Development of non-fullerene electron acceptors for efficient organic photovoltaics

Abstract

Compared to fullerene based electron acceptors, n-type organic semiconductors, so-called non-fullerene acceptors (NFAs), possess some distinct advantages, such as readily tuning of optical absorption and electronic energy levels, strong absorption in the visible region and good morphological stability for flexible electronic devices. The design and synthesis of new NFAs have enabled the power conversion efficiencies (PCEs) of organic photovoltaic (OPV) devices to increase to around 19%. This review summarises the important breakthroughs that have contributed to this progress, focusing on three classes of NFAs, i.e. perylene diimide (PDI), diketopyrrolopyrrole (DPP) and acceptor–donor–acceptor (A-D-A) based NFAs. Specifically, the PCEs of PDI, DPP, and A-D-A series based non-fullerene OPVs have been reported up to 11%, 13% and 19%, respectively. Structure–property relationships of representative NFAs and their impact on OPV performances are discussed. Finally, we consider the remaining challenges and promising directions for achieving high-performing NFAs.

A comparison of para, meta, and ortho-carborane centred non-fullerene acceptors for organic solar cells

“…The acceptor-donoracceptor (A-D-A) molecular architecture has proven hugely successful and has become a leading design strategy towards highperforming NFAs, encompassing a central electron rich core flanked by two electron deficient end-groups. [50][51][52][53][54] The indacenodithiophene (IDT) core is one of the most widely employed electron donating moieties for such compounds. 55 Commonly occurring examples include IDIC, IDTBR, and IEIC and their many derivatives, as well as ITIC employing a structurally similar indacenodithienothiophene (IDTT) core.…”

All slot-die coated organic solar cells using an amine processed cathode interlayer based upon an amino acid functionalised perylene bisimide

“…[5][6][7][8] Furthermore, lab-scale OPV devices with power conversion efficiencies (PCEs) of up to 18% have been reported, which paves the way for future commercialisation. [9][10][11] However, further work to improve performance, lifetime, and processing is needed for this technology to become widespread in commercial applications.…”

A novel selenophene based non-fullerene acceptor for near-infrared organic photodetectors with ultra-low dark current

“…Small molecule NFAs show numerous attractive features, including high purity, crystallinity and lower reorganizational energy. [12][13][14][15][16] Furthermore, the bandgap and energy levels can be readily tuned by varying the synthetic structure in order to achieve near-infrared light absorption. [17][18][19][20] Numerous NFAs have been reported to date, with a popular design motif based on an electron-rich donor (D) core being flanked by two electron-deficient acceptor (A) units, the socalled A-D-A system.…”

“…Small molecule NFAs show numerous attractive features, including high purity, crystallinity and lower reorganizational energy. 12–16 Furthermore, the bandgap and energy levels can be readily tuned by varying the synthetic structure in order to achieve near-infrared light absorption. 17–20…”