Copper is relatively low cost and highly abundant compared with the well-studied noble metals such as gold and silver. However, the poor plasmonic and high susceptibility towards oxidation limit the study of its optical properties and applications as well. Herein, copper nanoparticles@polycarbonate (Cu@PC) composites were prepared by using a facile one-step solvothermal method. The Cu@PC composites have strong localized surface plasmon resonances (LSPR) due to that the PC shell can induce the particles to form many-particles system with different particle numbers, which not only lead to overlap and hybridize of the LSPR modes, but also shift the LSPR away from the interband transitions, and the PC layer also prevents the oxidation of Cu nanoparticles. The photothermal conversion efficiency of Cu@PC composites reaches 41.1% under 808 nm continuous wave (CW) laser irradiation which is higher than previously reported Cu nanomaterials that have been reported. Meanwhile, the composites also have high photothermal stability. Moreover, interfacial evaporator is prepared by assembling the Cu@PC composites on scouring sponge as light absorption layer which has > 92.8% absorption in entire solar spectrum range. Its seawater evaporation rate is 3.177 kg·m^–2·h^–1 with a E_evaporator/E_water of 5.2. The high evaporation rate interfacial evaporator with low cost, simple, and scalable approach shows great application value in the field of photothermal evaporation.

Stacking single layers of atoms on top of each other provides a fundamental way to achieve novel material systems and engineer their physical properties, which offers opportunities for exploring fundamental physics and realizing next-generation optoelectronic devices. Among the two-dimensional (2D)-stacked systems, transition metal dichalcogenide (TMDC) heterostructures are particularly attractive because they host tightly-bonded interlayer excitons which possess various novel and appealing properties. These interlayer excitons have drawn significant research attention and hold high potential for the application in unique optoelectronic devices, such as polarization- and wavelength-tunable single photon emitters, valley Hall transistors, and possible high-temperature superconductors. The development of these devices requires a comprehensive understanding of the fundamental properties of these interlayer excitons and the impact of electric fields on their behaviors. In this review, we summarize the recent advances on the understanding of interlayer exciton dynamics under electric fields in TMDC heterostructures. We put emphasis on the electrical modulation of interlayer excitons’ emission, the valley Hall transport of charge carriers after the separation of interlayer excitons by an electric field, and the correlation physics of interlayer excitons and charges under electrical doping and tuning. Challenges and perspectives are finally discussed for the application of TMDC heterostructures in future optoelectronics.

Photoelectric synaptic devices have been considered as one of the key components in artificial neuromorphic systems due to their excellent capability to emulate the functions of visual neurons, such as light perception and image processing. Herein, we demonstrate an optically-stimulated artificial synapse with a clear photoresponse from ultraviolet to visible light, which is established on a novel heterostructure consisting of monocrystalline Cs₂AgBiBr₆ perovskite and indium–gallium–zinc oxide (IGZO) thin film. As compared with pure IGZO, the heterostructure significantly enhances the photoresponse and corresponding synaptic plasticity of the devices, which originate from the superior visible absorption of single-crystal Cs₂AgBiBr₆ and effective interfacial charge transfer from Cs₂AgBiBr₆ to IGZO. A variety of synaptic behaviors are realized on the fabricated thin-film transistors, including excitatory postsynaptic current, paired pulse facilitation, short-term, and long-term plasticity. Furthermore, an artificial neural network is simulated based on the photonic potentiation and electrical depression effects of synaptic devices, and an accuracy rate up to 83.8% ± 1.2% for pattern recognition is achieved. This finding promises a simple and efficient way to construct photoelectric synaptic devices with tunable spectrum for future neuromorphic applications.

Growth of high-quality large-sized crystals using the traditional chemical vapor transport (CVT) or vertical Bridgman (VB) technique is costly and time-consuming, limiting its practical industrial application. Here, we propose an ultrafast crystal growth process with low energy consumption and capability of producing crystals of excellent quality, and demonstrate that large-sized GaSe crystals with a lateral size of 0.5 to 1 cm can be obtained within a short period of 5 min. X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM) studies clearly indicate that the as-grown crystals have a good crystallinity. To further show the potential application of the resulting GaSe crystals, we fabricate the few-layer GaSe-based photodetector, which exhibits low dark current of 21 pA and fast response of 34 ms under 405 nm illumination. Our proposed technique for rapid crystal growth could be further extended to other metallenes with low-melting point, such as Bi-, Sn-, In-, Pb-based crystals, opening up a new avenue in fulfilling diverse potential optoelectronics applications of two-dimensional (2D) crystals.

Key challenges in the development of organic light-emitting transistors (OLETs) are blocking both scientific research and practical applications of these devices, e.g., the absence of high-mobility emissive organic semiconductor materials, low device efficiency, and color tunability. Here, we report a novel device configuration called the energy transfer organic light-emitting transistor (ET-OLET) that is intended to overcome these challenges. An organic fluorescent dye-doped polymethyl methacrylate (PMMA) layer is inserted below the conventional high-mobility organic semiconductor layer in a single-component OLET to separate the functions of the charge transport and light-emitting layers, thus making the challenge to essentially integrate the high mobility and emissive functions within a single organic semiconductor in a conventional OLET or multilayer OLET unnecessary. In this architecture, there is little change in mobility, but the external quantum efficiency (EQE) of the ET-OLET is more than six times that of the conventional OLET because of the efficient Förster resonance energy transfer, which avoids exciton-charge annihilation. In addition, the emission color can be tuned from blue to white to green-yellow using the source-drain and gate voltages. The proposed structure is promising for use with electrically pumped organic lasers.