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Sponsored Research Projects (click)
“Bandgap Engineered Lead-free Halide Double Perovskites with Enhanced Emission Properties” under the Board of Research in Nuclear sciences (DAE-BRNS), 58/14/06/2023-BRNS/37030. [Duration: 2023-2026, Amount: Rs. 29,20,350/=] [Principal Investigator]
“Charge transfer dynamics in non-fullerene small molecule organic solar cell” under the Department of Science and Technology (DST), Core Research Grant no. CRG/2019/003197. [Duration: 2021-2024, Amount: Rs. 61,20,587/=] [Principal Investigator]
“Fully Standalone type Photovoltaic fed Zero carbon battery charging station for institute’s EVs(without grid connectivity)” :IITH/DES/F257/2022-23/G470 [Duration 2022-2023, Amount: Rs 29,52,000] [Co-PI]
“Interface-engineered and energy-efficient organic solar cells based on porphyrin small molecules” under BRICS-STI 2017 grant in partnership of China and Brazil [Duration: 2019-2022, Amount: Rs 31,48,500/=] [Principal Investigator]
“Hot and Multi Electron Mediated Photoelectrochemical Methods of High Efficiency Water Splitting,” under SPARC, MHRD, SPARC/2018-2019/P301/SL [Duration 2019-2021, Amount: Rs 53,43,295/=] [Co-PI]
“Oxygen and Light-mediated effects on the stability of two dimensional perovskite Solar Cells” under IUSSTF BASE fellowship scheme [Duration May-July, 2019, Amount: Rs 9, 42, 800/=] [Principal Investigator]
"Development of femtosecond transient absorption spectrometer for exciton dissociation studies at a donor/acceptor interface in hybrid solar cell" under the Department of Science and Technology (DST), Young Scientist Scheme no. DST/YSS/2015/000008. [Duration: 2016-2019, Amount: Rs. 21,20,000/=] [Principal Investigator]
“Photoluminescence studies on rare-earth modified lead-free ferroelectric ceramics” under CSIR extramural research grant [Duration: 2016-2019, Amount: Rs. 20,60,000/=] [Principal Investigator]
“Development of economically viable efficient Hybrid organic solar cells” IIT Hyderabad grant number SG/IITH/F140/2016-17/SG-25. [Duration: 2016-2018, Rs. 3,00,000/=] [Principal Investigator]
“Investigations of the electric field driven effects on structural, ferroelectric and photoluminescence properties in Rare earth substituted lead free piezoceramics,” under UGC-DAE CSR grant [Duration: 2017-2020, Amount: 13,51,800/=] [Co-PI]
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Ultrafast Time-resolved spectroscopy and Ultrafast Nonlinear Optics
Femtosecond transient absorption and photoluminescence spectroscopy for charge photo-generation and charge transport investigations in organic molecule based photovoltaic devices.
It is a powerful scientific technique used to study the excited state dynamics of different systems on extremely short timescales.
Recent Publications:
“Ultrafast intramolecular charge transfer dynamics and nonlinear optical properties of phenothiazine-based push–pull zinc porphyrin,” C. Biswas, P.S.Gangadhar, L. Giribabu, P. Chetti, D. Banerjee, V. Rao Soma, Sai Santosh Kumar Raavi, Journal of Photochemistry & Photobiology, A: Chemistry, vol 433 114141 (2022)
“Metalated porphyrin-napthalimide based donor-acceptor systems with long-lived triplet states and effective three-photon absorption,” Md Soif Ahmed, C. Biswas, B. Bhavani, S. Prasanthkumar, D. Banerjee, V. Kumar, P. Chetti, L. Giribabu, V. R. Soma, Sai Santosh Kumar Raavi, Journal of Photochemistry & Photobiology, A: Chemistry, vol 435 114324 (2023)
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Solar Cell devices
Dye Sensitized Solar cells, QD-Sensitized Solar Cells, Bulk-Heterojunction Solar Cells, Perovksite Solar Cells
All energy is ultimately derived from the sun, and harvesting it directly through solar power seems to be the best way to transition to renewable energy.
