Browsing by Author "Amresh Kumar Singh"

Now showing 1 - 2 of 2

One-Step Room Temperature Synthesis of Printable Carbon Quantum Dots Ink for Visual Encryption and High-Performance Photodetector
(John Wiley and Sons Inc, 2024) Baishali Thakurta; Sobhan Hazra; Alapan Samanta; Adnan Nasir; Amresh Kumar Singh; Deepak Maurya; Bama Charan Mondal; Anupam Giri; Bhola Nath Pal; Monalisa Pal
Carbon quantum dots (CQDs) have emerged as promising materials for optoelectronic applications and have garnered much interest as potential competitors to conventional inorganic or hybrid semiconductor quantum dots because of carbon's intrinsic merits of high stability, low cost, and environment-friendliness. The ability of easy formulation of functional ink of CQDs is necessary for the development of industrial-scale, reliable, inexpensive printing/coating processes, for its full exploitation in the ever-growing class of applications in sensors, optoelectronics, and energy storage and conversion. Here a facile one-step room-temperature synthesis of printable, fluorescent CQD ink is demonstrated. The as-synthesized fluorescent CQD ink is used for invisible fingerprint stamps, printing of micro-patterns, and soft lithographic patterning with a resolution down to 1.5 µm. This functional CQD ink is also used to fabricate a high-performance CQD-ZnO heterojunction ultraviolet (UV) photodetector with a photo-responsivity of 3.85 A W−1, detectivity of 6.78 × 1010 Jones, and an external quantum efficiency (EQE) of 15.3%. The enhanced device performance can be attributed to CQD's high photocurrent generation efficiency and rational combination of the asymmetric electrode materials. This work enables a high-temperature stable CQD fluorescent ink synthesis method to fulfill the processing requirements of printing and soft lithographic patterning for visual encryption and optoelectronics. © 2024 Wiley-VCH GmbH.
Wafer-scale synthesis of two-dimensional ultrathin films
(Royal Society of Chemistry, 2023) Amresh Kumar Singh; Baishali Thakurta; Anupam Giri; Monalisa Pal
Two-dimensional (2D) materials, consisting of atomically thin layered crystals, have attracted tremendous interest due to their outstanding intrinsic properties and diverse applications in electronics, optoelectronics, and catalysis. The large-scale growth of high-quality ultrathin 2D films and their utilization in the facile fabrication of devices, easily adoptable in industrial applications, have been extensively sought after during the last decade; however, it remains a challenge to achieve these goals. Herein, we introduce three key concepts: (i) the microwave assisted quick (∼1 min) synthesis of wafer-scale (6-inch) anisotropic conducting ultrathin (∼1 nm) amorphous carbon and 2D semiconducting metal chalcogenide atomically thin films, (ii) a polymer-assisted deposition process for the synthesis of wafer-scale (6-inch) 2D metal chalcogenide and pyrolyzed carbon thin films, and (iii) the surface diffusion and epitaxial self-planarization induced synthesis of wafer-scale (2-inch) single crystal 2D binary and large-grain 2D ferromagnetic ternary metal chalcogenide thin films. The proposed synthesis concepts can pave a new way for the manufacture of wafer-scale high quality 2D ultrathin films and their utilization in the facile fabrication of devices. © 2024 The Royal Society of Chemistry.