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2D semiconductor nanomaterials have received significant attention as photocatalysts for solar‐to‐hydrogen conversion due to their robust light absorption capacity, large specific surface area, and superior electron transport characteristics. Nevertheless, it is challenging to develop 2D quaternary copper‐based sulfides (QCSs) with functional integration of conducive structural features for photocatalysis from multiple elements and intricate control conditions. Herein, ultrathin 2D alloyed Cu−Ga−Zn−S (CGZS) curved nanobelts (NBs) are fabricated by using a facile one‐pot colloidal method. Subsequently, the derived Cu31S16‐CGZS Janus heterostructures are designed by increasing Cu concentrations. The formation mechanism of 2D curved alloys and Janus heterostructures is systematically investigated. Without cocatalysts, curved alloyed CGZS NBs demonstrated superior photocatalytic activities of 1264.2 µmol g−1 h−1 compared to Janus heterostructured Cu31S16−CGZS (463.1 µmol g−1 h−1) under visible light (> 400 nm). Experimental and theoretical results unveiled that the improved photocatalytic activities of curved CGZS NBs can be attributed to enhanced charge–carrier separation efficiency resulting from high crystallinity and ultrathin 2D structure, abundant active sites from curved structure, high‐active (0001) crystal facet with the lowest reaction Gibbs energy, work function, and metal‐like properties. This work offers new insights into functional integration into ultrathin 2D QCSs with enhanced visible‐light photocatalytic performance. [ABSTRACT FROM AUTHOR]

As an advanced signal source, laser is very suitable for various photonic devices but implementing tunability of wavelength is more challenging. Herein, the study designs and synthesizes boron difluoride derivative tBuBF2, systematically studying the impact of assembly behavior on laser performance. The laser test results indicate that the emission wavelength of tBuBF2 microcrystals can be controlled by varying the length of the microcrystals, with the shorter wavelength of 0–1 vibronic lasing emission at 444 nm and the longer wavelength of 0–2 lasing emission at 468 nm. Mechanistic studies reveal that laser color change comes from an increase in optical propagation losses due to self‐absorption at the 0–1 vibronic band. Furthermore, CBP@tBuBF2 microcrystals constructed by doping with 4,4′‐bis(9‐carbazolyl)‐1,10‐biphenyl (CBP) as the guest molecule, which primarily exhibits 580 nm exciplex yellow emission while retaining weak blue emission. Moreover, it is demonstrated that the laser emission only occurred within the 0–2 vibronic band in the blue region owing to the increased self‐absorption phenomenon with 0–1 band, thus achieving controllable dual‐wavelength and exciplex emission for laser concealment. This work expands novel regulation strategy available for laser behavior control by enhancing the self‐absorption process, describing structure‐property relationships that will guide the design of advanced laser materials. [ABSTRACT FROM AUTHOR]

Quaternary copper-based sulfides (QCSs) exhibit significant potential for solar hydrogen evolution due to their diverse compositions and structures, suitable band structure, controllable synthesis, and non-toxic nature. Strengthening cognition for nanostructures enables the fabrication of high-efficiency photocatalysts. Although a comprehensive understanding of photocatalytic processes of QCS-based photocatalysts has been recently accumulated, the correlation between structure and function remains incompletely elucidated. This overview begins with an introduction to the fundamental principles of solar hydrogen evolution. Subsequently, we provide a succinct description of the controllable synthesis of QCS-based photocatalysts. The structure–function correlation of single QCSs is systematically discussed by exploring how structure-related properties influence photocatalytic processes. Recent advancements based on single QCSs are described in detail. As a guide, we further discuss the structure–function correlation of QCS-based derivatives including semiconductor heterojunctions, cocatalyst loading, heteroatom doping, and polytypic homojunctions. Different mechanisms of activity enhancement are provided along with a summary of their research progress in solar hydrogen evolution. In conclusion, challenges and prospects for materials synthesis and energy conversion are proposed. We anticipate that this overview will offer valuable insights for future exploration of QCS-based photocatalysts, greatly advancing the progress in this emerging research field. [ABSTRACT FROM AUTHOR]

