ABSTRACT Broadband near‐infrared (NIR) light‐emitting materials are essential for developing the next generation of intelligent NIR light sources. Emerging halide perovskite materials are considered highly promising candidates in the field of optoelectronics due to their excellent optical properties and suitability for solution‐based fabrication. However, achieving efficient and thermally stable broadband NIR photoluminescence in these materials remains a significant challenge. In this study, a zirconium (Zr) alloying strategy was employed to modify the vacancy‐ordered double perovskite Cs 2 WCl 6 , significantly enhancing its broadband NIR photoluminescence and enabling the tunability of its optical bandgap. A series of Cs 2 W 1‐x Zr x Cl 6 samples (0 ≤ x ≤ 1) were successfully synthesized, with the optical bandgap expanding from 1.17 eV for x = 0 to 3.26 eV for x = 1. The Zr 4+ ‐alloyed material exhibited a 24‐fold increase in NIR photoluminescent quantum yield and an extension of the exciton lifetime from 9.94 to 42.77 µs. Furthermore, density functional theory (DFT) calculations and temperature‐dependent photoluminescence spectra indicate that Zr 4+ alloying optimizes the microstructural environment of the Cs 2 WCl 6 luminescent centers. This process weakens electron‐phonon coupling and breaks parity‐forbidden transitions of [WCl 6 ] 2− . The study demonstrates the effectiveness of metal ion alloying in tuning the bandgap and enhancing NIR photoluminescence in double perovskites.

Halide double perovskites with near-infrared (NIR) emission are promising for optoelectronic applications. NIR-II (1000–1700 nm) emission, in particular, is attractive due to its strong tissue penetration, high spatial resolution, and low biological light damage risk. However, materials capable of NIR-II emission often require additional sensitizers and suffer from issues such as narrow emission bandwidth and low photoluminescence efficiency. In this work, we report a Re4+ doping strategy using Cs2WCl6, a vacancy–ordered double perovskite, to achieve efficient NIR-II emission. Spectroscopic and dynamic measurements reveal energy transfer between the Cs2WCl6 matrix and the Re4+ centers, resulting in efficient broadband NIR-II emission centered at 1345 nm (FWHM ≈ 87 nm), along with broad excitation ranging from 250 to 850 nm. The optimal NIR-II emission occurs at 1345 nm with a photoluminescence quantum yield (PLQY) of 29.83% when the Re4+ doping concentration is 1%. This work demonstrates an efficient, sensitizer-free method for achieving broadband NIR-II emission and provides a new material strategy for high–performance double perovskites NIR light sources.

All-inorganic CsPbX3 (X = Cl, Br, I) perovskites have demonstrated great potential for optoelectronic applications due to their excellent optical properties and environmental stability. Random lasing is a particularly promising direction because of its simple and cavity-free feedback mechanism. However, efficient random lasing in CsPbX3 thin films remains challenging because of their high defect densities, non-radiative recombination rate, and poor surface morphology. Herein, we present a simple method to fabricate high-quality CsPbBr3 thin films, using polymethyl methacrylate-toluene solution as antisolvent, which simultaneously enables surface passivation of perovskite crystals. The as-synthesized films exhibit improved crystallinity, smoother morphology, and prolonged carrier lifetime. Owing to these factors, the films achieve a low threshold random lasing (9.59 & micro;J/cm(2)), along with an ultrafast photon decay of 3.14 ps at 2.4 times the threshold. Notably, the random lasing can be realized across the sample area. This work highlights the effect of polymer passivation in enhancing film quality and enabling low-threshold, short-pulse random lasing. These findings provide a promising strategy for large-area, multi-point integrated photonics applications based on perovskite thin films.

Lead-free Cs3Cu2I5 perovskite nanocrystals (NCs) are promising candidates for optoelectronic applications owing to their non-toxicity and intrinsic blue emission. However, their practical application is hindered by defect-dominated low photoluminescence quantum yield (PLQY) and poor environmental stability. Herein, we propose an ultrafast liquid-nitrogen (LN) quenching strategy integrated with one-pot synthesis, which delivers an ultra-high cooling rate of 35 K/s faster than conventional ice-water (IW) cooling (1 K/s). This abrupt thermal termination effectively suppresses Ostwald ripening, ion migration and surface ligand detachment, thereby promoting uniform size distribution, inducing lattice contraction and reducing the non-radiative defects. The obtained Cs3Cu2I5 NCs exhibit a remarkable PLQY up to 85% and exceptional stability, maintaining beyond 80% of initial PL intensity after ambient storage for 35 days, aqueous exposure for 36 hand continuous UV irradiation for 48 h. Moreover, the LN-quenched NCs were successfully integrated into X-ray scintillator film achieving a spatial resolution of 10 lp/mm, and their colloidal ink enabled stimulus-responsive information encryption and fluorescence anti-counterfeiting patterns, attributed to enhanced self-trapped exciton (STE) emission and robust structural integrity. This work establishes ultrafast LN quenching as a universal and feasible strategy for fabricating highly luminescent and stable perovskite NCs, paving the way for multifunctional optoelectronic applications.

