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

摘要

A series of novel D-pi-A-pi-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 pi-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 (E-g) 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 BDCTFEBT based devices due to the double effect of TT-linkage and F-substitution. These results provide valuable information on design of novel PV materials. (C) 2015 Elsevier Ltd. All rights reserved.