Electronic and photovoltaic properties of triphenylamine-based molecules with D-π-A-A structures

Four organic dyes (AP25, AP26, AP27, and AP28) with triphenylamine (T) as a donor coupled with different bridge groups of cyclopentadithiophene (CPDT) and quinacridone (QA), the auxiliary acceptor groups thienothiophene (TT) and benzothiadiazole (BTZ), are theoretically investigated in this paper for dye-sensitized solar cells (DSSC). DFT is used to calculate the ground-state properties of dyes, and TDDFT provides an understanding of the excited-state properties of dyes. The parameters affecting photoelectric conversion efficiency (PCE) of DSSC, correlating with Voc and Jsc were calculated to compare the photovoltaic performance of investigated dyes. Among those dyes, the results show that AP27 molecule has better photoelectric properties due to redshift absorption spectrum, larger LHE, longer fluorescent lifetime (z1) and excited-state lifetime (z2), and the higher mu normal. These results suggest that the CPDT-bridge linked with BTZ auxiliary acceptor is a promising design to develop PCE on DSSC.