Thieno[3,2-b]indole-benzo[b]thieno[2,3-d]thiophen-3(2H)-one-based D-π-A molecules as electron transport materials for perovskite solar cells

Four new compounds ISC 1-4 with a D-π-A structure, containing thieno[3,2-b]indole as an electron-donating unit and benzo[b]thieno[2,3-d]thiophen-3(2H)-one as an electron-accepting unit, were readily synthesized using a simple three-step protocol. The thermal stability, and optical and electronic properties of these materials were investigated. In thin solid films of ISC 1-4, the electron mobility measured using the conventional CELIV technique was in the range of 10⁻⁶ cm² V⁻¹ s⁻¹. The ISC 1-3 substances were found to be applicable as electron transport materials for perovskite solar cells. For the ISC 1 based PSC, the power conversion efficiency of 12.02% was demonstrated under AM 1.5 G irradiation.