A Three‐dimensional Non‐fullerene Small Molecule Acceptor for Solution‐processed Organic Solar Cells

An acceptor-donor-acceptor (A-D-A) three-dimensional (3D) small molecule acceptor (SFTTIC), using spirobifluorene as the core unit linking with four thieno[3,2-b]thiophenes (TT) and end-capped with 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (INCN) was developed for solution processed organic solar cells. SFTTIC has a high absorption coefficient up to 3.12 × 105 mol-1 cm-1, good thermal stability and appropriate energy levels. The optimized power conversion efficiency (PCE) of 5.66% and 4.65% were achieved for the devices with PBDB-T:SFTTIC and PTB7-Th:SFTTIC, respectively.