Molecular engineering on D-π-A organic dyes with flavone-based different acceptors for highly efficient...

The improvement of new organic flavone-based donor-spacer-acceptor (D-π-A) type dye molecules of the 3-(4-hydroxypiperidin-2-yloxy)-7-hydroxy-2-(3,4-dihydroxyphenyl)-4H-chromen-4-one (D1), 7-hydroxy-2-(3,4-dihydroxyphenyl)-3-(piperidin-4-yloxy)-4H-chromen-4-one (D2), and 3-((2-aminopyridin-4-yloxy)methoxy)-7-hydroxy-2-(3,4-dihydroxyphenyl)-4H-chromen-4-one (D3) were successfully designed and synthesized for dye-sensitized solar cells (DSSCs).

Here, we discuss the synthesis of flavone compounds as well as their photophysical and electrochemical characterization. Using the Gaussian 09w software, the electronic structures and apsorption spectra have been calculated at the B3LYP, B3PW91, CAM-B3LYP, MPW1PW91, PBEPBE, and ωB97XD theory with the 6-311G(d,p) basis sets.

The computed values of the D2 molecule ground state optimized HOMOs-LUMOs energy is well positioned for advantageous charge transfer (CT) into the semiconducting material (TiO₂) as well as the electron injection process. With a high power conversion efficiency (PCE) of 3.46% (V_OC = 0.718 V, J_SC = 7.07 mA cm^-2, and FF = 0.68), the D2 compound also demonstrated good photovoltaic (PV) properties.

These findings unequivocally demonstrate that altering the D-π-A metal-free organic material electron-withdrawing capacity is a useful strategy for enhancing the optical and electrical characteristics of the organic PV system.