will open new avenues in the field of Solar Photovoltaics paving the way for future innovations. [Display omitted] Significance of the work. • Detailed study and understanding of the role of lead free perovskite absorber layers with Industrial solar cell. • Utilizing a tin-based absorber layer with a bandgap of 1.61eV, in tandem configuration with a silicon HIT solar cell (Heterojunction with intrinsic layer) having a bandgap of 1.12eV. • The overall tandem device gives an encouraging PCE of 32.12 % in 2 T configuration due to its excellent high value of current density matching. • The experimental validation of simulation study with previously published data is critical. [ABSTRACT FROM AUTHOR]

Recent advances in photovoltaic devices demonstrate a potential candidature of the lead halide perovskite solar cells (PSCs) to fulfill the all-electric future of the world. Further improvements in efficiency and stability require minimization of non-radiative recombination arising due to the tr ap states created by the vacancies and defects. The device’s performance is mostly determined by the perovskite absorber material, which has single-cation, mixed-cation, and/or mixed-halide composition-dependent optoelectronic capabilities. Herein, we present an insight on the state of the art of PSCs, including types of defects, their effects, and remedies of the same. Various design strategies administered to grow highly crystalline perovskite films with low defects at interfaces are described in detail. The inclusion of a few nm thin interlayer between perovskite and charge transport layer (CTL) is an effective way to passivate the defect at the interface. Furthermore, additive engineering is emerging as an excellent strategy to grow the defect-free perovskite by simply adding a polymer, ionic liquids, organic/inorganic salts in precursor solution without precipitating after film formation. The mitigation of charge recombination could be achieved by efficient charge extraction through proper energy alignment of CTLs and absorbers. Notably, we emphasize the interface, additive, and gradient band alignment engineering and resulting improvement in the photocurrent density, photovoltage, power conversion efficiency, and long-term stability. The present review gives complete information about PSCs, starting from the selection of the materials to PSC fabrication, charge carrier dynamics, defects, effects, and remedies. We hope that this summarised information will give a basic understanding of designing new passivation strategies for advancing PSC’s present state of the art. [ABSTRACT FROM AUTHOR]

Constructing favorable heterointerface to facilitate photogenerated carrier transport is an effective way to improve the photocatalytic activities of semiconductor catalysts. However, the fabrication of atomic-level interface remains a challenge due to the difficulties in constructing intimate interface contact. Herein, a unique atom-to-atom TiO 2 /ZrTiO 4 heterointerface with the potential formation of Ti–O–Ti(Zr) bonds between TiO 2 and ZrTiO 4 was constructed through the in-situ formation of the two components using a one-step sol-gel method. The resulting photocatalyst exhibited superior photocatalytic activity and high stability, i.e., about 97% of Rhodamine B was degraded after visible light irradiation for 90 min for three consecutive photodegradation cycles. By further analyses such as refined X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS), Raman microscope (Raman), photoluminescence (PL), and photoelectrochemical spectra (TP and EIS), it revealed that the atom-to-atom heterointerface of TiO 2 /ZrTiO 4 with stronger interaction forces would greatly accelerate the charge separation as well as provide generous defect sites, boosting the number of photogenerated carriers available at reaction sites, thus contribute to the improvement of photocatalytic performance. The present work demonstrates a new approach of in-situ construction for interface engineering TiO 2 based catalyst, providing design guidelines for heterointerface photocatalytic structures. [ABSTRACT FROM AUTHOR]

