A new BODIPY dimer containing carbazole group as a small molecule donor for ternary organic solar cells with the PCE up to 14.97%

The investigation of donor based on small molecules as the active component of bulk-heterojunction organic solar cells (BHJ-OSCs) continues to attract great attention due to their advantages over polymer solar cells . Herein, we report the synthesis and solar cell fabrication of small molecule donors based on BODIPY dimer. The BODIPY dimer features thiophene and carbazole groups as donor units attached to the α and β-positions of the BODIPY core and dicyanodistyryl group as bridging group, and which is named as DI-BDP-CZ and s howing complementary absorption with PC 71 BM and Y6 . The electrochemical research results indicate that the frontier energy levels of DI-BDP-CZ (HOMO = −5.55 eV and LUMO = −3.83 eV) is well matched with energy levels of both PC 71 BM and Y6 . The photovoltaic performance of DI-BDP-CZ used as electron-donors along with PC 71 BM or Y6 as acceptor was evaluated in bulk heterojunction organic solar cells . The OSCs based on optimized DI-BDP-CZ : PC 71 BM and DI-BDP-CZ : Y6 attained overall PCE of 7.63% and 12.58%, respectively. After the optimization of the active layer, the ternary organic solar cells based on DI-BDP-CZ : PC 71 BM:Y6 can achieve overall power conversion efficiency (PCE) as high as 14.97%, which is higher than the corresponding binary organic solar cells. The higher PCE of the ternary OSC is ascribed to the efficient exciton dissociation, balanced charge transport, better crystallinity and appropriate phase separation. A new BODIPY dimer containing carbazole group named as DI-BDP-CZ as a small molecule donor is well matched with both PC 71 BM and Y6 . The ternary OSCs based on optimized DI-BDP-CZ : PC 71 BM : Y6 attained PCE up to 14.97% (J SC = 23.84 mA/cm 2 and V OC = 0.86 V). • A new D-A type BODIPY dimer, DI-BDP-CZ , was prepared as an efficient small molecule donor for organic solar cell. • The binary blended organic solar cells based on DI-BDP-CZ as electron donors were fabricated. • A high-power conversion efficiency (PCE) of 14.97% was achieved with addition of PC 71 BM into DI-BDP-CZ : Y6 system. • The reason of the higher PCE for the ternary OSCs was clarified.