Tailoring the photophysical and photovoltaic properties of boron-difluorodipyrromethene dimers

Five boron-difluorodipyrromethene (BODIPY) dimers have been designed and synthesized successfully via acid-catalysed condensation and Pd-catalysed cross-coupling reactions. The structural modification, including verifying the structures of the pi-bridges, altering the positions the bridges link (meso- or beta-positions), and regulating the molecular planarity, can modulate the photophysical properties and the aggregation behaviors of the five dimers efficiently. Solution-processed organic solar cells were fabricated to evaluate the photovoltaic properties of these molecules further either as acceptors or donors. When using as nonfullerene acceptor and blended with the polymer donor of PTB7, an open circuit voltaic (V-oc) of 1.12 and 1.08 V was achieved from the thiophene and benzodithiophene bridged BODIPY dimers, respectively. This V-oc is among the top values achieved from the non-fullerene organic solar cells so far. 2017 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.