I–III–VI-group semiconductor nanocrystals (NCs) have received extensive attention for use in quantum-dot light-emitting diodes (QLEDs) due to their nontoxic nature, large-scale tunable emission wavelength and straightforward synthesis. At present, research on ternary CuGaSe2 (CGSe) NCs is gradually being carried out. CGSe-based semiconductor NCs with a wide and tunable bandgap exhibit significant promise for efficient QLEDs preparation. In order to improve their functionality, stability and dispersion, Zn2+ was introduced into CGSe cores, which were coated with wide-band-gap ZnS to form Cu–Ga–Zn–Se/ZnS NCs to improve their luminescence performance. In this work, a series of Cu–Ga–Zn–Se/ZnS NCs with tunable emission from 603 to 524 nm and a photoluminescence quantum yield (PLQY) of 96% could be acquired by precisely controlling the non-stoichiometric Cu : Ga molar ratios in the synthesis of the CGZSe cores. Furthermore, green luminescent CGZSe/ZnS NCs were obtained by adjusting the amount of crucial Zn precursors during nucleation and shell formation. The green QLEDs based on these NCs show a high external quantum efficiency of 5.8% and a high brightness of 7016 cd m−2. This work reveals new possibilities for the design of novel and efficient Cd-free green QLEDs. [ABSTRACT FROM AUTHOR]

Currently, the performance of quantum‐dot light‐emitting diodes (QLEDs) based on environmental‐friendly Cu─In─Zn─S quantum dots (QDs) still lags far behind that of Cd‐QDs‐based devices. Here it is demonstrated that the unique trap‐related recombination in Cu─In─Zn─S QDs is mainly responsible for the low device efficiency. The luminous efficiency of Cu─In─Zn─S‐based QLEDs is rather sensitive to the temperature and hole‐transporting layers (HTLs) due to the susceptible thermal‐related trappingdetrapping processes of holes in radiative Cu‐related traps. The holes in Cu‐related traps can be quenched by escaping to the valence band of the QDs or/and transferring to the adjacent HTLs. An HTL with low highest occupied molecular orbitals is desired to enhance the hole injection and hinder the aforementioned hole transfer. As a result, a high device efficiency of 6.0 cd A−1 is achieved at room temperature, which is attributed to suppressed HTL‐induced emission quenching and efficient valence‐band‐dominated hole injection from HTL to the QDs. The device efficiency is further increased to 13.2 cd A−1 at 150K by suppressing thermal‐induced quenching. [ABSTRACT FROM AUTHOR]

Cu-based halide perovskites have attracted extensive attention in the optoelectronic field owing to their non-toxic nature and excellent stability. Nevertheless, the growth mechanism of Cu-based halide perovskite nanocrystals (NCs) remains unclear, and the size and uniformity of NCs are difficult to control, which seriously hinders the development of these materials. Herein, a facile hot-injection method was applied to control the size and uniformity of blue-emitting (450 nm) Cs3Cu2I5 NCs. The dimensions of Cu-based perovskites were tuned from zero-dimensional NCs to one-dimensional nanorods. Additionally, the sizes of Cs3Cu2I5 NCs could be tuned from 22.1 ± 1.5 to 8.9 ± 1.1 nm by varying the reaction temperature and the dosage of cesium oleate, which is also extended to tune the size of Cs3Cu2X5 (X = Br and Cl) NCs. Interestingly, the photoluminescence (PL) maximum at 450 nm was almost unchanged with the size tuning, indicating that PL is from the radiation recombination of self-trap exciton emission. Moreover, the phase transition temperature of Cs3Cu2X5 NCs was regulated by varying the size, where a small size is beneficial to the decrease of the phase transition temperature. As a demonstration, the different-sized Cs3Cu2X5 NCs exhibited a size-dependent temperature response, and the response time became shorter as the size decreased. The temperature response of the small-sized Cs3Cu2X5 NCs could be decreased to only 15 s, which is better than that of their counterparts reported previously. This work may deepen the understanding of the size-dependent phase transition process in Cu-based perovskite NCs. [ABSTRACT FROM AUTHOR]