Environmental pollution and shortage of energy resources are considered as the most serious threats faced by mankind. Heterogeneous photocatalysis has become one of the most frequently investigated technologies, thanks to its dual ability to convert solar energy into chemical energy and to perform environmental remediation. However, the low quantum efficiencies achieved so far with TiO 2 photocatalysts represent a big challenge that needs to be overcome before their potential can be fully realized. Among other possibilities, the loading of noble metals (e.g. platinum) is a proven strategy to enhance the TiO 2 photoactivity. However, the method by which Pt/TiO 2 is prepared appears to play a crucial role in tuning the photocatalytic activity. In this work, platinum-loaded anatase TiO 2 photocatalysts were prepared using two alternative methods: photodeposition by reduction of PtCl 62- and physical mixing of TiO 2 with Pt nanoparticles synthesized by laser ablation. The effect of the Pt deposition method was evaluated for the photoreforming reaction of two organic substrates: naphthalene, and methanol. To explain the different activities, a full physicochemical characterization was performed for these samples. Moreover, the charge carrier dynamics in pristine and platinized TiO 2 were investigated by transient absorption spectroscopy (TAS), and by the electron paramagnetic resonance (EPR) technique, respectively. The photodeposition of Pt caused a significant decrease in the charge carrier recombination rates, which in turn led to an increased rate of the photocatalytic reactions. This effect was mainly attributed to the strong metal-semiconductor interaction resulting from the photodeposition process, aided by the preferential deposition on crystalline facets with stronger reducing properties. [Display omitted] • Different loading methods result in different photocatalytic activities. • The stronger the metal-semiconductor interaction, the better the e − − h + separation. • Platinization method affects the charge carrier dynamic as revealed by EPR and TAS. • The chemical nature of the hole scavenger governed the photocatalytic efficiency. • The stronger the Pt-TiO 2 interaction, the more efficient the charge carrier separation. [ABSTRACT FROM AUTHOR]

As emerging eco‐friendly alternatives to traditional Cd/Pb‐based quantum dots (QDs), InP/ZnSe(S) core/shell QDs have demonstrated huge potential in light‐emitting technologies. So far, these QDs have been rarely employed in solar energy conversion applications due to their type‐I band structure offering limited photo‐induced charge carrier separation and transfer. Here, a controllable Cu shell doping approach is reported to engineer the optoelectronic properties of InP/ZnSe core/shell QDs and realize high performance and stable solar‐driven photoelectrochemical (PEC) hydrogen evolution. As compared to the pristine InP/ZnSe QDs, the Cu‐doped core/shell QDs exhibit enhances the photo‐induced electron transfer rate due to the capture of photo‐generated holes via Cu impurity states in the shell, leading to improved photocurrent density and long‐term durability in as‐fabricated InP/ZnSe:Cu QDs‐PEC devices under standard one sun illumination. The results indicate that the doping of Cu in the shell has a preeminent effect on the optoelectronic properties of the core/shell QDs and may open up new avenues to tailor eco‐friendly core/shell QDs for high performance and stable solar energy conversion. [ABSTRACT FROM AUTHOR]

This work majorly aims to synthesize and also investigate the structural, optical, magnetic and optical features of ZrO 2 /ZnFe 2 O 4 nanocomposite. Here, different ratios of novel hetero-junction ZrO 2 /ZnFe 2 O 4 were synthesized by simple and fast solution combustion route. The X-ray diffraction results showed the formation of ZrO 2 and ZnFe 2 O 4 nanoparticles and ZrO 2 /ZnFe 2 O 4 nanocomposites without any impurity. The formation of hetero-junction effectively inhibits the photo-generated charge carrier recombination. The degradation of Indigo Carmine dye by ZrO 2 /ZnFe 2 O 4 photocatalyst was achieved through synergistic effects with 98% degradation and removal of 77% COD from the industrial dye waste water under Sunlight irradiation. Mixing of ferrites with zirconia greatly improves the photocatalytic activity that has been clearly proposed with the help of mechanism. ZZFO 12 NC exhibits better photocatalytic activity due to the combined facets of photo and Fenton activity. The exposure and enhancement of fingerprints in various surfaces are achieved by a modest, extremely sensitive and eco-friendly method. ZZFO12 NC offer great potential as an active photocatalyst for degradation of 54% of organic pollutant present in industrial waste water under natural Sunlight. [ABSTRACT FROM AUTHOR]

The article titled "Nanoscale Surface Photovoltage Spectroscopy" in Advanced Optical Materials discusses the use of Scanning Probe Microscopy to measure the nanoscale photoresponse of perovskite solar cell surfaces. The method, called nanoscale surface photovoltage spectroscopy (nano-SPV), allows for the resolution and mapping of different areas with varying defect density in correlation with the sample topography. The authors' findings highlight the influence of passivation and grain size changes on defects, contributing to a better understanding of defects in perovskite materials. The authors of the article are Yenal Yalcinkaya, Pascal N. Rohrbeck, Emilia R. Schütz, Azhar Fakharuddin, Lukas Schmidt‐Mende, and Stefan A.L. Weber. [Extracted from the article]

