Low-temperature ionic layer adsorption and reaction grown anatase TiO 2 nanocrystalline films for efficient perovskite solar cell and gas sensor applications

A low-temperature (90 °C) and directly grown anatase titanium dioxide (TiO2) nanocrystalline film using successive ionic layer adsorption and reaction (SILAR) for perovskite solar cell and gas sensor applications. TiO2 nanocrystalline electron transfer layer (ETL) improves the power conversion efficiency (PCE) of perovskite solar cells due to faster charge transport kinetics as well as slower charge recombination process. The optimized TiO2 nanocrystalline ETL (15 L) demonstrates as high as ~10% PCE with a short circuit current density of 18.0 mA/cm2, open circuit voltage of 0.81 V and fill factor of 66.3% in perovskite solar cells. Furthermore, room-temperature ammonia sensing characteristics of TiO2 nanocrystalline film (25 L) were  demonstrated for various concentration levels of ammonia in dry air conditions. A high room-temperature response of 80% was achieved at 100 ppm of ammonia with rapid response and recovery signatures of 30 and 85 s, and nearly fifteen days stability, respectively. The response of the sensor to other gases such as formaldehyde, petrol, ethanol acetone, and ammonia etc, indicated a high selectivity towards volatile organic compounds of ammonia gas. The room temperature operation, with high selectivity, repeatability and fast transition times, suggests potentially useful in flexible and cost-effective production in optoelectrochemical device technology

Gold sensitized sprayed SnO2 nanostructured film for enhanced LPG sensing

We report LPG sensing of gold (Au)-sensitized SnO2 nanostructured film fabricated by an easy spray pyrolysis deposition method whose surface morphology is confirmed by field-emission scanning electron microscopy and atomic force microscopy images and structure by X-ray diffraction pattern. Energy dispersive X-ray spectrometer analysis has carried out for finding elemental composition. The SnO2 film is uniform and consists of spherical particles of ∼10nm. The highest gas response observed at 780ppm LPG concentration for pristine SnO2 is 28%, at operating temperature 623K, which is greatly improved on Au sensitization up to 57% with 60s rapid response time at 598K operating temperature. The high gas response is due to electronic effect and catalytic spill-over effect of Au sensitization. The improved sensing mechanism has throughly been explored

Natural carbonized sugar as a low-temperature ammonia sensor material: experimental, theoretical and computational studies

Carbonized sugar (CS) has been synthesized via microwave-assisted carbonization of market-quality tabletop sugar bearing in mind the advantages of this synthesis method, such as being useful, cost-effective, and eco-friendly. The as-prepared CS has been characterized for its morphology, phase purity, type of porosity, pore-size distribution, and so on. The gas-sensing properties of CS for various oxidizing and reducing gases are demonstrated at ambient temperature, where we observe good selectivity toward liquid ammonia among other gases. The highest ammonia response (50%) of a CS-based sensor was noted at 80 °C for 100 ppm concentration. The response and recovery times of the CS sensor are 180 and 216 s, respectively. This unveiling ammonia-sensing study is explored through a plausible theoretical mechanism, which is further well-supported by computational modeling performed using density function theory. The effect of relative humidity on the CS sensor has also been studied at ambient temperature, which demonstrated that the minimum and maximum (20–100%) relative humidity values revealed 16 and 62% response, respectively

Hybrid ZnO Flowers-Rods Nanostructure for Improved Photodetection Compared to Standalone Flowers and Rods

Different Zinc Oxide (ZnO) morphologies have been used to improve photodetector efficiencies for optoelectronic applications. Herein, we present the very novel hybrid ZnO flower-rod (HZFR) morphology, to improve photodetector response and efficiency when compared to the prevalently used ZnO nanorods (NRs) and ZnO nanoflowers (NFs). The HZFR was fabricated via sol-gel microwave-assisted hydrothermal methods. HZFR achieves the benefits of both NFs, by trapping a greater amount of UV light for the generation of e-h pairs, and NRs, by effectively transporting the generated e-h pairs to the channel. The fabricated photosensors were characterized with scanning electron microscopy, X-ray diffraction, photoluminescence, and a Keithley 4200A-SCS parameter analyzer for their morphology, structural characteristics, optical performance, and electrical characteristics, respectively. The transient current response, current-voltage characteristics, and responsivity measurements were set as a benchmark of success to compare the sensor response of the three different morphologies. It was found that the novel HZFR showed the best UV sensor performance with the fastest response time (~7 s), the highest on-off ratio (52), and the best responsivity (126 A/W) when compared to the NRs and NFs. Hence, it was inferred that the HZFR morphology would be a great addition to the ZnO family for photodetector applications

Gold sensitized sprayed SnO2 nanostructured film for enhanced LPG sensing

We report LPG sensing of gold (Au)-sensitized SnO2 nanostructured film fabricated by an easy spray pyrolysis deposition method whose surface morphology is confirmed by field-emission scanning electron microscopy and atomic force microscopy images and structure by X-ray diffraction pattern. Energy dispersive X-ray spectrometer analysis has carried out for finding elemental composition. The SnO2 film is uniform and consists of spherical particles of ∼10nm. The highest gas response observed at 780ppm LPG concentration for pristine SnO2 is 28%, at operating temperature 623K, which is greatly improved on Au sensitization up to 57% with 60s rapid response time at 598K operating temperature. The high gas response is due to electronic effect and catalytic spill-over effect of Au sensitization. The improved sensing mechanism has throughly been explored