Tuning the lifetime from molecular engineering of carbazole donor based metal-free organic dyes for dye sensitized solar cells – A computational approach

The metal free organic sensitizers for dye sensitized solar cells (DSSC) have been developed from carbazole donor based on D-π-A architecture. From the structural modifications, the optical and electronic properties of the dyes were tuned. In the present investigation series of carbazole donor based metal free dyes were studied using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The optimized geometry, frontier molecular orbitals, energy levels and electronic absorption spectra were studied. The natural bond orbital analysis (NBO) gives the net electron transfer from the donor to acceptor. The electrochemical properties and light harvesting efficiency of the designed dye sensitizers were calculated. The π spacer increase induced the absorption peak and red shift was noted. The life time was increased by adding phenyl ring in the donor side. Based on theoretical calculations designed dye molecules are evaluated for DSSC application.