• Advanced electrochemical techniques employed to track charge dynamics. • In-situ modifications can improve the charge carrier kinetics. • Ta+5 simultaneously dopes and segregates at hematite crystal surfaces. • Na+ changes hematite morphology but it has limited impact in the carrier kinetics. • Zn+2 hinders charge separation and increases bulk recombination. This letter focuses on monitoring alterations in the charge carrier dynamics associated with in-situ modifications into hematite photoanodes, employing advanced electrochemical techniques. A simple and scalable polymeric precursor solution, deposited by spin-coating, was employed to synthesize hematite based photoanodes. Among various modifications, Tantalum (Ta+5) shows the most promising results, yielding a hydrogen production rate of 24.0 μmol cm−2h−1 at 1.23V RHE. This is attributed to Ta5+ segregation at hematite grain surface, which facilitates the charge transport efficiency and leads to higher external quantum efficiency. Conversely, sodium (Na+) primarily increases the film thickness with limited observable effects on charge carrier dynamics, while zinc (Zn+2) adversely affects hematite performance due to its negative effect on charge separation efficiency and increased bulk recombination. [ABSTRACT FROM AUTHOR]

The article focuses on charge carrier dynamics in perovskite-based tandem solar cells, using advanced spectroscopy and simulations to address challenges like defect density, bandgap tuning, and achieving accurate current matching for improved performance.

CsPbBr3 nanocrystals (NCs) encapsulated in a transparent polystyrene (PS) fiber matrix (CsPbBr3@PS) have been synthesized to protect the NCs. The ultrafast charge delocalization dynamics of the embedded NCs have been demonstrated, and the results are compared with the pristine CsPbBr3 in toluene. The electrospinning method was employed for the preparation of CsPbBr3@PS fibers by using a polystyrene solution doped with pre‐synthesized CsPbBr3 and characterized by XRD, HRTEM, and X‐ray photoelectron spectroscopy (XPS). Energy level diagrams of CsPbBr3 and PS suggest that CsPbBr3@PS fibers make a type I core–shell structure. The carrier cooling for CsPbBr3@PS fibers is found to be much slower than pure CsPbBr3 NCs. This observation suggests that photoexcited electrons from CsPbBr3 NCs get delocalized from the conduction band of the perovskite to lowest unoccupied molecular orbital (LUMO) of the PS fiber matrix. The CsPbBr3@PS fibers possess remarkable stability under ambient conditions as well as in water over months. The clear understanding of charge carrier relaxation dynamics of CsPbBr3 confined in PS fibers could help to design robust optoelectronic devices. [ABSTRACT FROM AUTHOR]

The charge carrier dynamics of epitaxial hematite films is studied by time‐resolved microwave (TRMC) and time‐resolved terahertz conductivity (TRTC). After excitation with above bandgap illumination, the TRTC signal decays within 3 ps, consistent with previous reports of charge carrier localization times in hematite. The TRMC measurements probe charge carrier dynamics at longer timescales, exhibiting biexponential decay with characteristic time constants of ≈20–50 ns and 1–2 μs. From the change in photoconductance, the effective carrier mobility is extracted, defined as the product of the charge carrier mobility and photogeneration yield, of differently doped (undoped, Ti, Sn, Zn) hematite films for excitation wavelengths of 355 and 532 nm. It is shown that, unlike in conventional semiconductors, donor doping of hematite dramatically increases the effective mobility of the photogenerated carriers. Furthermore, it is shown that all hematite films possess higher effective mobility for 355 nm excitation than for 532 nm excitation, although the time dependence of the photoconductance decay, or charge carrier lifetime, remains the same. These results provide an explanation for the wavelength dependent photoelectrochemical behavior of hematite photoelectrodes and suggest that an increase in photogeneration yield or charge carrier mobility is responsible for the improved performance at higher excitation energies. [ABSTRACT FROM AUTHOR]

