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The quaternary chalcogenide Cu2NiSnS4 (CNTS) nanoparticles, made up of earth-abundant elements, are one of the most favorable in the family of CMxTS (Mx = Ni, Co, Cd, Fe, Mg, Mn, and Zn) for photoelectrochemical (PEC) hydrogen production due to the lowest resistivity, high absorption coefficient, and tunable band gap for sunlight absorption with suitable band edges. A p-type semiconductor, CNTS, is one of the stable photocathodes in the category of efficient ones. In this theoretical-aided experimental work, we illustrate the photoelectrochemical credibility of CNTS nanomaterials synthesized by a facile hot-injection method with CdS as a photoanode for hydrogen evolution with the interface of an alkaline electrolyte. Using density functional theory simulations, charge density difference, work function, and structural properties were evaluated, suggesting better lattice matching at the CNTS/CdS supercell interface with a lattice mismatch less than 3% along with better charge transfer. An optical band gap of 1.40 eV and a crystallite size of 48 nm were observed for CNTS evaluated. A high short-circuit current density of 6.656 mA cm–2 IPCE for the CNTS/CdS heterojunction was observed to be 14.87% at 505 nm. This promotes the heterojunction to possess minimal chances of material's phase change and hence stability. [ABSTRACT FROM AUTHOR]

SnSe nanomaterials are challenging to use in sustainable energy production due to difficulties in phase-pure synthesis and efficient charge-carrier separation. We demonstrate a systematic facile synthesis method with an in-depth nucleation and growth mechanism for the rational design of phase-pure and morphology-controlled SnSe-based efficient and cost-effective photocatalysts. Transient absorption spectroscopy measurements are performed to investigate the charge-carrier kinetics of SnSe microflowers (MFs), which exhibit a free charge-carrier lifetime of 6.2 ps. Although the bare SnSe, CdSe, and ZnSe photoanodes demonstrate sizable photocurrents, the construction of CdSe/SnSe and ZnSe/SnSe heterojunctions dramatically improves the photoelectrochemical devices activity. The CdSe/SnSe photoanode shows higher photocurrents of 35 μA cm–2, compared to the ZnSe/SnSe (15 μA cm–2) heterojunction and the individual SnSe (10 μA cm–2), CdSe (7 μA cm–2), and ZnSe (1 μA cm–2). The decent photoactivity of the CdSe/SnSe photoanode is attributed to the desired type-II band alignment and very small band offset (0.08 eV) that exists across the interface, which promotes the efficient separation of photogenerated electron–hole pairs confirmed by cyclic voltammetry measurements and is corroborated by first-principles density functional theory calculations. These findings should open new avenues for the design and development of advanced next-generation tin selenide-based heterostructures for efficient PEC water-splitting applications. [ABSTRACT FROM AUTHOR]

The efficiency of mesoporous perovskite solar cells (mp-PSCs) is significantly influenced by favorable charge transport properties across their various interfaces. The interfaces involving compact-TiO 2 , mesoporous electron transport layer (ETL), and perovskite layer are particularly vital for high-performing devices. Our study presents a combined experimental and computational approach, specifically employing density functional theory, to explore the impact of mesoporous-ETL/perovskite interface properties on carrier transport. These properties are examined in relation to the phases and morphologies of the mesoporous layer. Different phases of TiO 2 , including anatase, rutile, and brookite, and various morphologies such as nanocubes, nanorods, and disks/clusters, were synthesized using a simple hydrothermal synthesis route. They constitute the mesoporous layer, and Cs 0.05 FA 0.84 MA 0.14 PbI 2.55 Br 0.45 is used as the perovskite absorber in mp-PSCs. The performance of the resulting mesoporous-TiO 2 (mp-TiO 2 ) device was investigated in relation to the different phases and morphologies of mp-TiO 2 . The mp-PSCs with the anatase phase as the mesoporous ETL exhibited the highest device parameters, including power conversion efficiency of 19.15%, short-circuit current density of 22.55 mA/cm 2 , fill factor of 76.50%, and open-circuit voltage of 1.11 V. The superior performance of the anatase structure is attributed to its promising band edge alignment, which results from a small negative conduction band offset compared to other phases, thereby enhancing carrier transport. This study underscores the potential of interface optimization to improve device performance. By investigating the device performance across different phases and morphologies of the mp-TiO 2 layer, we can pave the way for the design of next-generation energy devices.

