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A temperature-controlled synthesis process for ZnO nanoparticles (NPs) with the assist of oleylamine (OAm) has been demonstrated, and the ZnO NPs show bright fluorescence under ultraviolet illumination. In this process, zinc nitrate was firstly converted to zinc nitrate hydroxide (Zn5(OH)8(NO3)2) sheets with the assist of OAm, then the Zn5(OH)8(NO3)2 was decomposed into fluorescent ZnO NPs by increasing the ambient temperature. Furthermore, information encryption has been realized based on this process. For encryption, the encrypted information cannot be observed, while the encrypted information appears when they are proceeded in the temperature of 120 °C for about one minute. The results shown in this work provide a controllable way for the synthesis of ZnO NPs by adjusting the reaction temperature, and this may inspire wide applications of ZnO in information encryption. [ABSTRACT FROM AUTHOR]

The newly emerging metal halide perovskites have attracted considerable attention due to their exceptional optoelectronic properties. This upsurge was initially driven when the power conversion efficiency of perovskite-based photovoltaic devices exceeded 23%. Due to their optoelectronic properties, perovskite materials have also been used in light-emitting diodes, photodetectors, lasers, and memory devices. This study comprehensively discusses the recent progress of all-inorganic perovskite-based photodetectors, focusing on their structures, morphologies of their constituent materials, and diverse device architectures that improve the performance metrics of these photodetectors. A brief outlook, highlighting the main existing problems, possible solutions to these problems, and future development directions, is also provided herein. [ABSTRACT FROM AUTHOR]

ZnO quantum dots (QDs) as an eco-friendly and low-cost material has bright fluorescence, which makes it promising material for healthy lighting and displaying. However, the low fluorescence efficiency and poor stability of ZnO QDs impede their applications in lighting application. In this work, silica encapsulated ZnO QD-phosphors nanocomposites (ZSPN) have been prepared through a sol-gel synthesis process, where yellow-emitting ZnO QDs and blue-emitting BaMgAl10O17:Eu2+ are employed as the luminescence cores and silica as link between two luminescence materials. Tunable photoluminescence of ZSPN and the white light emission have been achieved through changing mass ratio of both of ZnO QDs and commercial phosphors. The PLQY of the ZSPN can reach 63.7% and they can maintain high luminous intensity even the ambient temperature up to 110 °C and after 35 h of UV irradiation. In addition, they can keep stable for 40 days. By coating the ZSPN phosphors onto a ultraviolet chip, WLEDs with luminous efficiency of 73.6 lm/W and the color coordinate, correlated color temperature, and color rendering index can reach (0.32, 0.34), 5580 K, and 87, respectively, indicating the bright prospect of the ZSPN phosphors used in healthy lighting. [ABSTRACT FROM AUTHOR]

Deep-ultraviolet (DUV) light-emitting devices (LEDs) have a variety of potential applications. Zinc-oxide-based materials, which have wide bandgap and large exciton binding energy, have potential applications in high-performance DUV LEDs. To realize such optoelectronic devices, the modulation of the bandgap is required. This has been demonstrated by the developments of MgZnO and BeZnO alloys for the larger bandgap materials. Many efforts have been made to obtain DUV LEDs, and promising successes have been achieved continuously. In this article, we review the recent progress of and problems encountered in the research of ZnO-based DUV LEDs. [ABSTRACT FROM AUTHOR]

Here, we report that nanodiamonds (NDs) exhibit blue fluorescence with an emission peak at around 400 nm. With increasing temperature, the peak energy of fluorescence was found to demonstrate a blue shift, possibly due to excited excitons populating higher-energy states, such as oxidation defect states. The intensity evolution of the fluorescence was attributed to a thermally activated process. Moreover, the bandwidth of fluorescence also increased because of exciton–phonon interactions and ionized impurity scattering. The above results indicate that the fluorescence of NDs could originate from radiative recombination through intrinsic transitions between highly localized π states. [ABSTRACT FROM AUTHOR]

In this study, we report quantum-dot light-emitting devices (QD-LEDs) using ammonia reduced graphene oxide (rGO) as a hole injection layer (HIL). Compared with pristine GO, QD-LEDs employing rGO as a HIL show higher maximum luminance (936 cd m−2 versus 699 cd m−2) and lower turn-on voltage (Vth, 5.0 V versus 7.5 V). The improved performance can be attributed to the synergistic effect of the improved conductivity (1.27 μS cm−1 versus 0.139 μS cm−1) and decreased work function (5.27 eV versus 5.40 eV) of the GO after the reduction process. The above results indicate that ammonia functionalized graphene may be a promising hole injection material for QD-LEDs. [ABSTRACT FROM AUTHOR]