Effect of semi-perfluoroalkyl chains on A-DA′D-A type small molecule acceptor in organic solar cells

Herein, a new A-DA′D-A structured small molecule acceptor named m-TF₉, containing semi-perfluoroalkyl chains, was designed and synthesized for highly efficient organic solar cells (OSCs). Compared with its alkylsubstituted analogous m-TH, m-TF₉ exhibits tighter molecular packing and lower surface free energy. When blended with PTQ10, m-TF₉ can achieve a high fill factor of 77.3%. By using 1,4-difluorobenzene as an additive, the PTQ10:m-TF₉-based OSC delivers a high efficiency of 16.3% with an improved short circuit current (J_SC) of 27.0 mA cm⁻². In addition, the m-TF₉-based OSC demonstrates good storage stability in both air and nitrogen environments. This work highlights the great potential of semi-perfluoroalkyl chains as the modification blocks for A-DA′D-A type acceptors to achieve good charge transport properties and high efficiency.