Lead-free double perovskites (DPs) will emerge as viable and environmentally safe substitutes for Pb-halide perovskites, demonstrating stability and nontoxicity if their optoelectronic property is greatly improved. Doping has been experimentally validated as a powerful tool for enhancing optoelectronic properties and concurrently reducing the defect state density in DP materials. Fundamental understanding of the optical properties of DPs, particularly the self-trapped exciton (STEs) dynamics, plays a critical role in a range of optoelectronic applications. Our study investigates how Fe doping influences the structural and optical properties of Cs 2 AgBiCl 6 DPs by understanding their STEs dynamics, which is currently lacking in the literature. A combined experimental-computational approach is employed to investigate the optoelectronic properties of pure and doped Cs 2 AgBiCl 6 (Fe-Cs 2 AgBiCl 6 ) perovskites. Successful incorporation of Fe 3+ ions is confirmed by X-ray diffraction and Raman spectroscopy. Moreover, the Fe-Cs 2 AgBiCl 6 DPs exhibit strong absorption from below 400 nm up to 700 nm, indicating sub-band gap state transitions originating from surface defects. Photoluminescence (PL) analysis demonstrates a significant enhancement in the PL intensity, attributed to an increased radiative recombination rate and higher STE density. The radiative kinetics and average lifetime are investigated by the time-resolved PL (TRPL) method; in addition, temperature-dependent PL measurements provide valuable insights into activation energy and exciton-phonon coupling strength. Our findings will not only deepen our understanding of charge carrier dynamics associated with STEs but also pave the way for the design of some promising perovskite materials for use in optoelectronics and photocatalysis., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Considering the importance of physics and chemistry at material interfaces, we have explored the coupling of multinary chalcogenide semiconductor Cu 2 NiSnS 4 nanoparticles (CNTS NPs) for the first time with the noble metal (Au) to form Au-CNTS nano-heterostructures (NHSs). The Au-CNTS NHSs is synthesized by a simple facile hot injection method. Synergistic experimental and theoretical approaches are employed to characterize the structural, optical, and electrical properties of the Au-CNTS NHSs. The absorption spectra demonstrate enhanced and broadened optical absorption in the ultraviolet-visible-near-infrared (UV-Vis-NIR) region, which is corroborated by cyclic voltammetry (CV) readings. CV measurements show type II staggered band alignment, with a conduction band offset (CBO) of 0.21 and 0.23 eV at the Au-CNTS/CdS and CNTS/CdS interface, respectively. Complementary first-principles density functional theory (DFT) calculations predict the formation of a stable Au-CNTS NHSs, with the Au nanoparticle transferring its electrons to the CNTS. Moreover, our interface analysis using ultrafast transient absorption experiments demonstrate that the Au-CNTS NHSs facilitates efficient transport and separation of photoexcited charge carriers when compared to pristine CNTS. The transient measurements further reveal a plasmonic electronic transfer from the Au nanoparticle to CNTS. Our advanced analysis and findings will prompt investigations into new functional materials and their photo/electrocatalysis and optoelectronic device applications in the future.

Tin chalcogenides (SnX, X = S, Se)-based heterostructures (HSs) are promising materials for the construction of low-cost optoelectronic devices. Here, we report the synthesis of a SnSe/CdSe HS using the controlled cation exchange reaction. The (400) plane of SnSe and the (111) plane of CdSe confirm the formation of an interface between SnSe and CdSe. The Type I band alignment is estimated for the SnSe/CdSe HS with a small conduction band offset (CBO) of 0.72 eV through cyclic voltammetry measurements. Transient absorption (TA) studies demonstrate a drastic enhancement of the CdSe biexciton signal that points toward the hot carrier transfer from SnSe to CdSe in a short time scale. The fast growth and recovery of CdSe bleach in the presence of SnSe indicate charge transfer back to SnSe. The observed delocalization of carriers in these two systems is crucial for an optoelectronic device. Our findings provide new insights into the fabrication of cost-effective photovoltaic devices based on SnSe-based heterostructures.

