Sahu, Satyajit

2024, Dibyajyoti Saikia, Chayan Das, Anupam Chetia, Atanu Betal, Sahu, Satyajit

All inorganic CsPbX3 perovskites (X = Br and I) are excellent candidates for stable and efficient perovskite solar cells (PSCs). Among them, CsPbIBr2 demonstrated the most balanced characteristics in terms of band gap and stability. Nevertheless, the power conversion efficiency (PCE) of CsPbIBr2-based solar cells is still far from that of Hybrid PSCs, and more research is required in this aspect. Herein, DFT and SCAPS-1D frameworks are employed to explore the optimized device configurations of CsPbIBr2 PSCs. DFT is used to explore the structural and optoelectronic characteristics of CsPbIBr2, while SCAPS-1D is employed to examine various device structures of CsPbIBr2-based PSCs. The band structure demonstrated the direct band gap nature of CsPbIBr2 with a band gap of 2.12 eV. Moreover, we have used TiO2, SnO2, ZnO, WS2, IGZO, CeO2, In2S3, and CdS as ETLs, and Cu2O, CuI, MoO3, NiO, CuSCN, CuSbS2, CBTS, CFTS, and CuO as HTLs for identifying the best ETL/CsPbIBr2/HTL configurations. Among 72 device combinations, eight sets of PSCs are identified as the most efficient configurations. In addition, the influence of various parameters like the thickness of various layers, doping concentration, perovskite defect density, ETLs and interfaces, series resistances, shunt resistances, and temperature on device performance have been comprehensively studied. The results demonstrate Cu2O as the best HTL for CsPbIBr2 with each ETL, and PSC with device structure ITO/WS2/CsPbIBr2/Cu2O/C exhibited the highest PCE of 16.53%. This comprehensive investigation will provide new path for the development of highly efficient all-inorganic CsPbIBr2 solar cells.

2024, Mubashir Mushtaq Ganaie, Amit Kumar, Amit K. Shringi, Sahu, Satyajit, Michael Saliba, Kumar, Mahesh

In conventional designs, sensory systems are segregated from memory and computing units. The conversion and transmission of data from analog sensing domains to digital storage result in inefficient power utilization and increased latency. Here, a multifunctional memristor capable of detecting gamma radiation while also serving as a data storage device and an artificial synapse is reported. Large-scale integration of oxide-based memristors for artificial neural networks faces major challenges due to the sneak-path current issue in crossbar arrays. Consequently, material combinations and fabrication variables significantly shape nanoscale processes, which are essential in determining resistive switching properties and functionalities. Resistive switching in AlFeO3 is studied using different electrode materials (silver (Ag), gold (Au), chromium (Cr), fluorine-doped tin oxide, and silicon), embedding metal (Ag, Au) nanocrystals to engineer a class of tunable memories capable of functioning as selector, memory, artificial synapse, and dosimeter. Techniques like electrode engineering, nanocrystal seeding, and temperature-dependent thin film deposition are employed to tune resistive and threshold switching functionalities. Accessing different functionalities requires changing the electrode materials or changing the synthesis conditions of the AlFeO3 resistive switching layer and are not interconvertible in the same device simultaneously. The devices emulate critical neural functions and demonstrate interconversion dynamics between short-term and long-term plasticity.

2024, Chayan Das, Suresh Kumar, Neha V. Dambhare, Kumar, Mahesh, Arup K. Rath, Sahu, Satyajit

Semiconducting 2D transition metal dichalcogenides (TMDC) became very popular in photodetection due to their high mobility and high rate of generating electron and hole pairs. Over the past decade, MoS2 and WS2 became the most popular TMDC for several applications. On the other hand, due to the complex synthesis process compared to MoS2 and WS2, SnS2 became a less popular 2D material for photodetection. We synthesized vertically aligned SnS2 flakes by a chemical vapor deposition (CVD) process with three temperature zones with controlled argon (Ar) gas flow. Pristine SnS2-based devices are not very suitable for photodetection applications because of their low photo-to-dark current ratio (Iph/Idark), high response time, and low stability. So, they need to be decorated with oppositely doped materials. We decorated pristine SnS2-based devices with rGO nanoparticles, which significantly increased the device’s performance. We found a high responsivity (R) of 1.33 A/W, detectivity (D) of 6.95 × 1011 Jones, Iph/Idark of 102, and a rise time of 0.241 ms (fall time of 1.318 ms) with the rGO decorated SnS2-based device.

2024, Chayan Das, Suresh Kumar, Neha V. Dambhare, Mahesh Kumar, Arup K. Rath, Satyajit Sahu

Semiconducting 2D transition metal dichalcogenides (TMDC) became very popular in photodetection due to their high mobility and high rate of generating electron and hole pairs. Over the past decade, MoS2 and WS2 became the most popular TMDC for several applications. On the other hand, due to the complex synthesis process compared to MoS2 and WS2, SnS2 became a less popular 2D material for photodetection. We synthesized vertically aligned SnS2 flakes by a chemical vapor deposition (CVD) process with three temperature zones with controlled argon (Ar) gas flow. Pristine SnS2-based devices are not very suitable for photodetection applications because of their low photo-to-dark current ratio (Iph/Idark), high response time, and low stability. So, they need to be decorated with oppositely doped materials. We decorated pristine SnS2-based devices with rGO nanoparticles, which significantly increased the device’s performance. We found a high responsivity (R) of 1.33 A/W, detectivity (D) of 6.95 × 1011 Jones, Iph/Idark of 102, and a rise time of 0.241 ms (fall time of 1.318 ms) with the rGO decorated SnS2-based device.