Somobrata Acharya
Indian Association for the Cultivation of Science (IACS), Kolkata
Somobrata Acharya received his Ph.D. degree from IACS in 2003. He carried out post-doctoral research at Ben Gurion University in Israel. He is a Fellow of the International Centre for Young Scientists (ICYS) and the World Premier International (WPI) Research Centre for Materials Nanoarchitectonics (MANA) at the National Institute of Materials Science (NIMS) in Japan. He is currently Senior Professor at the School of Applied and Interdisciplinary Sciences at IACS. He is a Fellow of the National Academy of Sciences. He is a recipient of the SERB-STAR Award 2020 of the Science and Engineering Research Board, the CRSI Bronze Medal 2020 of the Chemical Research Society of India, and the MRSI Medal 2020 of the Materials Research Society of India. He was elected Fellow of IASc in 2023.
Session 3A: Lectures by Fellows/Associates
Chairperson: U C Mohanty, Centre for Climate Smart Agriculture, Bhubaneswar
Unveiling Solid State Luminescence from Noncovalent Two-Dimensional Molecular Crystals Fabricated at Air–Water Interface
Two-dimensional (2D) molecular crystals represent an important class of materials for advanced optoelectronic applications. Owing to the monolayer or few-layered thickness, unique properties can be realized from the 2D molecular crystals which are different from their bulk organic counterparts. We introduce a promising pressure-triggered strategy to fabricate noncovalent free-standing 2D molecular crystals [1, 2]. The molecular thick, micron-long, yet stable 2D molecular crystals are formed in a controllable and efficient way on the flat-water surface having small roughness. The formation of 2D molecular crystals at different stages is monitored using in situ synchrotron grazing incidence X-ray diffraction measurements and atomic force microscopy. The crystal structures are probed using in situ synchrotron grazing incidence X-ray diffraction measurements and selected area electron diffraction patterns using transmission electron microscopy. The resultant 2D molecular crystals show a marked enhancement of luminescence in the solid state. The critical conformation of molecules within the 2D crystals concomitantly leads to the reduced singlet-triplet energy gap and strong spin-orbit coupling for effective mixing of the singlet and triplet states, which explains the room temperature phosphorescence origin of the luminescence and luminescence enhancement.