ABSTRACT Strain‐induced wavelength‐tunable flexible lasers hold considerable promise in wearable devices and multifunctional electronic skin. Furthermore, their dynamic pulse parameter adjustability with picosecond‐level temporal resolution provides extended potential in high‐precision dynamic monitoring, high‐speed anti‐interference communication, and precision sensing. Here, we report a flexible CsPbBr 3 perovskite microlaser with spectral tunability of 1.59 nm in wavelength and 14 ps in laser pulsewidth through mechanical stress modulation. The device exhibits a low threshold density of <2 µJ/cm 2 , a high respond speed with a delay time of <70 ps, and an ultrashort optical pulse with a minimum duration of 10.8 ps. The strain‐induced evolution of the gain‐switched pulsed laser outputs, including pulsewidth, delay time, and photon decay were systematically explored, for the first time, by taking the strain–photon synergetic coupling mechanism into account. Additionally, the stress dependences of the laser pulse behaviors are physically revealed by theoretical simulations using the Hamiltonian matrix combined with rate equations. Our results provide not only a better understanding of lasing in flexible perovskite microcavity systems under stress, but also a new platform for high‐precision stress monitoring by picosecond‐level pulsewidth sensing.

Halide perovskites (HPs) are among the most promising semiconductor candidates for ultrashort pulse generation due to their intrinsic high material gain and ultrafast carrier dynamics. By introducing an ingeniously-designed cavity structure, picosecond (ps) or even femtosecond (fs) laser pulses can be plausibly obtained from the perovskite devices for a wide variety of applications. A comprehensive understand of the carrier density dependence of exciton transport and recombination as well as light‒matter interaction can help researchers gain deeper insight into the ultrashort pulse generation during lasing. Here, an overview of the recent progress on ultrafast charge carrier dynamics in 3D bulk single-crystal perovskites as well as quantum-confined 2D/quasi-2D Ruddlesden–Popper perovskites and 0D perovskite nanocrystals/quantum-dots is provided. Additionally, state-of-the-art developments in pulse generation from various perovskite lasers are summarized, with particular attention paid to gain-switched ultrashort laser pulse emission in different HP microcavities. The physical mechanisms that influence the pulse characteristics of HP lasers based on a rate equation model is also discussed. Finally, the challenges and future prospects of HPs in realizing ultrashort fs-optical pulses for practical applications are discussed emphatically.

Antimony chalcogenide (Sb2(S, Se)3) semiconductor has recently emerged as a popular photovoltaic material for thin-film solar cells because of its high light absorption coefficient and tunable absorption band gap. The vapour transport deposition (VTD) approach has shown promise in fabricating Sb2(S, Se)3 solar cells. However, conventional VTD depends on varying substrate positions for managing the temperature differential between source and substrate. This phenomenon leads to unstable film flaws that trigger a decline in open-circuit voltage (VOC) and the development of profound-level defects. Therefore, a novel method for fabricating Sb2(S, Se)3 solar cells based on a double-temperature evaporation furnace named substrate temperature-controlled vapour transport deposition method (STC-VTD) is presented in this study. The initial application of the modified VTD method yielded a solar cell with a power conversion efficiency (PCE) of 7.56 %, which is the highest PCE obtained through single evaporation VTD. Deep-level transient spectroscopy measurements reveal that the defect levels generated in the solar cells are passivated via the STC-VTD method. This work proposes substrate temperature-independent control for other physical vapour preparation methods, paving a new direction for further applications of vapour transport technology.

