Amit Kumar Shringi

Bio: Amit Kumar Shringi is an academic researcher from Indian Institute of Technology, Jodhpur. The author has contributed to research in topics: Materials science & Irradiation. The author has an hindex of 1, co-authored 2 publications receiving 5 citations.

High Performance Flexible Organic Field-Effect Transistors with Barium Strontium Titanate Gate Dielectric Deposited at Room Temperature

Abstract: Reducing the operating voltage and processing temperature are the crucial factors in the progression of organic field-effect transistors (OFETs) in flexible portable applications. Here, we have dem...

RF sputtered CuO anchored SnO2 for H2S gas sensor

Abstract: To achieve good living standards, it is critical to make high-performance toxic gas sensing devices for public safety, environmental pollutant control, industrial operations, and other applications. For this purpose, we demonstrate CuO anchored SnO2 nanostructures for H2S gas sensors. The selectivity was improved by anchoring with CuO for a total 60 s duration at four equal consecutive cycles to achieve good selectivity towards H2S molecules. The pristine CuO shows instability and metallic behaviour when it is exposed to H2S for a longer time. Furthermore, the proposed gas sensor shows good selectivity toward H2S as compared to other gases H2, NO2, CO2, and NH3. The sensing response was measured at around 69 % at the optimal operating temperature of 150 °C. It is observed that CuS formation has better selectivity as compared to pristine SnO2 and a slight improvement in sensitivity is observed. As a result, a promising strategy for designing and producing good-performance H2S gas sensors would be to CuO anchor on SnO2 nanostructures. The proposed sensors may be integrated with IoT platforms and used for the detection of H2S in the sewer line and leak detection in the petroleum industry.

MoS₂ Decorated α-Fe₂O₃ Nanostructures for Efficient NO₂ Gas Sensor

Abstract: Over the past few decades, metal oxide-based thin-film sensors have been widely studied and commercialized for gas sensing applications, but their poor sensing response and high-temperature operation (300 °C) are the issues to be addressed. Here, we demonstrate the molybdenum disulfide (MoS2) decorated $\alpha $ -Fe2O3 thin-film-based NO2 gas sensor. The $\alpha $ -Fe2O3 thin film was deposited on silicon substrate using the RF magnetron sputtering technique at 600 °C substrate temperature. The $\alpha $ -Fe2O3 thin films were characterized using an X-ray diffractometer and a scanning electron microscope for structural and morphological characterizations. Furthermore, we decorated the Fe2O3 thin film using hydrothermally synthesized MoS2 nanoparticles dispersed in ethanol via the drop-casting method to increase the response toward NO2 gas. The MoS2 decorated sensor shows a fast gas detection with the improved response of ( $\Delta \text{R}/\text{R}_{a}$ %) of ~69% at 150 °C for 100ppm of NO2 gas, which is 68% higher compared to the pristine sample (~42%). The sensor shows a fast response time of ~34 s and a moderate recovery time of ~95 s. The decoration of MoS2 nanoparticles has increased the surface-to-volume ratio and active sites and hence increased the number of gas molecules that can react with the surface of the sample. The sensor shows high sensitivity and selectivity toward NO2 due to increased holes and reduced barrier height in MoS2/ $\alpha $ -Fe2O3 p-p heterojunctions.

Gamma Radiation Detection Response of Pt/PZT/SRO Based Capacitor for Dosimetry Application

Abstract: Radiation induced changes in the electrical properties of PbZrTiO3 (PZT) thin films have been studied for dosimetry application. The radiation detection was based on radiation induced changes in the electrical properties under the influence of gamma radiation. Epitaxial heterostructure of ferroelectric PbZr0.52 Ti0.48O3 (001)/SrRuO3 (SRO) were grown on single crystal SrTiO3 (001) substrates by pulsed laser deposition and platinum (Pt) electrode was deposited on top of the PZT film. The maximum capacitance of the heteroepitaxial capacitor devices was $\approx ~25$ pF with a corresponding small leakage current. The effect of gamma ( $\gamma $ -ray) irradiation on the intrinsic electrical behavior of the Lead Zirconate Titanate (PZT) capacitor devices were explored in form of the current–voltage (I–V) and capacitance–voltage (C–V) properties. The PZT devices were exposed to a 60Co Gamma source with 2.8 kGy/h dose rate from 0 kGy to 400 kGy doses. Gamma radiation induced broadening was observed in full width half maxima (FWHM) of the x-ray diffraction (00l) peak with the increasing gamma doses. All devices showed a consistence changes in conductance and capacitance with increasing gamma doses. The results demonstrated linear relationship in electrical response of PZT thin-film capacitors as a function of gamma doses. The device showed significant changes in the values of current and capacitance with the increase in dose up to 400 kGy and are therefore suitable for high-dose dosimetry applications.

The Atomic Nucleus

Abstract: Elementary Nuclear Theory By Prof. Hans A. Bethe and Prof. Philip Morrison. Second edition. Pp. xi + 274. (New York: John Wiley and Sons, Inc.; London: Chapman and Hall, Ltd., 1956.) 50s. net.