[Display omitted] • BN nanosheets act as a barrier, inhibiting ion migration within perovskite layers. • BN also improved charge transport and carrier mobility. • Perovskite photodiodes incorporated with BN exhibit exceptional X-ray stability. Metal halide perovskites have been widely used in optoelectronic applications due to their excellent optoelectronic properties. However, ensuring their stability during operation remains a significant challenge. In this study, we investigated the charge carrier dynamics of perovskite films and devices, comparing those with and without the insertion of boron nitride on the grain boundaries. It was revealed that the charge transport and stability could be significantly enhanced with the present of boron nitride nanosheets on the grain boundaries. The incorporation of boron nitride led to a substantial improvement in charge carrier mobility and lifetime, without any noticeable changes in phase segregation or photostability. Moreover, the perovskite detectors incorporating boron nitride exhibited suppressed ion migration and dark current, while demonstrating an enhanced photoresponse and radiation exposure capability. These findings indicate that the addition of insulating boron nitride nanosheets acts as a stabilizer, enhancing the stability of both the perovskite thin films and the devices. Additionally, the incorporation of boron nitride significantly improved the device performance benefiting from the enhanced charge transport, indicating that the boron nitride nanosheets enhanced perovskite photodiodes possess great potential for X-ray detection and imaging. [ABSTRACT FROM AUTHOR]

Light-induced strategies are crucial for deciding the physical and chemical properties of organometal halide perovskite materials and their photovoltaic devices. Herein, the triple cation ((FA 0.83 MA 0.17) 0.95 Cs 0.05 Pb(I 0.83 Br 0.17) 3) hybrid perovskite films have been fabricated using a simple solution-processed method. These films were illuminated by blue light (417 nm) for different time durations and characterized for structural, surface morphological, optical, and charge carrier dynamics. Under illumination conditions, a reduction in lattice micro-strain has been observed. The enhanced optical absorbance and reduced non-radiative recombination have also been monitored in light-illuminated perovskite films. Further, time-resolved photoluminescence (TRPL) and ultra-fast transient absorption spectroscopy (TAS) measurements have been performed to study the charge carrier dynamics. TRPL results show that the average lifetime of charge carriers has increased from 3 ns to 19 ns upon continuous light illumination conditions. Further, the recombination time of the charge carriers decreased from 226 ps to 66 ps upon continuous light illumination for 30 min. This study suggests that light-induced experiments on perovskite films can be utilized for micro-strain regulation and modulation of their charge carrier dynamics for future perovskite solar cell applications. [Display omitted] • Regulation of micro-strain of (FA 0.83 MA 0.17) 0.95 Cs 0.05 Pb(I 0.83 Br 0.17) 3 hybrid perovskite films due to light illumination. • The enhanced optical absorbance and reduced non-radiative recombination have also been monitored in light-illuminated perovskite films. • Relaxation of hot charge carriers from the high excited states to quasi-thermal equilibrium states has been observed by transient absorption spectra. [ABSTRACT FROM AUTHOR]

• Analytic methods to study the charge carrier dynamics are introduced. • The fates of charge carrier trapping and recombination are understood. • Various interfacial charge transfer processes are discussed case-by-case. Heterogeneous photocatalysis mediated by semiconducting TiO 2 has attracted continuous interest during the past decades and has shown great potentials in environmental remediation and solar energy conversion. Basically, photocatalysis is initiated by the TiO 2 excitation. The generated charge carriers undergo trapping, recombination, and interfacial transfer before proceeding the redox reaction at TiO 2 surface. Monitoring the charge carrier dynamics is of particulate importance for understanding the underlying mechanism and designing efficient photocatalysts. This review overviews the recent progress in characterization of charge carrier dynamics. We will present the analytic techniques for monitoring the fate of charge carriers at each elementary photocatalytic step, including charge carrier generation, trapping and recombination inside the photocatalyst, as well as the interfacial charge transfer. The charge carrier dynamics at TiO 2 /H 2 O interface, hole transfer reactions for O 2 production, and photocatalytic oxidation of organic compounds and nitric oxides, and electron transfer reactions for photocatalytic reduction of viologens and metal ions are addressed, aiming at a deeper understanding of photocatalytic process. [ABSTRACT FROM AUTHOR]

