Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
4 results
Search Results
Item A tale of two organic small molecular hole transporting materials: Showing same extended shelf-life but very different efficiency of inverted MAPbI3 perovskite solar cells(Elsevier B.V., 2022) Kakekochi, V.; Kuo, D.-W.; Chen, C.-T.; Wolcan, E.; Chen, C.-T.; Udayakumar, U.K.This paper mainly discusses the structure-property relationship of two donor-acceptor-donor (D–π–A–π–D) type dopant-free hole transporting materials (HTMs) (TPA-TPy and TPA-Py-PTZ) comprising primarily of 2,4,6-trisubstituted pyridine as the acceptor core and 4,4′-dimethoxytriphenylamine as the peripheral donor groups and their use in p-i-n perovskite solar cells (PVSCs). Compared to inferior TPA-Py-PTZ, TPA-TPy has a superior hole extraction and hole transport at the HTM/perovskite interface. The pinhole-free, smooth and dense, fully covered and well-crystallized MAPbI3 perovskite layer on TPA-TPy reduces the carrier recombination and substantially improves the short circuit current density (JSC), open circuit voltage (VOC), and the fill-factor (FF) of MAPbI3 PVSCs. The PVSC employing TPA-TPy as HTM exhibits a power conversion efficiency (PCE) of 15.33% with a JSC of 23.69 mA cm−2, a VOC of 0.95 V, and a FF of 68.10%. Especially, both TPA-TPy and TPA-Py-PTZ PVSCs exhibit a better moisture stability than that of NiOx PVSCs. It is because of the hydrophobic nature of TPA-TPy and TPA-Py-PTZ, which enables the formation of MAPbI3 perovskite layer having a larger grain-size, a less grain boundary, and a less infiltration of moisture. © 2022 Elsevier B.V.Item New Carbazole-Based Sensitizers for p-Type DSSCs: Impact of the Position of Acceptor Units on Device Performance(American Chemical Society, 2022) Keremane, K.S.; Pellegrin, Y.; Planchat, A.; Jacquemin, D.; Odobel, F.; Vasudeva Adhikari, A.V.We report the design, synthesis, and characterization of two new carbazole-based organic dyes PC1-2as potential sensitizers for NiO-based p-type dye-sensitized solar cells (p-DSSCs). The D-A-π-A' configured PC1dye comprises a thienyl unit as a π-spacer and a malononitrile as an end-capping acceptor unit, whereas in PC2the cyanovinylene group serves as an acceptor unit and a thienyl group acts as a donor unit in a D-A-D configuration. These molecules achieved excellent solubility due to their long-branched alkyl chains. The current work encompasses their structural, photophysical, thermal, electrochemical, theoretical, and photoelectrochemical studies, establishing structure-property relationships. PC1-2exhibit λabsand λemiin the range of 389-404 and 448-515 nm, respectively, with a band gap in the range of 2.88-2.92 eV. Electrochemical studies confirm the feasibility of electron injection, regeneration, and recombination. The introduction of an additional electron-withdrawing group (cyanovinylene group) on the dye PC1skeleton endows it with a higher dye loading capacity, high hole injection, and a strengthened intramolecular charge transfer (ICT) effect, resulting in a redshifted ICT absorption with a higher molar extinction coefficient. Among the two new dyes, the device based on PC1achieved the highest power conversion efficiency (PCE) of 0.027% with a short-circuit current density (JSC) of 1.29 mA·cm-2, open-circuit voltage (VOC) of 67 mV, and fill factor (FF) of 31%, whereas the device with dye PC2performed less efficiently (PCE: 0.018%, JSC: 0.92 mA·cm-2, VOC: 68 mV, and FF: 30%). Conclusively, the study provides insights into the intricacies involved in the structural modification of carbazole-based p-type dyads for the development of highly efficient DSSCs. © 2022 American Chemical Society. All rights reserved.Item CCD Sensor Based Cameras for Sustainable Streaming IoT Applications With Compressed Sensing(Institute of Electrical and Electronics Engineers Inc., 2023) Gambheer, R.; Bhat, M.S.This paper presents a comprehensive study of compressed sensing (CS) techniques applied to Charge Coupled Device (CCD) and Complementary Metal-Oxide Semiconductor (CMOS) sensor-based cameras. CS is a powerful technique for reducing the number of measurements required to capture high-quality images while maintaining a high signal-to-noise ratio (SNR). In this study, we propose a novel CS method for CCD and CMOS sensor-based cameras that combines a new sampling scheme with a sparsity-inducing transform and a reconstruction algorithm to achieve high-quality images with fewer measurements. This paper focuses on an efficient CCD image capturing system suitable for embedded IoT applications. Hardware implementation has been done for proof of concept with an onboard Field Programmable Gate Array (FPGA) performing the compression. This hardware module is used over a wireless network to transmit and receive images under different test conditions with both CMOS and CCD sensors. For each use case, Peak Signal to Noise Ratio (PSNR), average power, and memory usage are computed under different ambient lighting conditions from dark to very bright. The results show that, a 640× 480 CCD sensor with compressed sensing with a sparsity of 0.5, provides 13% power saving and 15% memory saving compared to uncompressed sensing in no-light condition, resulting in 25.76 dB PSNR. Whereas, in no light condition, CMOS sensor does not capture any image at all. These results shows that the CCD image capturing system with compressed sensing can be conveniently used for embedded IoT applications. The data recovery from wireless sensor network is done at a central office where computing time and processing power resources are not constrained. The weight of the CCD camera is approximately 100 grams with modular build approach. © 2013 IEEE.Item Performance analysis of hybrid perovskite solar cells based on different halide ions(Elsevier Ltd, 2025) Jarwal, D.K.; Mishra, A.K.; Dubey, C.; Jangid, A.K.; Bhargava, K.; Kumar, R.; Rawat, G.Here, we have investigated the importance of incorporating different halide ions into perovskite material of the hybrid perovskites-based solar cells (PSCs) and optimized the performance of the PSCs. The n-i-p device structure as FTO/ZnOS/Absorber Material/CuO/Au, is used, where ZnOS and CuO are as electron and hole transport layers, respectively. The CH3NH3PbI3, CH3NH3PbBr3 and CH3NH3PbI3?xClx are exploited as an active absorber layer, with FTO and Au serving as front and back electrodes, respectively. Their performance is studied in terms of various performance parameters viz. Open-circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF), and power conversion efficiency (PCE). Moreover, a systematic optimization and comparison is conducted to examine the influence of perovskite layer thickness, defect density, and operating temperature on the performance of the three modelled PSCs. The results show that CH3NH3PbI3 based hybrid PSC exhibits the highest PCE of 25.34 % at 300 K, at a defect density of 1015cm?3 and absorber layer thickness of 600 nm. The other key parameters include VOC of 1.15 V, JSC of 25.21 mA/cm2 and FF of 86.4 %. The analysis highlights the importance of numerical simulations in predicting the influence of structural variations in perovskite materials on performance of the hybrid perovskite solar cells. © 2025 Elsevier Ltd