High indium composition in green-light InGaN/GaN light-emitting diodes (LEDs) can lead to significant efficiency degradation, which has not been comprehensively resolved. We made a systematic investigation of high efficiency green InGaN LEDs with the insertion of superlattices (SLs) and their epitaxial wafers. We elucidated the mechanistic role of SLs in suppressing the localization effect mainly by temperature-dependent photoluminescence (PL). Further corroboration of the good crystalline quality is provided via power-dependent PL and thermal admittance spectroscopy (TAS). The homogeneity of indium composition could suppress the Shockley–Read–Hall recombination significantly: a radiative efficiency of more than 44.7% at 300 K was achieved, and no identifiable defect levels were found by TAS. However, the overall radiative efficiency was still limited due to electron crowding in the quantum well closest to the p-type region and inadequate hole injection, illustrated by the capacitance–voltage measurements and the simulation results with the finite element method. Our analysis along with the introduced improvement strategy could provide relatively comprehensive guidance for subsequent designs.

Perovskite nanocrystals (NCs) are suffering from severe instability issue, which seriously restricts their practical applications. Herein, a novel double surface modulation strategy is proposed to prepare high-quality organicinorganic hybrid encapsulated CsPbBr3 NCs. The first surface passivation is performed by introducing a new type ionic liquid (IL) 1-butyl-3-methylimidazolium dicyanamide ([Bmim]N(CN)2) with abundant N-related functional groups into the synthesis process of NCs, in which the cation and anion of the IL can eliminate the bromide vacancy and Pb-related defects of NCs, leading to the increase of PLQY to 85.28 %. In addition, the dual protective shells consisting of cross-linked organosilicon (SiOx) and polystyrene-block-polyisoprene-blockpolystyrene (SIS) are further employed to encapsulate CsPbBr3 cores, which can provide effective protection for NCs. As a result, the as-prepared CsPbBr3@SiOx@SIS composites present a high PLQY of 92.10 % and improved stability. Moreover, green LEDs are also fabricated, the CsPbBr3@SiOx@SIS based device presents higher luminous efficacy and long-term operation stability compared to the CsPbBr3 based device. Finally, a white LED device with International de I'Eclairage (CIE) coordinates of (0.31, 0.32) is assembled, approaching the standard white light. The findings underscore the significance of surface property for modulating the emission performance and stability of perovskite NCs, paving the way for their practical applications.

Multijunction solar cells (MJSCs) experience material degradation and reduced efficiency during long-term storage. Current defect analysis methods for III-V compound MJSCs are limited by a lack of intuitive tools and in-depth understanding, hindering improvements in yield and efficiency. Absolute electroluminescence (EL) is a powerful technique for visualization and predicting solar cell performance. In this study, we applied absolute EL to quantify performance and degradation mechanisms in subcells after 26 months of storage. Absolute EL imaging identified both potential and inherent defect types within the subcells. The detailed analysis of localized defect points showed reduced photon emission near the defect points. Using the reciprocity theorem and carrier balance model, we found that degradation in the InGaP/GaAs/InGaAs solar cell resulted in a 0.8% reduction in efficiency, largely due to nonradiative recombination (NR) losses. Additionally, the efficiencies of top, middle, and bottom cells decreased by reduced by 0.3%, 0.2%, and 0.3%, respectively. This work demonstrates that the absolute EL imaging technique provides a comprehensive and detailed method for understanding defects and energy losses during long-term storage in MJSC.

The poor stability of CsPbBr3 perovskite nanocrystals (PNCs) caused by weak and dynamic ligand coordination severely limits their commercial applications. Herein, a dual-ligand synergistic modification strategy based on bromocarboxylic acids (BCAs) and oleylamine (OAm) was developed to mediate the surface structures and luminescent dynamics of CsPbBr3 PNCs. The results reveal that carboxylate groups of BCA ligands modulate crystal growth, while its terminal Br atom forms a strong coordination with exposed Pb2+ on the PNCs surface, which can effectively passivate lead- and bromine-related defects. The synergistic protection of OAm ligands enhances the stability of PNCs via amino-halide electrostatic interactions and steric hindrance effects. Notably, based on the relatively dense surface coating of 4-bromobutyric acid (BBA) and OAm dual-ligands, the prepared CsPbBr3 PNCs exhibit a high photoluminescence quantum yield (PLQY) of 85.2 ± 2.4% and remarkable storage stability, retaining 90.2 ± 1.7% of their initial PL intensity after being stored for 63 days under ambient conditions. Furthermore, a prototype white light-emitting diode (WLED) fabricated with these PNCs displays a wide color gamut covering 122.1% of the NTSC standard and a luminous efficacy of 64.6 lm/W. This work provides a facile and feasible ligand engineering strategy to obtain highly stable and emissive PNCs.