Abstract Plasmonic metal-semiconductor hybrid mediated photocatalysis has perceived as a sustainable technology, because of the contribution from each component and to the multifaceted functionalities attained due to the synergistic intra-particle interactions at the interface of integrated components. Due to its intriguing structure-electronic properties, Au-ZnO are intensively investigated for the light induced pollutant degradation and hydrogen evolution under a variety of reaction conditions. The deposition of Au metallic islands induces the visible light response through surface plasmon resonance with concomitant enhancement in the charge carrier separation directly related to the heterojunction formation. In this focused review article, choice of Au over other noble metals, preparative method, band offsets between ZnO and Au, structural configuration of Au-ZnO, photoluminescence studies, morphology induced reactivity, charge carrier dynamics, and mechanisms of photocatalytic reactions associated with Au-ZnO are discussed. An overview of the Au deposition methods provides some insights into the pros and cons of the wide array of techniques used. The significance of molecular linkers in the functionalization of Au or ZnO surface towards achieving the stable composite are also explained. The effective role of Au NPs defining their size-shape-morphology on the ZnO surface together with SPR effects and optimum content in promoting the photocatalytic performance are emphasized. Further advancements in Au-ZnO accomplished by heterostructuring with metals, carbon materials and wide/narrow gap semiconductors are featured by concentrating on the preparation methods and charge carrier dynamics. This review contributes for the modulation of multifunctional Au-ZnO heterostructure concerning the photon harvesting ability, charge carrier separation, interface engineering, and structural stability with their direct implications in energy related fields. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ultra-thin alumina coatings are grown on the surface of bismuth vanadate photoanodes using atomic layer deposition. • These coatings favourably shift the onset potential for water oxidation by ∼200 mV and increase photocatalytic currents. • The simulated solar photocurrent increased from ∼0.47 mA cm−2 in uncoated BiVO 4 to ∼3.0 mA cm−2 in Al 2 O 3 -coated BiVO 4. • The charge carrier dynamics are studied for the first time using transient photocurrent and transient absorption spectroscopy. Abstract Bismuth vanadate (BiVO 4) has emerged as one of the most promising photoanode materials for oxidising water due to its visible light activity and low cost. Recent studies have shown that the performance of BiVO 4 photoanodes can be remarkably improved when coated with ultra-thin passivation layers. In this article we investigate the use of ultra-thin Al 2 O 3 layers grown using atomic layer deposition (ALD). At an optimum thickness (∼0.33 nm, 3 ALD cycles), the Al 2 O 3 layer favourably shifted the onset potential by ∼200 mV and increased photocatalytic currents for the water oxidation reaction. When held at 1.23 V RHE , we observe a remarkable increase in the theoretical solar photocurrent; from ∼0.47 mAcm−2 in uncoated BiVO 4 to ∼3.0 mAcm−2 in Al 2 O 3 -coated BiVO 4. Using transient photocurrent (TPC) and transient absorption spectroscopy (TAS) the charge carrier dynamics in Al 2 O 3 -coated BiVO 4 photoanodes were examined for the first time. TPC showed that photogenerated electrons in the BiVO 4 layer were extracted within ∼1 ms. TAS showed that the remaining holes oxidised water from ∼100 ms to 1 s. Ultra-thin Al 2 O 3 coatings did not improve the reaction kinetics towards water oxidation, but rather, suppressed bi-molecular recombination on the μs-ms timescale in BiVO 4 , and increased the yield of long-lived holes on the ms-s timescale required to oxidise water. This is attributed to an inhibition of surface recombination on BiVO 4 by Al 2 O 3 , which inhibited the early timescale recombination of charge carriers formed within the space charge layer. [ABSTRACT FROM AUTHOR]

