Theoretical Study of New Heteroleptic Ruthenium Complex with Conjugated Phenoxazines

Abstract

In this study, novel ruthenium complexes substituted with donor antenna group were designed and studied theoretically to enhance the photovoltaic. We have compared the well known N3 dye and Ru(II) complexes substituted with antenna groups, such as a conjugated phenoxazine (POZ) of one site, two conjugated POZs of both site to bipyridine. Molecular orbital analysis confirmed that the HOMOs of N3 are localized over the NCS ligand orbitals of N3, however, the HOMO, HOMO-1 and HOMO-2 of Ru(dcbpy)(pbpy)(NCS)2 and Ru(dcbpy)(dpbpy)(NCS)2 are localized over the NCS or POZ antenna ligand. The TDDFT calculations showed that the complexes with POZ donor antenna had panchromatic absorption spectra in the region above 400 nm compared to N3 dye. Absorption bands between 400 and 500 nm were ascribed to transitions of antenna unit. From these results, it is shown that substituted antenna moiety enhanced their electronic and optical properties as dye sensitizer, and it is expected that these ruthenium complexes with POZ antenna would show better performance than N3 dye in conversion efficiency for DSSCs.