Renewed Prospects for Organic Photovoltaics.

Organic photovoltaics (OPVs) have progressed steadily through three stages of photoactive materials development: (i) use of poly-(3-hexylthiophene) and fullerene-based acceptors (FAs) for optimizing bulk heterojunctions; (ii) development of new donors to better match with FAs; (iii) development of non-fullerene acceptors (NFAs). The development and application of NFAs with an A–D–A configuration (where A = acceptor and D = donor) has enabled devices to have efficient charge generation and small energy losses (Eloss < 0.6 eV), resulting in substantially higher power conversion efficiencies (PCEs) than FA-based devices. The discovery of Y6-type acceptors (Y6 = 2,2′-((2Z,2′Z)-((12,13-bis-(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]-thiadiazolo-[3,4-e]-thieno-[2″,3″:4′,5′]-thieno-[2′,3′:4,5]-pyrrolo-[3,2-g]-thieno-[2′,3′:4,5]-thieno-[3,2-b]-indole-2,10-diyl)-bis-(methanylylidene))-bis-(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))-dimalononitrile) with an A–DA′ D–A configuration has further propelled the PCEs to go beyond 15% due to smaller Eloss values (∼0.5 eV) and higher external quantum efficiencies. Subsequently, the PCEs of Y6-series single-junction devices have increased to >19% and may soon approach 20%. This review provides an update of recent progress of OPV in the following aspects: developments of novel NFAs and donors, understanding of the structure–property relationships and underlying mechanisms of state-of-the-art OPVs, and tasks underpinning the commercialization of OPVs, such as device stability, module development, potential applications, and high-throughput manufacturing. Finally, an outlook and prospects section summarizes the remaining challenges for the further development of OPV technology. [ABSTRACT FROM AUTHOR]