Highly Efficient Vacuum-Processed Organic Solar Cells Containing Thieno[3,2‑<i>b</i>]thiophene-thiazole

Abstract

Two novel electron-donor molecules based on donor−π-conjugated linker–acceptor structure with compact packing and intramolecular charge-transfer characteristics were synthesized for the preparation of efficient organic solar cells. The donor molecules featuring an electron-rich triphenyl amine as the electron-donor unit, dicyanovinylene as the acceptor unit, and π-conjugated linkers of thienothiophene, thiophene, and thiazole units were synthesized. The π-conjugated linkers were carefully designed to have a planar structure, an efficient conjugation length, and appropriate energy levels for a compact packing in the solid state. The vacuum-processed solar cells fabricated using the donor molecules of DTTh and DTTz exhibited average power-conversion efficiencies (PCEs) of 5.4 and 6.2% (the highest PCE obtained was 6.37%) under AM 1.5G illumination with an intensity of 100 mW cm^–2