Light absorption in the near-infrared region of the non-fullerene acceptors is important for the improvement of power conversion efficiency (PCE) of organic solar cells. To utilize the near-IR region, reducing the band gap of NFAs is the basic strategy, and as a result, short-circuit current density (JSC) and PCE can be improved. Herein, we synthesized new selenophene-based acceptors, TSe-4F and TSe- 4Cl from modifying the acceptor BTP-eC9 (TS-4Cl). We substituted thieno[3,2-b]thiophene attached on the 2,1,3-benzothiadiazole unit to selenopheno[3,2-b]thiophene, and the band gap reduced from 1.36 eV to 1.33 and 1.32 eV for TSe-4F and TSe-4Cl, respectively. Furthermore, we studied the impact of end-group by comparing TSe-4F and TSe-4Cl, which has fluorine and chlorine atoms, respectively. By substituting the end-group to fluorine atoms, D18:TSe-4F showed an improvement of fill factor (FF) of 78.38%, and as a result, the PCE of D18:TSe-4F was 16.64%. The reason of improved FF was because of better charge extraction and collection processes.
Publisher
Ulsan National Institute of Science and Technology
Degree
Master
Major
School of Energy and Chemical Engineering (Energy Engineering)