Responsivity

About: Responsivity is a research topic. Over the lifetime, 9918 publications have been published within this topic receiving 186118 citations.

Efficiency enhancement of TiO2 self-powered UV photodetectors using a transparent Ag nanowire electrode

Abstract: A novel efficient way to realize high performance TiO2 self-powered UV photodetectors (PDs) with enhanced responsivity is proposed in this work. By constructing asymmetric electrodes consisting of a commercial mixed silver paste and two different forms of Ag nanostructures (nanofilms and nanowires) on the active layer of TiO2, respectively. Both PD devices exhibited attractive photovoltaic characteristics in a self-powered mode (at 0 V bias). Interestingly, the responsivity of the TiO2 UV PDs is found to be enhanced by 9 times at the wavelength of 350 nm without any power supply when the configuration of the Ag nanostructure electrode was changed from nanofilms to transparent nanowires. The enhanced photoelectric conversion efficiency is mainly attributed to a modified Schottky barrier through reducing hole traps and a higher light absorptivity through using a transparent electrode according to the experimental results and physical models based on the energy band theory. In addition, TiO2 UV PDs with a Ag nanowire electrode also exhibited excellent photoelectric properties in terms of a high linear dynamic range of 103.7 dB, a fast response speed (rise time of 2 ms and fall time of 41 ms), and excellent stability. The design solutions proposed here may provide additional opportunities for further development of Schottky junction-based self-powered UV PDs with high efficiencies.

Laser chemosensor with rapid responsivity and inherent memory based on a polymer of intrinsic microporosity.

Abstract: This work explores the use of a polymer of intrinsic microporosity (PIM-1) as the active layer within a laser sensor to detect nitroaromatic-based explosive vapors. We show successful detection of dinitrobenzene (DNB) by monitoring the real-time photoluminescence. We also show that PIM-1 has an inherent memory, so that it accumulates the analyte during exposure. In addition, the optical gain and refractive index of the polymer were studied by amplified spontaneous emission and variable-angle ellipsometry, respectively. A second-order distributed feedback PIM-1 laser sensor was fabricated and found to show an increase in laser threshold of 2.5 times and a reduction of the laser slope efficiency by 4.4 times after a 5-min exposure to the DNB vapor. For pumping at 2 times threshold, the lasing action was stopped within 30 s indicating that PIM-1 has a very fast responsivity and as such has a potential sensing ability for ultra-low-concentration explosives.

Broadband Ultraviolet Self-Powered Photodetector Constructed on Exfoliated β-Ga2O3/CuI Core-Shell Microwire Heterojunction with Superior Reliability.

Abstract: A heterojunction is an essential strategy for multispectral energy-conservation photodetection for its ability to separate photogenerated electron-hole pairs and tune the absorption edge by selecting semiconductors with appropriate bandgaps. A broadband ultraviolet (200-410 nm) self-powered photodetector is constructed on the exfoliated β-Ga2O3/CuI core-shell microwire heterostructure. Benefiting from the photovoltaic and photoconductive effects, our device performs an excellent ultraviolet (UV) discriminability with a UVC/visible rejection ratio (R225/R600) of 8.8 × 103 and a UVA/visible rejection ratio (R400/R600) of 2.7 × 102, and a self-powered photodetection with a responsivity of 8.46 mA/W, a detectivity of 7.75 × 1011 Jones, an on/off switching ratio of 4.0 × 103, and a raise/decay speed of 97.8/28.9 ms under UVC light. Even without encapsulation, the photodetector keeps a superior stability over ten months. The intrinsically physical insights of the device behaviors are investigated via energy band diagrams, and the charge carrier transfer characteristics of the β-Ga2O3/CuI interface are predicted by first principle calculation.