A COMBINED THEORETICAL AND EXPERIMENTAL APPROACHES TOWARDS DESIGNING NIR DYES FOR DYE-SENSITISED SOLAR CELLS

Sensitizing dyes especially having capability of sharp light absorption in the near infrared region play a pivotal role towards enhancing the photovoltaic efficiency of dye-sensitised solar cells. Effort has been directed towards the optimization of suitable calculation parameters for the theoretical calculations to assist the design of novel sensitizers for the dye-sensitised solar cells using Gaussian program package. Suitability of the calculation parameters as well as calculated results using the same model, unsymmetrical squaraine dye (SQ-1) was designed, synthesized and used for their characterisation and photovoltaic applications. Calculation results were performed in both ground and excited states of this molecule and indicate that B3LYP and B3PW91 are quite suitable hybrid functional for theoretical calculation using DFT and 6-311G basis set. Electronic absorption maximum for SQ-A in ethanol solution exhibits the peak at 650 nm which was found to be only 47 nm (0.04 eV) higher as compared to the calculated value (603 nm) using PCM solvent model under TD-DFT.