Sustainable Energy & Fuels - October 2018

Thiophene-based p-type molecules are being extensively investigated and employed in optoelectronic
devices due to their intriguing semiconducting properties. Herein, we report the synthesis and
characterization of a 4H-cyclopenta[1,2-b:5,4-b0]dithiophene-based core, having methoxy-substituted
triphenylamine side arms as donor groups. These rationally designed molecules were obtained through
easy cross-coupling reactions, in few synthetic and purification steps. The synthesized molecules coded
as CDTh 1 and CDTh-EtHex 2 showed excellent thermal stability, and the fabricated perovskite solar
cells using CDTh 1 and CDTh-EtHex 2 as hole transporting materials (HTMs) gave competitive
performance compared to the state-of-the-art Spiro-OMeTAD. Photoluminescence of perovskite layers
coated with these HTMs show relatively high quenching suggesting the injection of holes from the
valence band of the perovskite into the HOMO of the HTM. The estimated production cost was
calculated and found to be a fraction of that of commercially available state-of-the-art Spiro-OMeTAD