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Inorganic semiconductor-based photodetectors have been suffering from slow response speeds, which are caused by the persistent photoconductivity of semiconductor materials. For realizing high speed optoelectronic devices, the organometal halide perovskite thin films were applied onto the interdigitated (IDT) patterned Au electrodes, and symmetrical structured photoconductive detectors were achieved. The detectors were sensitive to the incident light signals, and the photocurrents of the devices were 2-3 orders of magnitude higher than dark currents. The responsivities of the devices could reach up to 55 mA W(1-). Most importantly, the detectors have a fast response time of less than 20 μs. The light and bias induced dipole rearrangement in organometal perovskite thin films has resulted in the instability of photocurrents, and Ag nanowires could quicken the process of dipole alignment and stabilize the photocurrents of the devices.

Self-powered photodetectors (SPPDs) have attracted lots of attention due to their various advantages including no external power sources, high-sensitivity, fast response speed, and so on. This study reports the fabrication and characterization results of CsPbBr 3 microcrystals (MCs) grown by chemical vapor deposition (CVD) method, and the SPPDs have been fabricated on the basis of the CsPbBr 3 MCs layer with the sandwich structure of GaN/CsPbBr 3 MCs/ZnO. Such designed SPPD shows the detectivity (D*) of 10 14 Jones, on/off ratio of up to 10 5 , peak responsivity (R) of 89.5 mA/W, and enhanced stability at the incident wavelength of 540 nm. The photodetector enables the fast photoresponse speed of 100 μs rise time and 140 μs decay time. The performances of the SPPD are comparable to the best ones ever reported for CsPbBr 3 based PDs but do not need external power supplies, which mainly benefit from the low trap density, long carrier diffusion of high quality CsPbBr 3 MCs film, and the built-in electric fields in the sandwich structure of GaN/CsPbBr 3 /ZnO layers.

Carbon dot (CD)-NaCl hybrid crystals are obtained by incorporating the CDs into NaCl matrix through a simple process. The embedded CDs have added the luminescence centers into NaCl, and as a result, the hybrid crystals present the fluorescence centered at 510 nm under the illumination of 365 nm light. Meanwhile, the phosphorescence with an average lifetime of 314 ms is achieved after the 365 nm light was turned off. Furthermore, optical gain and lasing phenomenon has been observed from hybrid crystals. When the pump power is low, a weak spontaneous emission can be observed from the hybrid crystal, whereas the lasing action was observed under high pump power. The lasing threshold is found to be 0.08 mW and corresponding Q factor is calculated to be 447. The tiny cubic crystal in hybrid crystals offers the whispering gallery mode (WGM) resonant cavity for lasing emission. That has provided a new approach for realizing lasing materials.

An Au decorated WO 3 photoelectrode was successfully synthesized and the photoelectrochemical properties were studied. Due to the enhanced light absorption, higher carrier density and lower transport resistance resulting from the surface plasmon resonance of Au nanoparticles, an improved photocurrent density of 0.44 mA cm À2 at 1 V vs. Ag/AgCl in 0.5 M NaSO 4 under irradiation of 100 mW cm À2 was achieved, demonstrating about quadruple than that of a WO 3 photoelectrode.

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Blue luminescent carbon dots (CDs) were synthesized by the hydrothermal method. Blue-shifts of the maximum emission wavelength from 480 to 443 nm were observed when the concentration of CD solution decreased. The photoluminescence (PL) spectra of CDs at low concentration showed an excitation-independent behaviour, which is very different from the previous reports. Two different emitting mechanisms might work: the intrinsic luminescence from sp2-carbon networks can be responsible for the shorter wavelength part of emission (excitation-independent) at low concentration and the high polarity of nanosized clusters led to the excitation-dependent behaviour of the longer wavelength part at high concentration of CD solution. The photophysical property and concentration-dependent behaviour of the CDs offered new insights into CDs from the viewpoints of both experiments and mechanisms, which will promote diverse potential applications of CDs in the near future.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-017-2137-2) contains supplementary material, which is available to authorized users.

In this paper, we report the design, synthesis, and dielectric properties of novel high-k and cross-linked polymer dielectric films used in low-threshold-voltage organic thin-film transistors (OTFTs). The novel polymer films are readily fabricated by spin coating followed by curing at 160 °C. These films exhibit excellent insulating properties, smooth surface, and high dielectric constant (7.2 and 6.8, respectively). The bottom-gate top-contact para-sexiphenyl (p-6P)/ vanadyl-phthalocyanine (VOPc) OTFTs with these 10 polymer films as the dielectric layer exhibit excellent performance in terms of threshold voltage (−3 and +3 V, respectively), charge carrier mobility (0.8 and 0.5 cm 2 /Vs, respectively), on/off current ratio > 10 4 , and ultralow leakage.