Spectral and optoelectronic studies on 7,12,17-trioxa and 7,12,17-trithia [11] helicenes: a DFT view

Abstract

Density functional theory has been used to analyse the structural, spectral, charge transport and nonlinear properties of 7,12,17-trioxa [11] helicene and 7,12,17-trithia [11] helicene. The optimised geometries of TOH and TTH shows that carbon–carbon bond lengths of inner fused rings vary from terminal rings, as a consequence of generated torsional strain. The IR-spectra displays characteristics peaks in the region of 750–1550 cm⁻¹ in TOH and a slight shift occurs to lower frequency in case of TTH. The vibrational circular dichroism peaks have major contributions from in and out of plane bending and minor contribution from C=C stretching of fused aromatic rings. From ionisation and reorganization energy values it is evident that TOH and TTH can act as hole transport material for OLED device. As a consequence of extended conjugation in studied system, the higher values of polarizability and hyperpolarizability reflects their role in NLO devices.

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