New carbazole-based organic dyes with different acceptors for dye-sensitized solar cells: Synthesis, characterization, DSSC fabrications and density functional theory studies

Abstract Carbazole dyes applied in dye-sensitized solar cells (DSSCs) are essential class of organic molecules. Two novel organic dyes DRA-BDC and DTB-BDC including rhodanine-3-acetic acid/thiobarbituric acid as electron acceptors and N, N-butyl dicarbazole structural as electron donor/spacer have been designed as photosensitizers for DSSCs. Both prepared dyes were characterized by IR, 1H-NMR, 13C-NMR, mass spectroscopy and CHN analysis. Results of photophysical properties, the UV- Visible spectra of both dyes DRA-BDC and DTB-BDC showed the higher absorption peaks at 440 and 370 nm, respectively. Also, for electrochemical properties, both structures showed more +ve ground state oxidation potential than I−/I−3, and more –ve excited state oxidation potential than the conduction band edge of the semiconductor. However, the high performance of power-conversion was observed on the DSSCs device with DRA-BDC (η = 1.16 %) compared with DTB-BDC dye. Also, DRA-BDC recorded an open circuit voltage (VOC) = 589 mV, short circuit current density (JSC) = 2.46 mA/cm2 and fill factor (FF) = 0.79 under simulated AM 1.5G irradiation (100 mW/cm2). For the theoretical studies included polarizabilities, optimization geometry, conformational analysis, and photovoltaic analysis based on frontier orbital analysis energy evaluated by using density functional theory model (DFT) with B3LYP/6-311functional basis set.