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Metal phosphorus trichalcogenides (MPX3) have attracted extensive attention as promising two-dimensional (2D) layered materials in future electronic and optoelectronic devices. Here, for the first time, few-layer In4/3P2Se6 nanoflakes have been successfully exfoliated from home-made high-quality single crystals. The In4/3P2Se6 crystal belongs to the R3 space group, and possesses a weak van der Waals force between the adjacent layers and a direct bandgap of 1.99 eV. Furthermore, the In4/3P2Se6-based photodetectors show high performances in the visible light region, such as a high responsivity (R) of 4.93 A·W-1, a high external quantum efficiency (EQE) of 1509% and a fast response time, as low as 2.1 ms. In particular, the high detectivity (D) of the devices can reach up to 4.3 × 1013 Jones (light ON/OFF ratio ≈104) under illumination from a 405 nm light at a bias voltage of 1 V, which is favoured by the ultralow dark current (∼100 fA). These excellent performances pave the way for the implementation of In4/3P2Se6 nanoflakes as promising candidates for future optoelectronic detection applications.

Ternary alloyed colloidal quantum dots (QDs) have attracted more and more attention due to their distinct optoelectronic properties that may not be present in their parent binary systems, and they have shown great potential application in optoelectronic devices. In this work, ternary alloyed CdSexTe1-x colloidal QDs were successfully prepared via a simple and facile one-pot hydrothermal technique, and the composition and bandgap of CdSexTe1-x can be tuned by manipulating the feed molar ratio of Se/Te. During the hydrothermal reaction process, the CdSexTe1-x QDs were simultaneously in-situ assembled onto mesoporous TiO2 film due to the use of bifunctional capping agent (thioglycolic acid), so this strategy combines colloidal QDs synthesis and adsorption of QDs within TiO2 in a single step, and thus high loading and uniform distribution of CdSexTe1-x sensitizer within TiO2 matrix could be achieved. The photovoltaic properties of TiO2/CdSexTe1-x photoanode with different composition were investigated, and the best power conversion efficiency of 3.23% under one sun illumination (AM 1.5G, 100 mW cm−2) was obtained for the CdSexTe1-x sensitizer synthesized with Se:Te = 2:2. These results show the potential application of hydrothermal method and alloyed CdSexTe1-x QDs in preparing high-performance QDSSC in the future.

In this work, copper selenide (Cu

High performance photodetectors based on van der Waals heterostructures (vdWHs) are crucial to developing micro-nano-optoelectronic devices. However, reports show that it is difficult to balance fast response and high sensitivity. In this work, we design a photovoltaic field-effect photodiode (PVFED) based on the WSe2/MoS2/WSe2 double vdWHs, where the photovoltage that originated from one vdWH modulates the optoelectronic characteristics of another vdWH. The proposed photodiode exhibits an excellent self-powered ability with a high responsivity of 715 mA·W-1 and fast response time of 45 μs. This work demonstrates an efficient method that optimizes the photoelectric performance of vdWH by introducing the photovoltaic field effect.

In this study, PbS thin films are deposited on FTO substrate via a rapid and facile microwave-assisted chemical bath deposition (MACBD) and then used directly as the counter electrodes (CEs) for CdS/CdSe quantum dots co-sensitized ZnO nanorods array solar cells (QDSSC). The resultant PbS CEs show good uniformity, strong adhesion to the FTO and superior electrocatalytic activity for the reduction of polysulfide electrolyte compared to the PbS CEs prepared with conventional CBD method. The combination of ZnO/CdS/CdSe photoanode with the optimum PbS CE shows appreciated power conversion efficiency (PCE) of 4.85%. The augmented photovoltaic performance can be attributed to its high electrocatalytic activity for polysulfide reduction in QDSSC, which results in a low charge transfer resistance at the interface of CE/electrolyte. The results demonstrate the potential application of this MACBD method in fabricating efficient metal sulfide counter electrode for QDSSC.

Metal phosphorus trichalcogenides (MPX

In this work, copper selenide (Cu2−x Se) thin films were grown on FTO conductive glass substrates using a facile microwave-assisted hydrothermal method. The effects of synthesis parameters such as precursor components and deposition time on the stoichiometry and morphology of the synthesized films were systematically investigated through different techniques including XRD, SEM, and AFM. In order to evaluate the electrochemical catalytic performance of the synthesized copper selenide in electrolyte containing the sulfide/polysulfide redox couple, we assembled liquid-junction quantum dots-sensitized solar cells (QDSSC) using the synthesized copper selenide thin films as counter electrodes and CdSe quantum dots-sensitized mesoporous TiO2 as photoanodes. Under the illumination of one Sun (100 mW cm−2), the QDSSC assembled with the optimal copper selenide CEs (Cu:Se = 1:1) exhibited a power conversion efficiency of 2.07%, which is much higher than that of traditional Pt counter electrode (0.76%).

Engineering of TiO

Engineering of TiO2 photoanode is an important strategy for increasing the photovoltaic conversion efficiency of quantum dots-sensitized solar cells (QDSSCs). In this work, three-dimensional ordered macroporous (3DOM) TiO2 films are fabricated by the controlled infiltrating-calcination method using the close-packed polystyrene spheres colloidal crystals as templates. The as-prepared macroporous TiO2 films are then applied as the photoanode in colloidal CdSe QDSSCs. This structure not only facilitates the penetration of thioglycolic acid capped CdSe QDs, and thus achieving a high coverage of the internal surface with QDs sensitizer, but also exhibits a photonic band gap with tunable positions, which could enhance the light absorption. As a result, the liquid-junction QDSSCs assembled with the CdSe sensitized 3DOM TiO2 yields a power conversion efficiency of 3.60% under solar illumination of 100 mW cm-2, and this value is much higher than that of the device using nanoporous TiO2 photoanode (1.82%). Our results indicate that the 3DOM TiO2 is a promising candidate for the construction of high-efficiency QDSSCs.