Photoelectrochemical and Photocatalytic Studies of Chalcogenophene-Based Conjugated Systems

Karmakar, Himadri Shekhar (2022) Photoelectrochemical and Photocatalytic Studies of Chalcogenophene-Based Conjugated Systems. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Himadri Shekhar Karmakar (15RS006)) 15RS006.pdf - Submitted Version Restricted to Repository staff only Download (7MB)

Abstract

This thesis deals with the photoelectrochemical and photocatalytic applications of newly synthesized chalcogenophene-based small molecules and corresponding polymers formed via electrochemical polymerization. It consists of the synthesis and characterization of fused chalcogenophenes such as highly crystalline thiophene annulated fused heterocycles and polycyclic arene-fused selenophenes via site-selective selenocyclization. The site-selectivity for selenocyclization was studied using different types of substrates and observed to be dependent on the π-electron donation ability, measured via HOMO coefficient on the carbon next to the alkyne substituent of the polycyclic arenes with the higher number of the fused aromatic ring. The mobility of three of these polycyclic arene-fused selenophenes with high crystallinity was calculated to make a correlation between their structural properties with hole mobilities. It helps to get an initial idea about their performance in solar cells. Different bromo derivatives of 1,6,7,12-tetramethoxyperylene were synthesized to depict their difference in optoelectronic properties. The bromo groups are substituted with thiophene to improve their visible light absorbance, which helps to exhibit better photoelectrochemical performance. Further electrochemical polymerization to form polymer film with different thicknesses of 2,5,8,11-tetrathiophene capped-1,6,7,12-tetramethoxyperylene provides an idea about their different electrochemical performance. The photocatalytic activity of the polymer powder was investigated to estimate their efficiency in reducing CO₂ to CO.

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