Antimony selenosulfide [Sb2(S,Se)3] solar cells fabricated via the hydrothermal process have garnered significant attention due to their exceptional optoelectronic properties. However, Sb2(S,Se)3 thin films continue to encounter obstacles, such as low crystallinity, rough surface morphology, and uneven elemental distribution, all of which impede device performance. This study introduces sodium chloride (NaCl) as an interfacial modification layer to enhance the crystallinity, morphology, defect density, and overall optoelectronic performance of the films. NaCl post-treatment improves the crystallinity, reduces the defect density, and refines the surface morphology. Water contact angle measurements decreased from 69.63° to 53.63°, demonstrating enhanced hydrophilicity, which promotes uniform hole transport layer deposition and reduces pinholes. Electrochemical impedance spectroscopy shows an increase in recombination resistance (Rrec) from 4.2 to 4.8 kΩ, indicating reduced carrier recombination and improved charge transport efficiency at the interface. Ultimately, NaCl post-treatment enhanced the power conversion efficiency of Sb2(S,Se)3 solar cells from 6.63 to 8.30%, illustrating the effectiveness of this modification in optimizing the performance of Sb2(S,Se)3 solar cells.

Three-dimensional distributed circuit modeling based on SPICE software can simulate the electrical performance and the uniformity of electroluminescence (EL) intensity. To solve the problem that traditional methods require manual iteration to determine the device parameters of the simulation model, we proposed an efficient automated quantitative analysis method that can quickly diagnose the localized series resistor (RS-MC) of the dark-spot defects in GaAs solar cells via absolute EL images. This method employs a one-dimensional convolutional neural network model based on a multi-scale and convolutional block attention module (CBAM-MS-1DCNN). A medium dataset consisting of 200,000 defects from 250 simulated solar cells to train the CBAM-MS-1DCNN model, where the coefficient of determination (R2)>0.95 and the normalized root mean square error (NRMSE)<5%, indicating that the proposed model can predict RS-MC well. Furthermore, the relative error of the predicted absolute EL intensity based on real samples can be controlled within 10% using the CBAM-MS-1DCNN model. The model trained on the simulated dataset has good prediction performance for real GaAs solar cells, which provides ideas for the problem of obtaining EL image datasets.

Antimony selenide (Sb2Se3) has emerged as a highly promising photovoltaic absorber owing to its cost-effectiveness and distinctive one-dimensional crystal structure. Recent research has increasingly focused on crystal orientation engineering to improve the efficiency of Sb2Se3-based solar cells. Herein, an Sb2Se3 film prepared by chemical bath deposition was post-treated by open-space annealing (OSA) and close-space annealing (CSA). The two annealing methods resulted in different temperature distributions on the surface of the films, and the films showed a significantly different grain growth model and preferred orientation. The [301]- and [311]-oriented Sb2Se3 films were obtained following the normal grain growth model during close-space annealing. Enhanced grain orientation can substantially enhance carrier transport. Furthermore, close-space annealing can effectively passivate film defects. Finally, solar cells based on CSA-Sb2Se3 thin films achieved a power conversion efficiency (PCE) of 8.57%. This study provides a new insight for the orientation engineering of quasi-one-dimensional thin-film materials.

Antimony selenide (Sb2Se3) as a light-harvesting material has garnered significant attention for its excellent photoelectric properties. The quality of the absorption layer plays a crucial role in efficiency improvement. Here in, methanol serves as a solvent auxiliary additive to enhance Sb2Se3 film quality effectively that deposited by chemical bath deposition. The introduction of methanol effectively regulates the release of SbO+ and influences the growth kinetics during the reaction, resulting in larger grain sizes, a smoother morphology, and enhanced purity of the film. Moreover, the film’s charge recombination ability is effectively reduced and its photoelectric performance is enhanced due to the improved film quality, thus acquiring a maximum efficiency of 8.03%, which is 40% higher than the control device. This study is significant for the fabrication of higher quality Sb2Se3 thin films and solar cells by chemical bath deposition.

