Due to its excellent physical and chemical properties, the halide all-inorganic CsPbX 3 (X = Cl, Br, I) perovskite semiconductors are intensively studied and the applications are penetrating many fields such as solar cells, [1][2][3][4][5][6] light emitting diodes, [7][8][9][10] lasers, [11][12][13] chemical sensors, [14][15][16] catalysis, [17][18][19] photo/X-ray/γ-ray detectors, [20][21][22][23][24][25][26][27] transistors, [28][29][30] and computing. [31,32] Driven by this trend, various types of perovskite based heterojunctions, for example, perovskite-metal, perovskite-semiconductor, or perovskite-insulator heterojunctions have been developed and All-Inorganic perovskite CsPbX 3 (X = Cl, Br, I) quantum dots (QDs) have attracted tremendous attention in the past few years for their appealing performance in optoelectronic applications. Major properties of CsPbX 3 QDs include the positive photoconductivity (PPC) and the defect tolerance of the in-band trap states. Here it is reported that when hybridizing CsPbX 3 QDs with indium tin oxide (ITO) nanocrystals to form CsPbX 3 -ITO nano-heterojunctions (NHJs), a voltage tuned photoresponse-from PPC to negative photoconductivity (NPC) transform-is achieved in lateral drain-source structured ITO/CsPbX 3 -ITO-NHJs/ITO devices. A model combining exciton, charge separation, transport, and most critical the voltage driven electron filling of the in-band trap states with drain-source voltage (V DS ) above a threshold, is proposed to understand this unusual PPC-NPC transform mechanism, which is different from that of any known nanomaterial system. This finding exhibits potentials for developing devices such as photodetectors, optoelectronic switches, and memories.

As a narrow band semiconductor at room temperature and a metallic material above ∼68 °C, functional VO2 films are widely investigated for smart windows, whereas their potential for ultraviolet–visible–infrared (UV–vis–IR) broad spectral photodetectors has not been efficiently studied. In this report, photodetectors based on VO2–ZnO nanocrystal composite films were prepared by nanocrystal-mist (NC-mist) deposition. An enhanced photodetection switching ratio was achieved covering the ultraviolet to infrared wavelength. Due to the synergetic effect of nanosize, surface, phase transition, percolation threshold, and the band structure of the heterojunction, the transfer and transport of photogenerated carriers modulate the device performance. This study probes new chances of applying VO2-semiconductor-based nanocomposites for broad spectral photodetectors.