Herein we study the effects of borane incorporation in a perylene diimide (PDI)-based non-fullerene acceptor (NFA). We have previously demonstrated that a PDI-bithiophene-PDI ((PDI) 2 Th 2 ) compound can be synthesized via direct (hetero)arylation techniques and is easily modified to incorporate a phosphole in the bithiophene core ((PDI) 2 Th 2 PO) to tune the electronic and geometric properties. In this work, we have synthesized the borane analogue ((PDI) 2 Th 2 B) and demonstrated that the organoboron moiety heavily influences the optical, electronic, and geometric properties. To determine the effects of borane functionalization on device performance, green solvent solution-processed bulk-heterojunction solar cells were fabricated using a medium-gap donor polymer TTFQx-T1 and each PDI compound as the NFA, respectively. Devices with the new borane-containing compound provided the highest efficiency, more than twice that for the other compounds, which was attributed to a highly twisted structure allowing for a more favorable active-layer morphology to be formed.

A new n-type p-π* conjugated organic molecule based on triarylborane shows unique alcohol-solubility even in the absence of polar side chains. With its low-lying LUMO/HOMO energy levels and high electron mobility, the molecule can be used as electron acceptor in eco-friendly alcohol-processed organic solar cells.