Tuning the photovoltaic performance of BT-TPA chromophore based solution-processed solar cells through molecular design incorporating of bithiophene unit and fluorine-substitution

• Four novel D-π-A-π-D typed OSMs have been designed and synthesized for BHJ-OSCs.
• PV properties were tuned via molecular design incorporating of TT- and F-unit.
• A significantly increased Jsc was observed for BDCTTMBT with narrow Eg.
• A high Voc of 1.11 V was obtained for BDCTFBT due to F-effect with lowest HOMO.
• A best PCE was achieved for BDCTTFBT due to double effect of TT- and F-unit.

A series of novel D-π-A-π-D typed organic small molecules (OSMs) have been designed and synthesized successfully for solution-processed bulk-heterojunction (BHJ) solar cells, consisting of thiophene (T) or bithiophene (TT) as a segment of π-bridge, besides, incorporating benzothiadiazole (BT) or fluorinated benzothiadiazole (FBT) as the electron-withdrawing core (A), respectively. The photovoltaic (PV) performance was finely tuned via molecular design. A significantly increased short-circuit current density (Jsc) was observed for BDCTTMBT with narrow energy gap (Eg) due to the extended conjugation-length with TT-linkage, and a high open-circuit voltage (Voc) of 1.11 V was obtained for BDCTFBT due to the F-substitution with the lowest highest occupied molecular orbital (HOMO). Among them, a best power conversion efficiency (PCE) of 4.86% was achieved for BDCTTFBT based devices due to the double effect of TT-linkage and F-substitution. These results provide valuable information on design of novel PV materials.

A series of novel D-π-A-π-D typed OSMs have been designed and synthesized successfully for solution-processed BHJ solar cells. The PV performance was finely tuned via molecular design. A significantly increased Jsc was observed for BDCTTMBT with narrow Eg due to the extended conjugation-length with TT-linkage, and a high Voc of 1.11 V was obtained for BDCTFBT due to the F-substitution with the lowest HOMO. Among them, a best PCE of 4.86% was achieved for BDCTTFBT based devices due to the double effect of TT-linkage and F-substitution, which is among the best performance for BT-TPA based BHJ OSMs-SCs ever reported to date. These results provide valuable information on the design of novel PV materials.Figure optionsDownload as PowerPoint slide