Family of Chiral Ferroelectric Compounds with Widely Tunable Band Gaps

Das, R and Swain, D and Mahata, A and Prajapat, D and Upadhyay, SK and Saikia, S and Reddy, VR and De Angelis, F and Sarma, DD (2023) Family of Chiral Ferroelectric Compounds with Widely Tunable Band Gaps. In: Chemistry of Materials .

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Abstract

Intense research activities have been exploring the possibility of harnessing solar energy via photovoltaic and photocatalytic applications of ferroelectric materials using the built-in electric field for an efficient separation of photoexcited charge carriers. However, one of the most important bottlenecks in these efforts is to find ferroelectricity in suitably low-band-gap materials for harvesting a sizable part of the solar spectrum, with most of the known ferroelectric materials having band gaps larger than 2.5 eV. In the present work, we show that the known chiral and polar compound, (R-/S-MBA)2CuCl4, with MBA = α-methyl benzylamine, is also ferroelectric and its ligand-to-metal charge transfer (LMCT) band gap (�2.53 eV) can be systematically decreased via substitution of Cl- with Br- forming the solid solution (R-/S-MBA)2CuCl4-xBrx. These compounds retain their chiral ferroelectric state until x = 2 and reach a significantly low band gap of �2.09 eV for (R-/S-MBA)2CuCl2Br2, which is the smallest band gap reported so far among layered hybrid ferroelectric materials. We elucidate the origin of the band gap reduction and other changes in the electronic structure with the help of state-of-the-art electronic structure calculations. Chiral ferroelectrics constitute an interesting class of materials, with ferroelectricity being able to discriminate between electron and hole charge transports, while chirality may have the ability to discriminate between up- and down-spin transports. © 2024 American Chemical Society.

Item Type:	Journal Article
Publication:	Chemistry of Materials
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to author
Keywords:	Charge transfer; Electric fields; Electronic structure; Energy gap; Ferroelectricity; Hybrid materials; Solar energy; Solar power generation, Bandgap materials; Built-in electric fields; Ferroelectric compounds; Ferroelectrics materials; Low band gap; Photocatalytic application; Photovoltaic applications; Research activities; Tunable Band-gap; Widely tunable, Ferroelectric materials
Department/Centre:	Others
Date Deposited:	01 Mar 2024 10:38
Last Modified:	01 Mar 2024 10:38
URI:	https://eprints.iisc.ac.in/id/eprint/84057

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