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Self-powered infrared detection using a graphene oxide film
摘要： The interaction between water and graphene oxide (GO), including water adsorption and desorption, have been widely used to demonstrate moisture-electric energy transformation (MEET). By taking advantage of water desorption stimulated by infrared (IR) light from a graphene oxide film with a gradient of oxygen-containing groups (O-group), a self-powered IR detection approach that can convert IR light into electric signals is demonstrated. The temperature sensitivity reaches 4.2 mK. With further optimization of the materials and structures, the performance of such self-powered IR detection can be further improved. The mechanism of the detection involving IR/thermal effect on the interaction between vapor molecules and solid materials also has potential applications in thermal detection, thermal energy conversion, and chemical sensing.
关键词： thermal sensitivity,graphene oxide,moisture-electric energy transformation,self-powered,infrared detection
更新于2025-09-23 15:19:57
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High Temperature Operation Limit Assessment for 4H-SiC Schottky Diode-based Extreme Temperature Sensors
摘要： We developed a simplified theoretical model for parameters calculation of diode temperature sensors (DTS) based on Schottky diodes (SD). The current flow mechanism of the diodes considered was dominated by over-barrier thermionic emission. Qualitative correlations between basic fundamental and electrophysical parameters of such DTS were established. The expressions for ultimate high-temperature parameters of the DTS were obtained. Theoretical results obtained were approved using test samples of DTS with Schottky contact Ni/n-SiC (4H). It was shown that physical high-temperature limit of operation of such a DTS (>1250 K) exceeded the values of commercial DTS based on Si, GaAs, AlGaAs p-n junctions. And the SD-based DTS itself demonstrated significantly lower energy consumption.
关键词： wide bandgap,thermal sensitivity,high temperature,Schottky diode,temperature sensor,semiconductor,thermal limit
更新于2025-09-09 09:28:46
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Optical temperature sensor based on Sm3+ emissions in a fluorotellurite glass
摘要： The temperature dependence of the visible luminescence of a fluorotellurite glass doped with 2.5 mol% of Sm3+ ions was studied in order to use it as a high temperature sensing probe. For this purpose, the emission intensities of the levels from 4G5/2 to 6HJ (J = 5/2, 7/2, 9/2, 11/2) transitions were measured in a temperature range from 300 up to 650 K. The changes in the emission profiles were calibrated by means of the fluorescence intensity ratio technique. The maximum temperature value obtained for the thermal sensibility was 640 K which is in the range of other matrix glasses. The calibration curve was done by fitting the intensity ratio between the different peak emissions. Finally, a schematic design for the Sm3+ optical temperature sensor is presented and the calculations of the sensitivity have been obtained. In addition, the fluorotellurite glass has been structural characterized by SEM-EDX, Raman Spectroscopy and XRD in order to infer the local environment of Sm3+ ions. Furthermore, the Judd-Ofelt parameters have been calculated from the absorption spectra and derived branching ratios and transition probabilities have been computed as well.
关键词： Material characterization,Sm3+,Thermal sensitivity,Fiber optical temperature sensor,Tellurite glass
更新于2025-09-04 15:30:14
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Electrochromic Switch Devices Mixing Small- and Large-Sized Upconverting Nanocrystals
摘要： The hasty progress in smart, portable, flexible, and transparent integrated electronics and optoelectronics is currently one of the driving forces in nanoscience and nanotechnology. A promising approach is the combination of transparent conducting electrode materials (e.g., silver nanowires, AgNWs) and upconverting nanoparticles (UCNPs). Here, electrochromic devices based on transparent nanocomposite films of poly(methyl methacrylate) and AgNWs covered by UCNPs of different sizes and compositions are developed. By combining the electrical control of the heat dissipation in AgNW networks with size-dependent thermal properties of UCNPs, tunable electrochromic transparent devices covering a broad range of the chromatic diagrams are fabricated. As illustrative examples, devices mixing large-sized (>70 nm) β-NaYF4:Yb,Ln and small-sized (<15 nm) NaGdF4:Yb,Ln@NaYF4 core@shell UCNPs (Ln = Tm, Er, Ce/Ho) are presented, permitting to monitor the temperature-dependent emission of the particles by the intensity ratio of the Er3+ 2H11/2 and 4S3/2 → 4I15/2 emission lines, while externally controlling the current flow in the AgNW network. Moreover, by defining a new thermometric parameter involving the intensity ratio of transitions of large- and small-sized UCNPs, a relative thermal sensitivity of 5.88% K?1 (at 339 K) is obtained, a sixfold improvement over the values reported so far.
关键词： electrochromic materials,upconverting nanocrystals,thermal sensitivity,transparent conducting electrode materials,silver nanowires
更新于2025-09-04 15:30:14