A novel dibenzosuberenone bridged D-A-π-A type dye: Photophysical and photovoltaic investigations

Abstract

In this study, a novel dibenzosuberenone based organic dye comprising triphenylamine (TPA) as the electron-rich unit and a dibenzosuberenone as the central core and an additional acceptor and, benzene as the π linker unit, and an aldehyde as the electron-deficient unit to form π-conjugated donor-acceptor-π-bridge-acceptor (D-A-π-A) system was designed. The dye was successfully synthesized by Suzuki coupling reaction using a novel one pot approach, i.e. two different aryl boronic acids containing electron withdrawing group (EWG) and electron donating group (EDG) at para positions were added to the reaction medium at the same time. As expected, three different coupling products were obtained in one-pot/one step. Structures of synthesized compounds were fully characterized by NMR, IR, HRMS UV-Vis, and fluorescence spectroscopy techniques. The photophysical and photovoltaic properties of the dye were elucidated and, DFT theoretical calculations were performed to support the investigations. The dye showed red shift of absorption and emission maxima, 388 and 571 nm, respectively. Moreover, a medium fluorescence quantum yield (0.27) and a very large Stokes shift (183 nm) of the dye was also found. The calculated HOMO and LUMO energies of the ground state optimized geometry of the dye were -5.360 and -2.521 eV, respectively, and the bandgap was 2.838 eV. The power conversion efficiency (%) value for the dye were also calculated as 3.01%. The findings provide a beneficial reference to the development of organic dyes containing dibenzosuberenone groups in more efficient dyes for DSSCs.