We synthesized SiCN nanowires by a combination of high-energy ball milling and post-heat treatment using high-purity silicon and carbon nanopowders (<100 nm), and evaluated the effects of process parameters on their structural, chemical, optical properties, photoelectrocatalytic and photocatalytic activities. Cubic SiCN crystal phase with a lattice constant of 4.35 Å was observed. The optical bandgap of 2.20 eV was observed with nanowire diameters ranging from 23 nm to 37 nm. The SiCN nanowires showed good photocatalytic activity with the highest degradation percentage of ∼99% in 40 min for the degradation of Rhodamine B dye under visible light, and a degradation rate of 0.0841 min −1 . The SiCN nanowires showed no significant reduction in photocatalytic activity for five consecutive cycles, indicating that they are extremely stable against organic dyes. The SiCN nanowires were used for photoelectrochemical water splitting and the effect of electrolytes was studied. The highest photocurrent density of 5 × 10 -2 mAcm -2 vs. Ag/AgCl in 0.1 M KOH solution was achieved owing to the improved visible light collection and electron hole separation. The exchange current density, Tafel slopes, and limiting diffusion current density were found to be 3.17 mAcm -2 , 68.13 mVdec −1 , and 1.54 mAcm -2 , respectively. Further, the specific capacitance of the SiCN nanowires was estimated, obtained of 188 mFcm -2 at a current density of 5 mAcm -2 . [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Mixing BaSO 4 with TiO 2 improves the photocatalytic performance by scattering of UV light. • CaCO 3 revealed lead to a stabilization of trapped charge carriers on TiO 2. • Sodium ions reduced the activity of TiO 2 by fast charge recombination. Abstract Building materials employing TiO 2 as photocatalyst usually contain several additives. The interplay of the additives and the photocatalytic NO degradation has been rarely investigated, although it is of utmost importance for the design of new highly active materials. Hence, in the present study the effects of such additives (BaSO 4 , CaCO 3 , and Na 2 CO 3) on the photocatalytic activity and on the charge carrier dynamics have been evaluated. The degradation of nitric oxide (NO) was studied employing a standardized photocatalytic activity test (ISO 22197-1) and the charge carrier kinetics were observed by transient absorption spectroscopy. TiO 2 -additive powder samples were obtained by grinding pure anatase TiO 2 with a single additive with varying volume composition. Overall, the obtained apparent quantum yields of the samples correlated well with the charge carrier concentration. Moreover, BaSO 4 has proven its chemically inert character. However, the optical properties of the powder samples containing BaSO 4 lead to relatively high photonic efficiencies even with low TiO 2 content. TiO 2 -BaSO 4 samples with only 25% TiO 2 showed nearly the same quantum yield for the NO degradation as the pure photocatalyst. The reason for the high photocatalytic activity is the strong absorption of UV-light caused by the scattering inside the powder samples. The charge carrier kinetics of TiO 2 after the addition of Na 2 CO 3 and CaCO 3 revealed two different chemical effects of the additives. Na 2 CO 3 reduced the apparent quantum yield of the TiO 2 samples due to the fast recombination of charge carriers (identified by a fractal kinetics fit). On the other hand, the presence of CaCO 3 had a beneficial influence on the stabilization of trapped charge carriers in TiO 2. [ABSTRACT FROM AUTHOR]

The vertically oriented Ni (Ni 0 ) decorated hematite nanorod array have been synthesized. The optimal Ni loading enhances photocurrent density > 4 folds at 1.23 V vs RHE and lowers the overpotential for driving the water oxidation, by ~70 mV. The Ni decorated hematite photoelectrode shows a longer decay time (~195 ps) and higher Stern-Volmer constant (5.25 M −1 ) than that of bare hematite photoelectrode (~156 ps and 3.89 M −1 , respectively), implying an efficient charge separation and transfer across the hematite nanorod-Ni nanocrystal heterointerface. Such drastic improvement in the activity is due to the unified effects of enhanced charge separation and charge carrier densities, faster charge transfer kinetics, decreased width of depletion layer, and enhanced band bending – lead by the unison of the nanorod arrays morphology and Ni modification. These results suggest potential candidature of Earth abundant metallic Ni as a co-catalysts (-alternative to noble metals) for designing new photocatalysts. [ABSTRACT FROM AUTHOR]

A nonagon ZnO–ZnFe 2 O 4 nanocomposite was synthesized using high-energy ball milling followed by post-annealing with an initial mixture of high purity magnetite (Fe 3 O 4 ) and zincite (ZnO) powders. The effects of the process parameters on the structural, optical, photocatalytic, and photoelectrocatalytic activities were investigated. X-ray diffraction analysis was used to confirm the presence cubic spinel ZnFe 2 O 4 and hexagonal ZnO crystal phases. The lowest optical bandgap observed was 1.83 eV, which decreased due to post-annealing. The photocatalytic activity of the 800 °C post-annealed nanocomposite exhibited the highest degradation percentage of 96% over 180 min under visible light, with a degradation rate constant of 1.5 min −1 . Furthermore, the optimized sample showed no substantial decrease in photocatalytic activity after five cycles of the repeated catalysis experiment. In electrochemical studies, when compared to the other post-annealed samples, the 800 °C post-annealed nanocomposite showed the highest water splitting activity with the lowest charge-transfer resistance of 75 Ω, photocurrent density of 4.3 × 10 −5  Acm −2 , exchange current density of 4.19 log JA −1  cm −2 , and Tafel slopes of 74.1 mVdec −1 . In dual activities, the performance of the 800 °C post-annealed nanocomposite was noticed to be enhanced. This nanocomposite has potential industrial applications as a cost-effective catalyst. [ABSTRACT FROM AUTHOR]

