Organic polymeric and small molecular electron acceptors for organic solar cells

Publication date: Available online 20 February 2018 Source:Materials Science and Engineering: R: Reports Author(s): Venkateswararao A., Shun-Wei Liu, Ken-Tsung Wong In organic solar cells (OSCs), the electron donor (D) and electron acceptor (A) blended active layer is the most crucial component for governing the power conversion efficiency (PCE). Various efficient donor materials with wide structural variations have been developed to couple with high-electron mobility fullerene-based acceptors, giving PCEs beyond 12%. However, fullerene-embedded OSCs encounter great challenges of low flexibility for structural modifications, poor absorption and blend morphological stability. The demand for alternative acceptors drives current OSC research towards non-fullerene acceptors (NFAs). Tailor-made NFAs of polymer or small molecule (SM) can typically exhibit tunable optical and electrochemical properties, high solubility, air stability, and favorable intermolecular interactions leading to compact packing and good nano-phase segregation in the active blend. In this review, we systematically depict the effects of molecular structures on the physical properties and device performances. The promising/most popular cores and general molecular design strategies of NFAs are outlined. The polymeric and SM NFAs were classified into several sub-groups based on their structural features, and in every sub-group, the structural evolution, current status, the champion case as well as the future...
Source: Materials Science and Engineering: R: Reports - Category: Materials Science Source Type: research