Non‐fullerene all‐small‐molecule organic solar cells (NFSM‐OSCs) have shown potential as OSCs, owing to their high purity, easy synthesis and good reproducibility. However, challenges in the modulation of phase separation morphology have limited their development. Herein, two novel small molecular donors, BTEC‐1F and BTEC‐2F, derived from the small molecule DCAO3TBDTT, are synthesized. Using Y6 as the acceptor, devices based on non‐fluorinated DCAO3TBDTT showed an open circuit voltage (Voc) of 0.804 V and a power conversion efficiency (PCE) of 10.64 %. Mono‐fluorinated BTEC‐1F showed an increased Voc of 0.870 V and a PCE of 11.33 %. The fill factor (FF) of di‐fluorinated BTEC‐2F‐based NFSM‐OSC was improved to 72.35 % resulting in a PCE of 13.34 %, which is higher than that of BTEC‐1F (61.35 %) and DCAO3TBDTT (60.95 %). To our knowledge, this is the highest PCE for NFSM‐OSCs. BTEC‐2F had a more compact molecular stacking and a lower crystallinity which enhanced phase separation and carrier transport.

Non-fullerene all-small-molecule organic solar cells (NFSM-OSCs) have shown potential as OSCs,o wing to their high purity,easy synthesis and good reproducibility.However, challenges in the modulation of phase separation morphology have limited their development. Herein, two novel small molecular donors,B TEC-1F and BTEC-2F,d erived from the small molecule DCAO3TBDTT,are synthesized. Using Y6 as the acceptor,d evices based on non-fluorinated DCAO3TBDTT showed an open circuit voltage (V oc )o f 0.804 Vand ap ower conversion efficiency (PCE) of 10.64 %. Mono-fluorinated BTEC-1F showed an increased V oc of 0.870 Va nd aP CE of 11.33 %. The fill factor (FF) of difluorinated BTEC-2F-based NFSM-OSC was improved to 72.35 %r esulting in aP CE of 13.34 %, whichi sh igher than that of BTEC-1F (61.35 %) and DCAO3TBDTT (60.95 %).To our knowledge,t his is the highest PCE for NFSM-OSCs. BTEC-2F had amore compact molecular stackingand alower crystallinity which enhanced phase separation and carrier transport.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

A novel polymer was used as the donor material in organic solar cells to achieve the best photovoltaic performance based on DTBDT.