Mixed-halide CsPbI 2 Br perovskite is promising for efficient and thermally stable all-inorganic solar cells; however, the use of conventional antisolvent methods and additives-based hole-transporting layers (HTLs) currently hampers progress. Here, we have employed hot-air-assisted perovskite deposition in ambient condition to obtain high-quality photoactive CsPbI 2 Br perovskite films and have extended stable device operation using metal cation doping and dopant-free hole-transporting materials. Density functional theory calculations are used to study the structural and optoelectronic properties of the CsPbI 2 Br perovskite when it is doped with metal cations Eu 2+ and In 3+ . We experimentally incorporated Eu 2+ and In 3+ metal ions into CsPbI 2 Br films and applied dopant-free copper(I) thiocyanate (CuSCN) and poly(3-hexylthiophene) (P3HT)-based materials as low-cost hole transporting layers, leading to record-high power conversion efficiencies of 15.27% and 15.69%, respectively, and a retention of >95% of the initial efficiency over 1600 h at 85 °C thermal stress., Competing Interests: The authors declare no competing financial interest., (© 2021 American Chemical Society.)

To improve the constraints of kesterite Cu 2 ZnSnS 4 (CZTS) solar cell, such as undesirable band alignment at p-n interfaces, bandgap tuning, and fast carrier recombination, cadmium (Cd) is introduced into CZTS nanocrystals forming Cu 2 Zn 1- x Cd x SnS 4 through cost-effective solution-based method without postannealing or sulfurization treatments. A synergetic experimental-theoretical approach was employed to characterize and assess the optoelectronic properties of Cu 2 Zn 1- x Cd x SnS 4 materials. Tunable direct band gap energy ranging from 1.51 to 1.03 eV with high absorption coefficient was demonstrated for the Cu 2 Zn 1- x Cd x SnS 4 nanocrystals with changing Zn/Cd ratio. Such bandgap engineering in Cu 2 Zn 1- x Cd x SnS 4 helps in effective carrier separation at interface. Ultrafast spectroscopy reveals a longer lifetime and efficient separation of photoexcited charge carriers in Cu 2 CdSnS 4 (CCTS) nanocrystals compared to that of CZTS. We found that there exists a type-II staggered band alignment at the CZTS (CCTS)/CdS interface, from cyclic voltammetric (CV) measurements, corroborated by first-principles density functional theory (DFT) calculations, predicting smaller conduction band offset (CBO) at the CCTS/CdS interface as compared to the CZTS/CdS interface. These results point toward efficient separation of photoexcited carriers across the p-n junction in the ultrafast time scale and highlight a route to improve device performances., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

We report the synthesis of two-dimensional porous ZnO nanosheets, CuSCN nanocoins, and ZnO/CuSCN nano-heterostructure thin films grown on fluorine-doped tin oxide substrates via two simple and low-cost solution chemical routes, i.e., chemical bath deposition and successive ionic layer adsorption and reaction methods. Detail characterizations regarding the structural, optoelectronic, and morphological properties have been carried out, which reveal high-quality and crystalline synthesized materials. Field emission (FE) investigations performed at room temperature with a base pressure of 1 × 10 -8 mbar demonstrate superior FE performance of the ZnO/CuSCN nano-heterostructure compared to the isolated porous ZnO nanosheets and CuSCN nanocoins. For instance, the turn-on field required to draw a current density of 10 μA/cm 2 is found to be 2.2, 1.1, and 0.7 V/μm for the ZnO, CuSCN, and ZnO/CuSCN nano-heterostructure, respectively. The observed significant improvement in the FE characteristics (ultralow turn-on field of 0.7 V/μm for an emission current density of 10 μA/cm 2 and the achieved high current density of 2.2 mA/cm 2 at a relatively low applied electric field of 1.8 V/μm) for the ZnO/CuSCN nano-heterostructure is superior to the isolated porous ZnO nanosheets, CuSCN nanocoins, and other reported semiconducting nano-heterostructures. Complementary first-principles density functional theory calculations predict a lower work function for the ZnO/CuSCN nano-heterostructure (4.58 eV), compared to the isolated ZnO (5.24 eV) and CuSCN (4.91 eV), validating the superior FE characteristics of the ZnO/CuSCN nano-heterostructure. The ZnO/CuSCN nanocomposite could provide a promising class of FE cathodes, flat panel displays, microwave tubes, and electron sources., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)