Fabrication and performance of all-solid-state dye-sensitized solar cells using synthetic carboxylated and pyridylated chlorophyll derivatives

Abstract

All-solid-state dye-sensitized solar cells (DSSCs) based on a mesoporous TiO2 electrode were fabricated using synthetic chlorophyll derivatives as a photosensitizer and 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene as a hole-transport material. Methyl pyropheophorbides-a possessing a carboxy group in the C3-substituent as the anchoring moiety to the TiO2 surface were effective DSSCs. Direct conjugation of the COOH group with the terminus of the C3-vinyl group gave the highest solar energy-to-electricity conversion efficiency (η) of 2.25%. Insertion of a 1,3-phenylene group in the connection partially suppressed the efficiency by 25% (η = 1.68%), whereas insertion of an isomeric 1,4-phenylene moiety decreased to one third (0.75%). A pyridyl group was not useful as the sensitizer anchor due to its low binding affinity to the TiO2 electrode.