@article { ISI:000369591400061, title = {Large area chemical vapor deposition of monolayer transition metal dichalcogenides and their temperature dependent Raman spectroscopy studies}, journal = {Nanoscale}, volume = {8}, number = {5}, year = {2016}, month = {JAN}, pages = {3008-3018}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

We investigate the growth mechanism and temperature dependent Raman spectroscopy of chemical vapor deposited large area monolayer of MoS2, MoSe2, WS2 and WSe2 nanosheets up to 70 mu m in lateral size. Further, our temperature dependent Raman spectroscopy investigation shows that softening of Raman modes as temperature increases from 80 K to 593 K is due to the negative temperature coefficient and anharmonicity. The temperature dependent softening modes of chemical vapor deposited mono-layers of all TMDCs were explained on the basis of a double resonance phonon process which is more active in an atomically thin sample. This process can also be fundamentally pertinent in other emerging two-dimensional layered and heterostructured materials.

}, issn = {2040-3364}, doi = {10.1039/c5nr07401k}, author = {Pawbake, Amit S. and Pawar, Mahendra S. and Jadkar, Sandesh R. and Late, Dattatray J.} } @article {49463, title = {Lead-free Cs2AgBiCl6 double perovskite: experimental and theoretical insights into the self-trapping for optoelectronic applications}, journal = {ACS Physical Chemistry Au}, volume = {4}, year = {2024}, month = {JUL}, pages = {476{\textendash}489}, type = {Article}, abstract = {

Lead-free double perovskites (DPs) will emerge as viable and environmentally safe substitutes for Pb-halide perovskites, demonstrating stability and nontoxicity if their optoelectronic property is greatly improved. Doping has been experimentally validated as a powerful tool for enhancing optoelectronic properties and concurrently reducing the defect state density in DP materials. Fundamental understanding of the optical properties of DPs, particularly the self-trapped exciton (STEs) dynamics, plays a critical role in a range of optoelectronic applications. Our study investigates how Fe doping influences the structural and optical properties of Cs2AgBiCl6\ DPs by understanding their STEs dynamics, which is currently lacking in the literature. A combined experimental{\textendash}computational approach is employed to investigate the optoelectronic properties of pure and doped Cs2AgBiCl6\ (Fe{\textendash}Cs2AgBiCl6) perovskites. Successful incorporation of Fe3+\ ions is confirmed by X-ray diffraction and Raman spectroscopy. Moreover, the Fe{\textendash}Cs2AgBiCl6\ DPs exhibit strong absorption from below 400 nm up to 700 nm, indicating sub-band gap state transitions originating from surface defects. Photoluminescence (PL) analysis demonstrates a significant enhancement in the PL intensity, attributed to an increased radiative recombination rate and higher STE density. The radiative kinetics and average lifetime are investigated by the time-resolved PL (TRPL) method; in addition, temperature-dependent PL measurements provide valuable insights into activation energy and exciton{\textendash}phonon coupling strength. Our findings will not only deepen our understanding of charge carrier dynamics associated with STEs but also pave the way for the design of some promising perovskite materials for use in optoelectronics and photocatalysis.

}, doi = {https://doi.org/10.1021/acsphyschemau.4c00008}, author = {Rahane, Swati N. and Rahane, Ganesh K. and Mandal, Animesh and Jadhav, Yogesh and Godha, Akshat and Rokade, Avinash and Shah, Shruti and Hase, Yogesh and Waghmare, Ashish and Saykar, Nilesh G. and Roy, Anurag and Salgaonkar, Kranti N. and Dubal, Deepak and Makineni, Surendra K. and Dzade, Nelson Y. and Jadkar, Sandesh R. and Rondiya, Sachin R.} }