Flexible organic solar cells: Materials, large-area fabrication techniques and potential applications

Abstract: Organic solar cells (OSCs) that converted sunlight into electricity have obtained numerous progress in the past two decades. With the efforts of developing new conjugated materials, the power conversion efficiencies (PCEs) of OSCs have realized over 18%, which are comparable with other types of solar cells. These great achievements enable OSCs to arrive at the key period toward industrial application. Flexibility is the main characteristic of OSCs, which endows OSCs to be applied into special fields. In this review, we will provide an overview about the research progress of flexible OSCs (F-OSCs), from the aspect of materials (including flexible electrodes, interfacial layers and photoactive layers), large-area fabrication techniques and potential applications. These advancements enable F-OSCs to achieve PCEs over 15% with high stability, and we will also discuss the problems in F-OSCs. We hope that with this review, more studies from the academia and industrial community will be involved into F-OSCs, especially focusing on new materials toward application in the future.

Transport in Twisted Crystalline Charge Transfer Complexes

Abstract: Many crystals grow as banded spherulites from the melt with an optical rhythm indicative of helicoidal twisting. In this work, 23 of 41 charge transfer complexes (CTCs) are grown with twisted morphologies. As a group, CTCs more commonly twist (56%) than molecular crystals arbitrarily chosen in our previous research (31%). To analyze the effect of twisting on charge transport, three tetracyanoethylene-based CTCs with phenanthrene (PhT), pyrene (PyT), and perylene are characterized. PhT and PyT are subject to mobility measurements using organic field-effect transistors. The mobilities for twisted crystals are around three times higher than for crystals with no ostensible optical modulation, which are effectively straight. The differences in mobilities of straight and twisted crystals are considered computationally based on density functional theory. Straight crystal models built from crystallographic information files are calculated and present anisotropic hole and electron transport. For twisted crystal models, adjacent layers in the supercell are rotated by 0.01° around experimentally determined twisting directions. The modified transfer integrals lead to a slight increase (up to 25%) in the calculated mobilities of twisted crystals. Comparisons of model calculations on individual fibrils and measurements of ensembles of fibrils indicate that interfaces between single crystals are likely consequential.

Charge Transport in Twisted Organic Semiconductor Crystals of Modulated Pitch

Abstract: Many molecular crystals (approximately one third) grow as twisted, helicoidal ribbons from the melt, and this preponderance is even higher in restricted classes of materials, for instance, charge‐transfer complexes. Previously, twisted crystallites of such complexes present an increase in carrier mobilities. Here, the effect of twisting on charge mobility is better analyzed for a monocomponent organic semiconductor, 2,5‐bis(3‐dodecyl‐2‐thienyl)‐thiazolo[5,4‐d]thiazole (BDT), that forms twisted crystals with varied helicoidal pitches and makes possible a correlation of twist strength with carrier mobility. Films are analyzed by X‐ray scattering and Mueller matrix polarimetry to characterize the microscale organization of the polycrystalline ensembles. Carrier mobilities of organic field‐effect transistors are five times higher when the crystals are grown with the smallest pitches (most twisted), compared to those with the largest pitches, along the fiber elongation direction. A tenfold increase is observed along the perpendicular direction. Simulation of electrical potential based on scanning electron microscopy images and density functional theory suggests that the twisting‐enhanced mobility is mainly controlled by the fiber organization in the film. A greater number of tightly packed twisted fibers separated by numerous smaller gaps permit better charge transport over the film surface compared to fewer big crystallites separated by larger gaps.

Multifunctional Flexible Organic Transistors with a High-k/Natural Protein Bilayer Gate Dielectric for Circuit and Sensing Applications

Abstract: Organic field-effect transistors (OFETs) have opened up new possibilities as key elements for skinlike intelligent systems, due to the capability of possessing multiple functionalities. Here, multifunctional OFET devices based on gelatin, a natural biopolymer gate dielectric, and TIPS-pentacene as an organic semiconductor are extensively explored. Gelatin is combined with a thin high-k HfO2 dielectric layer deposited by atomic layer deposition (ALD) to achieve a low leakage current and low-voltage operation. The natural biopolymer offers a better semiconductor:dielectric interface, leading to better charge conduction in the devices, along with an enhancement of sensing capabilities giving additional functionality. These fabricated flexible OFET devices exhibit excellent electrical characteristics with a high field-effect mobility reaching over 2 cm2/(V s) (extracted with Ci at 1 kHz), a low subthreshold swing (SS) of ∼200 mV/dec, and a high current on–off (Ion/Ioff) ratio at a low operating voltage of −5 V with excellent electrical and mechanical stability. Moreover, circuit and multiparameter sensing capabilities for visible and UV light, as well as for humidity and breath rate, have been successfully demonstrated for these devices. Our results indicate that these multifunctional OFET devices can open up a plethora of opportunities for practical applications such as real-time health and environmental monitoring.