A Promising Candidate with D‐A‐A‐A Architecture as an Efficient Sensitizer for Dye‐Sensitized Solar Cells

A series of metal‐free organic dyes with electron‐rich (D) and electron‐deficient units (A) as π linkers have been studied theoretically by means of density functional theory (DFT) and time‐dependent DFT calculations to explore the effects of π spacers on the optical and electronic properties of triphenylamine dyes. The results show that Dye 1 with a structure of D‐A‐A‐A is superior to the typical C218 dye in various key aspects, including the maximum absorption ( λ max =511 nm), the charge‐transfer characteristics ( D /Δ q / t is 5.49 Å/0.818 e − /4.41 Å), the driving force for charge‐carrier injection (Δ G inject =1.35 eV)/dye regeneration (Δ G regen =0.27 eV), and the lifetime of the first excited state ( τ =3.1 ns). It is thus proposed to be a promising candidate in dye‐sensitized solar cell applications.