A theoretical approach of star-shaped molecules with triphenylamine core as sensitizer for their potential application in dye sensitized solar cells

This work is supplying an in-depth investigation of the optical, electronic, and charge transfer properties for heteroatom effects on the starburst triphenylamine derivative, molecule WD8-c-1, which has been studied in our previous work. The geometry and relevant electronic properties of WD8-c-1 and its derivatives in ground state for photovoltaic applications were simulated by the B3LYP/6-31G (d,p) method. Their absorption spectra have been calculated at the TD-PBE0/6-31 + G (d,p) level. The results indicate that the oxygen and sulfur atom substituents affect the distributions of frontier molecular orbitals and energy gap of WD8-c-1 significantly. Moreover, the electron could transfer from excited sensitizer into the conduction band (CB) of TiO₂. The heteroatom substituent affect the absorption spectra of WD8-c-1 significantly. The hole transfer rates of WD8-c-1 and its derivatives are higher than that of N,N'-diphenyl-N,N'-bis(3-methlphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) and WD8-c-1-S owns the smallest hole reorganization energy (λ_h) value among the investigated molecules. The introducing of heteroatom affect the short-circuit current density and open-circuit photovoltage properties of WD8-c-1 and its derivatives significantly.