Novel fluoranthene dyes for efficient dye-sensitized solar cells

Three, novel, fluoranthene-based dyes, 2-cyano-3-(5-(7,12-diphenylbenzo[k]fluoranthen-3-yl)thiophen-2-yl)acrylic acid, 2-(5-((5-(7,12-diphenylben-zo[k]fluoranthen-3-yl)thiophen-2-yl)methylene)-4-oxo-2-thioxothiazolidin-3-yl)acetic acid and 2-cyano-3-(4-(2-(7,12-diphenylbenzo[k]fluoranthen-3-yl)ethynyl) phenyl) acrylic acid, were synthesized for application as sensitizers in dye-sensitized solar cells. In each dye, the 7,12-diphenyl-benzo[k]fluoranthene moiety acted as electron donor with phenyl and thiophene units as electron spacers and carboxylic acid as electron acceptor. Tuning of the HOMO and LUMO energy levels was conveniently accomplished by changing the spacer and acceptor moiety, as confirmed using electrochemical measurements. Maximum solar energy:electricity conversion efficiency was 4.4% under AM 1.5 solar simulator (100 mW cm−2) for 2-cyano-3-(5-(7,12-diphenylbenzo[k]fluoranthen-3-yl)thiophen-2-yl)acrylic acid. The results suggest that dyes based on fluoranthene donor are promising candidates for high performance, dye-sensitized solar cells.