Influence of Triple Bonds as π-Spacer Units in Metal-Free Organic Dyes for Dye-Sensitized Solar Cells

Abstract

Four metal-free organic sensitizers ( TC101 − TC104 ) with triple bonds in π-spacers and five reference dyes ( TC, TC105, TPC1, D5, and TH208 ) without triple bonds were applied in dye-sensitized solar cells to study the influence of triple bonds as π-spacer units on their photoelectrochemical properties and dye-sensitized solar cells (DSCs) performance. Results show that the introduction of triple bond could red-shift the dye’s absorption spectrum due to the enhancement of the π-spacer. However, the spectrum red-shift is much less than that of the introduction of double bond because of more electronegativity of triple bond. The incident photon-to-current conversion efficiency reveals that the electron transfer yield (Φ(ν) ET ) of DSCs becomes larger with the introduction of triple bond. Electrochemical impedance spectroscopy analysis reveals that the introduction of triple bond almost does not change the electron lifetimes in TiO 2 films but decreases the effective diffusion lengths.