Ru nanoparticles supported on perovskite NaNbO 3 with cubic crystal structure and nanoflower-like morphology was prepared by a convenient solvothermal method combined with photo-deposition technique. Crystal structure, chemical component and surface valence states determined by XRD, XPS, TEM and SEM demonstrated the metastable cubic phase of perovskite NaNbO 3 , and its modified surface by Ru species. Optical and electrochemical analysis, such as UV–vis DRS, OTCS and EIS, indicated the excellent photoelectrochemical properties and the efficient electron transfer of the composites. Compared with naked and Ru-doped NaNbO 3 , the composite photocatalyst exhibited outstanding performance for the degradation of RhB under visible light irradiation due to the dye self-photosensitization and the surface interaction between Ru metal nanoparticles and semiconductor. In-situ reduction of surface Ru oxide species in the photocatalytic process assisted the further improvement of the photocatalytic activity and stability. Investigation of the main active species during the photocatalysis confirmed the efficient transfer of the photo-generated electrons and the positive effect of oxygen defects in NaNbO 3 . Finally, possible mechanism of the present visible-light driven photocatalysis was proposed in detail. This work provided an alternative strategy to enhance the visible-light photocatalytic efficiency of the catalyst with wide band gap on the basis of the synergistic effect of dye self-photosensitization, interaction between NaNbO 3 and its surface Ru nanoparticles, and the “self-doping” of oxygen defects in NaNbO 3 . [ABSTRACT FROM AUTHOR]

The titanate nanotube/single-wall carbon nanotube (TNT/SWCNT) nanocomposites from different titania precursors were prepared by a two-step hydrothermal process. These nanocomposites were characterized by XRD, BET, Raman, FESEM, TEM, EDX, EDS, EIS, UV–vis DRS and FTIR techniques. The FESEM and TEM images showed the high porous nanocomposites with two types of tubular structure relating to TNTs and SWCNTs which were interwoven together uniformly. The XRD and Raman analysis further corroborated the chemical interaction between the SWCNT and the TNT in the nanocomposites. The photocatalytic performance of the as-synthesized composites were examined by the photodegradation of 4-CP under solar and UV illumination. The results revealed an impressive enhancement in photocatalytic activity of the nanocomposites under both irradiation conditions comparison to bare TNPs and TNTs. Amongst the TNT/SWCNT nanocomposites, 10% loading of SWCNT under UV irradiation and 5% loading of SWCNT under solar irradiation exhibited the maximum photocatalytic performance while the photocatalytic degradation efficiency of nanocomposites were not affected considerably by the type of precursor. Moreover, the mechanism and role of SWCNT were investigated and the plausible degradation pathways of 4-CP was suggested. TOC analyses was performed for determination of 4-CP mineralization rate and results showed complete mineralization after 240 and 390 min under UV and solar irradiation, respectively. The trapping experiments corroborated the O 2 − and OH radicals as the main reactive species in 4-CP degradation process. Langmuir-Hinshelwood kinetic model was fittingly matched with the experimental data (R 2 : 0.9218 and 0.9703 for UV and solar irradiation). Additionally, the stability of the nanocomposites were investigated and revealed 8% decrease in degradation efficiency after four cycles. [ABSTRACT FROM AUTHOR]

Constructing high-quality earth-abundant semionconductor/cocatalyst heterojunction remains a grand challenge in the promising fields of photocatalytic solar fuel H 2 production. Herein, an intimate g-C 3 N 4 nanosheet/NiS cocatalyst heterojunction is fabricated by in situ one-step calcination of urea, thiourea and nickel acetate. Interestingly, thiourea could act as both the precursor of g-C 3 N 4 and the sulfur source of NiS. The H 2 -evolution activity of as-obtained photocatalysts was tested in a triethanolamine (TEOA) scavenger solution under visible light irradiation. Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) mapping analysis clearly demonstrated that the NiS catalyst nanoparticles could be in situ fabricated and homogeneously distributed on the surface of g-C 3 N 4 nanosheets without an obvious aggregation. The maximum H 2 -production rate of 29.68 μmol h −1 could be achieved, which is nearly comparable to that of 0.5 wt% Pt loaded sample. It is believed that the intimate heterojunction interfaces between NiS nanoparticles and g-C 3 N 4 nanosheets could be in situ constructed by high temperature calcination, which achieved the improved charge separation, the enhanced oxidation ability of TEOA and the accelerated the sluggish H 2 -evolution kinetics, thus resulting in the remarkably enhanced hydrogen evolution. Therefore, our study provides insights into constructing high-quality robust g-C 3 N 4 -based heterojunction material for photocatalytic applications by using a simple one-step in-situ calcination technique. [ABSTRACT FROM AUTHOR]

