Bulk Heterojunction organic solar cells (BHJ-OSCs) are promising for solar energy conversion due to mechanical flexibility, low cost and the possibility to be fabricated by printing on plastic substrates. The BHJ-OSC photoactive layer consists of a blend of an electron acceptor and an electron donor semiconductors converting exitons to charge carriers. Traditionally, fullerenes have been used as acceptors, however, since the discovery of the ITIC/IDIC small-molecule families, these non fullerene acceptors (NFAs) have enabled OSCs with dramatically increase performance. Despite these accomplishments, several issues remain for NFA-based OSCs such as morphological instability, which translates into performance deterioration, and poor mechanical properties. An interesting strategy to address these problems has been to incorporate NFA units into polymeric backbones. Here we report the synthesis of several novel NFA-based polymers achieved via direct arylation polycondensation (DARP) reactions. Our donor-acceptor polymers consist of an anthradithiophene donor unit (M1) and a ITIC/IDIC/Y6 polymerizable acceptor unit (M2) have been obtained by different DARP protocols, optimized for each polymer. M1 was obtained with a very low E-Factor via a cascade direct arylation/cross aldolization reaction starting from inexpensive starting materials. The dibrominated ITIC/IDIC/Y6 M2 units are commercially available or were synthesized via known protocols.

Synthesis of novel electron acceptor polymers for organic solar cells via DARP

ACS Fall 2021

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