Fine-tuning of triarylamine-based photosensitizers for dye-sensitized solar cells

The synthesis of a series of novel organic photosensitizers based on modified triarylamine motives has been achieved. The new "push-pull" dyes, bearing one to three naphthyl units in place of phenyl rings, have been successfully obtained following original synthetic routes. The structural, optical and electrochemical properties of these chromophores were studied by combining crystallographic, experimental and theoretical data. We further present a systematic study of this series of dyes. When embedded in dye-sensitized solar cell devices, the new photosensitizers showed good spectral response with IPCE greater than 85% from 470 to 580 nm and overall power conversion efficiencies reaching 6.6%. One of these new sensitizers, containing one naphthyl attached to the π-conjugated linker and having phenyl rings on the outside, led to the highest molar extinction coefficient and energy conversion efficiency of the series while exhibiting higher electron lifetime.