The Effect of Heteroleptic Dual Acceptors on Dye-Sensitized Solar Cells.

A novel carbazole-based organic dye with heteroleptic dual electron acceptors (cyanoacrylic acid and thieno[3,4-b]pyrazine acid) on each side of a quinoxaline was designed, and its electronic and optical properties were investigated theoretically for dye-sensitized solar cells (DSSCs). To gain insight into the factors responsible for photovoltaic efficiency, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations of these dyes were performed. The absorption spectrum of the dyes showed different forms because of the different energy levels of the molecular orbital (MO) of each dye and the intramolecular energy transfer (EnT). Considering the overall properties, the asymmetric organic dye containing the heteroleptic dual acceptors showed a competitive conversion efficiency, greater red-shift, broader absorption spectra, and higher molar extinction coefficient compared to a single acceptor in the conversion efficiency of the DSSCs. These results indicate that heteroleptic dual acceptors produces good photovoltaic properties for DSSC.