Authors: Avinash L Puyad Gunturu Krishna Chaitanya Chetti Prabhakar Kotamarthi Bhanuprakash
Publish Date: 2012/08/10
Volume: 19, Issue: 1, Pages: 275-287
Abstract
Semisquaraines SMSQ are known as donoracceptor DA type molecules whereas squaraines SQ which differs from SMSQ by an extra donor group are more or less biradicaloids in nature The effect of the additional donor group in SQ which changes the nature of the molecule on geometrical and electronic structure are studied here and compared with the corresponding SMSQ It is noticed from the geometrical parameters that a strong resonance exists in SQ whereas disparity in carboncarbon bond lengths of central C4 ring is seen in SMSQ dyes The increasing and decreasing of antibonding interactions between central C4 ring and side donor groups cause destabilization of HOMO and stabilization of LUMO respectively in case of SQ compared to SMSQ molecules This leads to decreasing the HOMOLUMO gap and promotes biradicaloid character of SQ The absorption maxima obtained by using TDDFT method with BLYP B3LYP BHandHLYP CAMB3LYP and M062X functionals are not in good agreement with experimental results On the other hand SACCI method gives better results for all the molecules From this work we can evolve a design principle of these molecules which play a role as sensitizers in dye sensitized solar cells
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