All-inorganic perovskite materials have been widely used in various devices, including lasers, light-emitting diodes (LEDs), and solar cells, due to their exceptional optoelectronic properties. Devices utilizing high-quality single crystals are anticipated to achieve significantly enhanced performance. In this work, we present a high-performance vertical cavity surface emitting laser (VCSEL) based on a single-crystal CsPbBr3 microplatelet, fabricated through a simple solution process and sandwiched between two distributed Bragg reflector (DBRs). The VCSEL demonstrated single-mode lasing at 542 nm, a low threshold of 5 mu J/cm2, and a high Q-factor of 2893. Additionally, time- resolved photoluminescence (TRPL) measurements using a streak camera revealed picosecond-scale lasing dynamics. This study offers a novel, to the best of our knowledge, approach for realizing laser devices using perovskite single- crystal microplatelets. (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.

Perovskite quantum dots (PQDs) have garnered significant attention as promising gain media for laser applications due to their excellent optical properties. However, the dynamic binding behavior of conventional long-chain insulating ligands (oleic acid/oleylamine, OA/OAm) to QD surfaces inherently generates unfavorable defect states, exacerbating nonradiative recombination and fundamentally limiting their optoelectronic performance. In this work, we report a facile room-temperature synthetic strategy for high-performance CsPbBr3 PQDs by utilizing beta-cyclodextrin (beta-CD) instead of a mixed OA/OAm solution as a ligand. The beta-CD-encapsulated CsPbBr3 PQDs present a maximum of 556% enhancement in photoluminescence (PL) intensity under an ambient environment compared to the OA/OAm-ligand counterparts. The pump power-dependent PL measurements reveal a 38% higher internal quantum efficiency, and further analysis based on a Bose-Einstein statistical model indicates a reduced defect density and superior excitonic recombination in such beta-CD-modified PQDs. Additionally, by employing the PQDs as a gain medium, we successfully demonstrate a room-temperature single-mode surface-emitting laser with stable outputs and a low lasing threshold. This work not only presents a significant step forward in PQD synthesis and surface ligand engineering but also provides guidance for developing high-performance optoelectronic devices.

Cadmium sulfide (CdS) is widely employed as the electron transport layer due to its ability to form dense films in the fabrication of antimony selenosulfide (Sb2(S, Se)3) solar cells. However, it presents significant drawbacks: its toxicity poses environmental risks, and its narrow bandgap restricts the collection of higher-energy carriers. Titanium dioxide (TiO2) stands out as a viable and environmentally friendly alternative, offering features, such as high optical transparency, excellent stability, and nontoxic characteristics, making it highly suitable for application in Sb2(S, Se)3 thin-film solar cells. In our study, we employed a sodium chloride (NaCl) solution treatment to enhance the quality of TiO2 films grown via the chemical bath deposition (CBD) method. The Na ions introduced during postannealing play a pivotal role in optimizing the interface between the TiO2 and Sb2(S, Se)3 layers. This treatment enhances the bandgap of the TiO2 layer, improving electronic coupling at the p-n junction. This process significantly boosts device performance, including the short-circuit current density (JSC) and open-circuit voltage (VOC). As a result, the power conversion efficiency (PCE) of the TiO2/Sb2(S, Se)3 heterojunction solar cells improved remarkably from 2.3% to 5.5%. The novel approach highlights the effectiveness of wide-bandgap TiO2 buffer layers in advancing Sb2(S, Se)3 solar cells. By overcoming the limitations of traditional CdS layers and integrating Na ion-enhanced TiO2 films, this study demonstrates a promising route for achieving high-efficiency and environmentally sustainable solar cells.

The effects of localized tensile stress (LTS) on Gallium Arsenide (GaAs) solar cells were investigated using an innovative methodology that integrated absolute electroluminescence (EL) imaging with three-dimensional (3D) distributed circuit modeling. Absolute EL imaging and spectra analysis revealed an enhancement in EL intensity and a red-shift in the EL emission peak within LTS-affected regions. The observations were well-interpreted by changes in the localized energy band structure. Utilizing the absolute EL image and spectra, the stress distribution on the surface of the GaAs solar cell after introducing LTS could be quantitatively determined. To quantify the observations from an electrical perspective, a 3D distributed circuit model of the GaAs solar cell was established. This model demonstrated that LTS led to a decrease in localized series resistance and an increase in localized shunt resistance. By introducing LTS, our model predicted a power conversion efficiency (PCE) increment in the solar cell under AM 1.5G 1-sun illumination, which was confirmed by the experimentally observed PCE increment. This research provided a comprehensive approach for analyzing and understanding the effects of mechanical localized stress on photovoltaic devices.