Perovskite solar cell is a novel photovoltaic technology with the superior progress in efficiency and the simple solution processes. Develop lead-free or lead-reduced perovskite materials is a significant concern for high-performance perovskite solar cell. Among the alkaline earth metals, the Sr 2+ and Ba 2+ are suitable for Pb 2+ replacement in perovskite film due to fitting Goldschmidt's tolerance factor. In this study, we adopted Ba-doped and Sr-doped perovskite structured materials with different doping levels, including 1.0, 5.0, and 10.0 mol%, to prepare perovskite solar cells. Both Ba-doped and Sr-doped perovskite structured materials have a related tendency in absorption behavior and surface morphology. At 10.0 mol% doping level, the power conversion efficiency (PCE) of Sr-doped perovskite solar cells is only ∼0.5%, but the PCE of Ba-doped perovskite solar cells can be achieved to ∼9.7%. Ba-doped perovskite solar cells showed the acceptable photovoltaic characteristics than Sr-doped perovskite solar cells. Ba dopant can partially replace the amount of lead in the perovskite solar cells, and it could be a potential candidate in the field of lead-free or lead-reduced perovskite energy materials. [ABSTRACT FROM AUTHOR]

Solar fuels have proven to be one of the important promising approaches to provide clean energy of H 2 . It is an effective strategy for H 2 production to construct photocatalytic systems using semiconductor as a sensitizer and molecular catalyst as the H 2 evolution catalyst. In the semiconductor-molecular photocatalyst systems (SMP systems) for proton reduction, the interfacial charge transfer, including electron and hole transfer, is the determining factor for the photocatalytic process from kinetic aspects. The knowledge of the interfacial charge transfer is of utmost importance for understanding the photocatalytic systems. This review focuses on the interfacial charge transfer in SMP systems for proton reduction, with a special emphasis on the advances in the studies on the kinetic aspects of interfacial charge transfer. [ABSTRACT FROM AUTHOR]

Semiconductor photocatalysis is a promising method to remove the harmful compounds into harmless molecules. Herein, In-doped BiOI (In-BiOI) photocatalysts with highly exposed dominant {001} facets were synthesized through a facile hydrothermal method. The XRD, SEM and TEM determinations revealed the high crystallinity structure of the samples, and the XPS results confirmed the doping of In. The In-BiOI nanosheets exhibited a higher activity in the photodegradation of p -chloroaniline (PCA) than that of pristine BiOI, among which the In-2 BiOI sample (feed mole ratio of In:Bi = 2%) possessed the best performance. Doping with In didn’t alter the structure, morphology, specific surface area or light absorption capacity of BiOI, but significantly improved its charge separation efficiency and transport capability, which were verified by the results of the lower PL emission, larger photocurrent intensity and smaller arc radius of EIS plots. More importantly, the mechanism of photocatalytic degradation is studied systematically, revealing that O 2− and h + were the major reactive species during the photodegradation process. Finally, the possible role of In-doping in enhancing the photocatalytic performance of BiOI is proposed. [ABSTRACT FROM AUTHOR]

The work demonstrates a three-fold increase in photoelectrochemical efficiency of hematite nanorods as a result of the combination of Hafnium surface doping and the incorporation of a ZrO 2 underlayer on FTO. While the ZrO 2 layer reduced the electron loss from the back-injection into the FTO contact support, Hafnium surface doping did not significantly alter the hematite lattice structure. But rather, Hafnium induced nanorod diameter reduction from 32 ± 2 and 26 ± 2 nm, with a consequent increase in the active surface area. The linear sweep voltammetry measurements with 100 mW cm−2 illumination in a 500 nm photoanode thickness showed a photocurrent density of 2.07 mA cm−2 at 1.23 V in a reversible hydrogen electrode (RHE). The value contrasts with the bare hematite rods (0.75 mA cm−2), highlighting the photoanode design's role in improving solar power hydrogen production. [ABSTRACT FROM AUTHOR]