Department of Chemistry

Cesium lead halide perovskite nanocrystals (PNCs) belong to the flourishing research area in the field of photovoltaic and optoelectronic applications because of their excellent optical and electronic properties. Mainly, Cesium lead bromide (CsPbBr3) NCs with bright green photoluminescence (PL) and narrow full-width at half-maximum (FWHM) of <25 nm are the most desirable for television displays and green-emitting LEDs. However, challenges with respect to CsPbBr3 PNCs‘ stability, limit their usage in practical applications. The recent findings of Dr Nimai Mishra and his research team assert that surface passivation with an additional ligand could be an excellent, easy, and facile approach to enhancing the photoluminescence and stability of PNCs.

Dr Nimai Mishra, Assistant Professor, Department of Chemistry, along with his research group comprising of students pursuing PhD under him, Dr V G Vasavi Dutt, Mr Syed Akhil, Mr Rahul Singh, and Mr Manoj Palabathuni have published their research article titled “Year-Long Stability and Near-Unity Photoluminescence Quantum Yield of CsPbBr3 Perovskite Nanocrystals by Benzoic Acid Post-treatment“ in The Journal of Physical Chemistry C (A Q1 journal published by ‘The American Chemical Society’) having an impact factor of ~4.2.

In this article, the research group addresses the stability issues of green-emitting CsPbBr3 PNCs with simple post-treatment using benzoic acid (BA). A remarkable improvement in PLQY from 69.8% to 97% (near unity) was observed in benzoic acid-treated CsPbBr3 PNCs. The effective surface passivation by benzoic acid is also apparent from PL decay profiles of BA-CsPbBr3 PNCs. The long-term ambient stability and stability against ethanol of BA-CsPbBr3 PNCs are also well presented in the research. The PL intensity of untreated CsPbBr3 PNCs is completely lost within five months since the synthesis date, while ̴ 65% of initial PL intensity is preserved for BA-CsPbBr3 PNCs even after one year.

Furthermore, BA-CsPbBr3 PNCs exhibits excellent photo-stability where 36% of PL is retained while PL is completely quenched when the PNCs are exposed to 24 hours of continuous UV irradiation. Importantly, BA-CsPbBr3 PNCs show excellent stability against ethanol treatment as well. Finally, green, emitting diodes using BA-CsPbBr3 PNCs are fabricated by drop-casting NCs onto blue-emitting LED lights. Thus a simple benzoic acid posttreatment further presents the scope of use of these materials display technologies.

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‘Energy Conversion & Management’ is a journal that belongs to the top 2% of the “Renewable Energy, Sustainability, and the Environment” subject category. Publishing a paper with an impact factor of 9.7 in such a journal is a considerable achievement. Assistant Professors Dr Sabyasachi Chakrabortty and Dr Mahesh Kumar Ravva and their PhD scholar Ms Mounika Sai Ambati from the Department of Chemistry have accomplished this by publishing a paper titled Photovoltaic/Photo-Electrocatalysis Integration for Green Hydrogen: A review in this Q1 journal.

Abstract of the research

Solar light-driven hydrogen generation via water splitting is essential to combat global warming and CO2 emission. The production of hydrogen from fossil fuels produces massive amounts of CO2. Developing a sustainable and eco-friendly approach to hydrogen production is the need of the hour. Photoelectrochemical water splitting is a clean way to produce hydrogen by using water. The hydrogen generated through water splitting is referred to as Green Hydrogen. Photoelectrochemical water splitting uses metal oxides as photocathode/anode. The challenges that occur here are stability, low efficiency, and large-scale development (reusable electrodes are essential). Hence, the primary goal is to demonstrate photoelectrodes using different metal oxides by in-situ doping of different metals to detect the challenges.

SRM AP is known for its resources and facilities for pioneering research with the support of global leaders and SME’s while sticking to compliance and international regulations. Obtaining research excellence in every field of study has been a mission of the university. Recently, 50 MSc students from the Department of Chemistry, KBN College, Vijayawada, visited our university to explore the analytical and research facilities available here.

The research areas handled by the Department of Chemistry of SRM AP include the disciplines of chemical sciences, ranging from organic, inorganic, and physical, to theoretical or computational chemistry. The department’s highly disciplinary and collaborative environment is indeed inspiring, and it continues to grab attention. The strong interactions of the university with other premier institutions across India and around the world refine the quality of analytical and research facilities available here. The students from KBN college eagerly interacted with the faculty members and research scholars. Dr Mahesh Kumar Ravva and Dr Rajapandiyan, Faculty members, coordinated the visit.

The university revels in its monumental achievement of bringing out the maiden doctorate degree holder, Dr Vasavi Dutt, within four years of its inception. Dr Vasavi Dutt enrolled as a PhD scholar in the Department of Chemistry, under the supervision of Dr Nimai Mishra, Assistant Professor, in 2018. She received the academic honour for her research thesis titled “Improvement of Photoluminescence and Achieving the Stabilization of Cesium Lead Halide Perovskite Nanocrystals for Light-emitting Applications”. Dr Vasavi has been an extremely diligent student and she mustered up immense courage to bring her research to closure even during the testing times of the pandemic.

In the words of Dr Nimai Mishra, “It was a great privilege for me to supervise Ms Vasavi, (correct me Dr Vasavi now) as my first PhD student. She joined my research lab in July 2018 when there was no lab at all, and we started our work at Chemistry BTech Lab”. Dr Mishra was gleaming with pride as he spoke more about his scholar, “During these three and a half years, I had relentless scientific discussions with Vasavi which enriched both of us. Her attitude towards research was remarkable, whenever I gave her a research problem, she used to come up with a detailed outline of how to go ahead with the project”. He also praised her for all her accomplishments which include the publication of 13 research papers, filing of 3 patents and winning the best poster in national & internal conferences.

Dr Vasavi also shared her happiness for having received the mentorship of Dr Mishra, “Working in Dr Nimai Mishra’s lab was a great experience. I had the opportunity to engage and initiate multiple research topics and collaborations. He has always encouraged me to explore new fields to broaden perspectives and bring together new ideas”. She also expressed her gratitude to him for being a welcoming and approachable mentor. “I’m eternally thankful to Dr Mishra for his friendship, empathy, and moreover, for his great sense of humour”. She currently resides in the US with her family. Now that she has successfully completed her PhD, soon she would start looking for a job or rather pursue a post-doctoral fellowship in America.

Dr Vasavi was out of words to thank the university for facilitating and bringing the best in technology and infrastructure for advanced research. “I can never thank my university enough for extending a hospitable environment and nutritious food for all the doctorate students”, she further mentioned. The university serves as a promised land for thousands of research aspirants like her to head towards their dream of making unfeigned contributions to academia.

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