Enhancing the photoresponse by CdSe-Dye-TiO2 -based multijunction systems for efficient dye-sensitized solar cells: A theoretical outlook.

This work presents theoretical modeling of some systems, using density functional theory (DFT), for enhancing the photoresponse of a dye-sensitized solar cell. The optimization of the dye (NKX 2587) as well as the dye derivatives was carried out using B3LYP and 6-311g (d,p) level of theory, using DFT as incorporated in Gaussian 03 level of programming. The HOMO-LUMO energy gaps are lower for (CdSe)13 -Dye-(TiO2 )6 multijunction systems in comparison with both the isolated dyes as well as dye-TiO2 systems. The absorption peaks were found to be mostly red-shifted for (CdSe)13 -Dye-(TiO2 )6 multijunction systems with respect to the Dye-TiO2 systems, indicating the enhancement of the absorption behavior of the dye sensitizer by its interaction with the CdSe framework. The results thus indicate some sort of co-sensitization of the TiO2 by the dye sensitizer as well as the CdSe quantum dot and are hence expected to increase the efficiency of the solar device.