Recent Publications:
“Deciphering the role of (Er3+/Nd3+) co-doping effect on TiO2 as an improved electron transport layer in perovskite solar cells,” V.S. Katta, R. Dileep, E. Ramasamy, G. Veerappan, and Sai Santosh Kumar Raavi, Solar Energy, vol. 262, 111801 (2023).
"Understanding Improved Performance of Vacuum-Deposited All Small-Molecule Organic Solar Cells Upon Postprocessing Thermal Treatment,” S Madduri, V G Kodange, Sai Santosh Kumar Raavi, SG Singh, in IEEE Journal of Photovoltaics, vol. 13, pp. 411-418 (2023)
“Plasmonic Au-NPs embedded Ytterbium-doped TiO2 nanocomposites photoanodes for efficient indoor photovoltaic devices,” V. S. Katta, V. R. Chappidi, Sai Santosh Kumar Raavi, Appl. Surf. Sci. vol 611, 155728 (2023)
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TA Spectroscopy and Device Physics.
Hot Carrier Relaxation Slowdown: Femtosecond transient absorption spectroscopy (fs-TAS) reveals that WS2/CsPbBr3 hybrid nanocomposites exhibit slower hot carrier (HC) relaxation (from ~6 ps in CsPbBr3 NCs to ~10 ps in nanocomposites at 17.7 µJ cm⁻² excitation fluence) due to a hot-phonon bottleneck, with HC temperature increasing from 856 K in pristine NCs to 1181 K in nanocomposites.
Enhanced Charge Transfer and Photodetector Performance: Electron transfer from CsPbBr3 NCs to WS2 nanosheets in nanocomposites is faster (20.9–66.9 ps vs. 38.0–102.4 ps in pristine NCs at 17.7–99.8 µJ cm⁻²), leading to significant photodetector improvements, with ~400% increase in photocurrent, ~420% in responsivity, and ~200% in detectivity compared to pristine devices.
Recent Publications:
“Tunable Near-infrared Emission and Three-Photon Absorption in Lanthanide-doped Double Perovskite Nanocrystals,” Md. Soif Ahmed, L. Sireesha, S K. Nayak, R. Bakthavatsalam, D. Banerjee, J. Kundu, V. Rao Soma, Sai Santosh Kumar Raavi , Nanoscale, vol 15, 9372-9389 (2023)
“Enhanced femtosecond nonlinear optical response in Mn-doped Cs2AgInCl6 nanocrystals” Md. Soif Ahmed, SK. Nayak, L. Sireesha, J. Rathod, V. Rao Soma, Sai Santosh Kumar Raavi , Optics Lettes, vol 48, 35193522 (2023).
“Femtosecond nonlinear optical properties of polycyclic aromatic hydrocarbon-based Benzo [e] pyrene derivatives,” S. K. Nayak, R. Kore, Md Soif Ahmed, P. Verma, R. Vallavoju, D. Banerjee, S. Pola, V. R. Soma, P. Chetti, Sai Santosh Kumar Raavi, Opt. Materials, vol. 137, pp 113603 (2023)
The effects of Au NPs into the Yb-doped TiO2 photoanodes in the Indoor photovoltaics:
The rutile phase is reduced and the fermi levels are shifted when Gold nanoparticles (Au NPs) are added to Yb-doped TiO2 as a photoanode in indoor photovoltaic (IPV). The plasmonic impact of gold nanoparticles (Au NPs) improves light absorption, lowers charge transport resistances, and also boosts conductivity, which improves the power conversion efficiency of the IPV.
Ultrafast intramolecular charge transfer dynamics of Porphyrin:
Comprehensive investigations of the ultrafast photophysical properties and charge injection dynamics (adsorbed on mesoporous TiO2) of phenothiazine-functionalized push–pull Zinc porphyrin (LG6) utilizing a benzothiadiazole (BTD) as an acceptor unit is demonstrated based on femtosecond transient absorption (fs-TA) spectroscopy measurements.
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