Direct arylation polycondensed conjugated polyelectrolytes as universal electron transport layers for highly efficient polymer solar cells†
We demonstrate a series of direct arylation polycondensed conjugated polyelectrolytes (CPEs) for application in universal and thickness-insensitive electron transport materials (ETMs) of highly efficient polymer solar cells (PSCs). The energy levels, absorption spectra, and self-doping behaviors of these CPEs are altered by the substituted alkyl and alkoxy ammonium side chains. PSCs with three donor:acceptor combinations as active layers are examined and the results indicate that these CPEs are capable of achieving high efficiency for both fullerene PSCs and non-fullerene PSCs. The excellent capability of CPEs for interface modification achieves high-performance PM6:Y6-based PSCs with a PCE of over 16%. Moreover, the high electron mobilities of these CPEs endow them with high performance at thicknesses ranging from 10 nm to 100 nm, indicating that these CPEs are good candidates as universal and thickness-insensitive ETMs for PSCs.