Molecular engineering of triphenylamine -based metal-free organic dyes
for dye-sensitized solar cells
Abstract
In this study, the photovoltaic properties of the organic dyes based on
triphenylamine having a D--A structure including TC201, TC202, TC203,
TC601, H-P, F-P, FF-P, T-F, and P1B were investigated theoretically. In
this model, triphenylamine was used as an electron donor, cyanoacrylic
acid, and benzoic acid as the electron acceptors, and anthracene phenyl,
anthracene vinyl phenyl, anthracene ethynyl phenyl, ethynyl anthracene
phenyl, styryl phenyl, styryl-2-fluorophenyl, styryl-2,6-difluorophenyl,
styryl furan, and styryl as the π-conjugated systems. The results show
that a change in the -conjugated system and electron acceptor affect
the properties of the dye-sensitized solar cell (DSSC). Also, TC601 dye
having the ethynyl anthracene phenyl -conjugated system shows the
highest charge transfer distance (DCT) and the least overlap of the
electron-hole distribution (S) in comparison with other dyes. Moreover,
the presence of a triple bond in the vicinity of triphenylamine
increases the resonance effect of the -electrons that facilitates the
process of charge transfer in this dye. Spectroscopic analysis shows
that H-P and F-P dyes have the higher molecular absorption coefficients
and TC202, TC203, F-P, and T-F dyes show a red shift in comparison with
other dyes. Moreover, the voltage-current curve of the studied dyes
shows that the highest values of the open circuit voltage and short
circuit current density are related to P1B and TC601 dyes, respectively.
Finally, TC601 and P1B are proposed as the best candidates to be used in
the DSSCs due to their maximum incident photon to current conversion
efficiency.