Fullerene-free polymer solar cells processed from non-halogenated solvents in air with PCE of 4.8.

Progress towards practical organic solar cells amenable to large scale production is reported. Fullerene-free organic solar cells with a PCE of ∼4.8% are achieved based upon an active layer composed of the standard donor polymer PTB7-Th and a highly soluble twisted PDI acceptor tPDI-Hex. All devices can be fabricated and tested in air with 'as-cast' active layers being processed from the greener solvents o-xylene (or trimethyl benzene) or the eco-friendly and bio-derived solvent 2Me-THF without loss in efficiency.