Naphthalimide-phenothiazine based A’-π-D-π-A featured organic dyes for dye sensitized solar cell applications

The effect of naphthalimide as auxiliary acceptor in the PTz-based dyes for dye-sensitised solar cell (DSSC) application is reported. In this regard, two new organic dyes with N-alkylated phenothiazine (PTz) core were synthesized by substitution of naphthalimide at C-3 of the PTz via triple bond and incorporation of an electron acceptor at C-7 position. Photophysical and electrochemical studies were carried out to assess the performance of the dyes on spectral coverage and to determine the redox energy levels, respectively. Charge distribution and electron transfer process of the optimized dyes were rationalised via theoretical studies. DSSCs fabricated with these dyes showed an optimal efficiency of 4.9 % for a device fabricated with iodide/triiodide electrolyte.