Thieno[3,2-b]indole / 2,2′-bithiophene-based D-π-A dyes for dye sensitized solar cells

In this work, new D-π-A dyes bearing thieno[3,2-b]indole, 7-(tert-butyl)thieno[3,2-b]indole or benzo[g]thieno[3,2-b]indole as an electron-donating part, 2,2′-bithiophene unit as π-linker and 2-cyanoacrylic acid as an electron acceptor-anchoring part have been readily synthesized and used for dye-sensitized solar cells (DSSCs). In addition, thermal stability, optical and electrochemical properties of these dyes were investigated. The DSSCs based on dyes IS-BTh exhibited values of PCE in the range of 3.43–4.41 % under AM 1.5 G irradiation. The highest PCE value of 4.41 % (Jsc = 11.61 mA cm−2, Voc = 0.64 V, FF = 0.59) was achieved for DSSC based on dye IS-BTh-1, bearing thieno[3,2-b]indole as an electron-donating part. The temperature dependencies of the photovoltaic parameters for DSSC based on dye IS-BTh-1 were investigated.