Computational chemistry-assisted design of a non-fullerene acceptor enables 17.4% efficiency in high-boiling-point solvent processed binary organic solar cells

Abstract

Designing new high-performance non-fullerene acceptors is the key driving force for the development of organic solar cells (OSCs). In this work, a new acceptor, BOEH-4Cl, was designed based on the...

Selective halogenation of central and end-units of nonfullerene acceptors enables enhanced molecular packing and photovoltaic performance

“…Generally, Y-series NFAs are composed of an electron-rich ''donor-acceptor-donor (DA 0 D) 00 central core, electron-deficient terminal units, and stretched side chains. 16 Numerous strategies, including central subunit replacement (D or A 0 ), [21][22][23][24][25] endgroup modification, [26][27][28][29] and side-chain engineering, [17][18][19]30 were developed to optimize the properties of NFAs. Among these design strategies, halogenation (e.g., fluorination and chlorination) on NFAs has been proven to be an effective approach for improving their photovoltaic performance, 24,31,32 which contributes to (i) tuning the physicochemical properties (e.g., energy levels and absorption spectra); 33,34 (ii) decreasing energy loss; 35,36 and (iii) modulating molecular packing behaviors and crystallization and thus optimizing film morphology.…”

“…Generally, Y-series NFAs are composed of an electron-rich “donor–acceptor–donor (DA′D)′′ central core, electron-deficient terminal units, and stretched side chains. 16 Numerous strategies, including central subunit replacement (D or A′), 21–25 end-group modification, 26–29 and side-chain engineering, 17–19,30 were developed to optimize the properties of NFAs. Among these design strategies, halogenation ( e.g.…”

“…43,27.58, and 24.32 ns for Qx-o-4F, Qx-m-4F, and Qx-p-4Fbased devices, respectively), indicating its highest charge extraction ability. Meanwhile, the carrier lifetimes obtained from the TPV tests are 24.57, 27.51, 55.86, and 59.05 ms for Qx-o-4F, Qx-m-4F, Qx-p-4F, and Qx-p-4Cl-based devices, respectively (Fig.3h).…”

High photogeneration and low recombination rate leading to high-performance non-fullerene organic solar cells

“…Benefiting from the rapid development of non-fullerene electron acceptors (NFAs), the performance of OSCs continues to improve, with record power conversion efficiency (PCE) of over 19% reported recently. 1 Compared to fullerene-based devices, NFA-based devices not only broaden the absorption spectrum for enhanced short-circuit current ( J sc ), but also exhibit much lower energy loss 2,3 to yield particularly high open-circuit voltage ( V oc ) outputs. In an attempt to improve charge transport in OSCs, the fill factor (FF) of the resultant devices has been promoted to more than 80%, 4,5 suggesting that the competition between charge extraction and recombination 6 (also considered as the ratio of carrier drift or diffusion lengths to thickness) 7 is a key issue to overcome for high efficiency.…”

Triphenylamine side chain enabled polybenzodithiophene wide-bandgap donors for efficient organic solar cells

“…24–27 When the most promising electron-deficient building blocks such as dithieno[3,2:3,4;2,3:5,6]-benzo[1,2- c ][1,2,5]thiadiazole (DTBT), [7 c ]benzo[1,2- c :4,5- c ′]-dithiophene-4,8-dione (BDD), thieno-[3,4- c ]pyrrole-4,6-dione (TPD), and pyrrolo[3,4- f ]benzotriazole5,7-dione (TzBI) are combined with BDT, it enables PCEs of over 15% for the corresponding polymers (PM6, D18, J101 and PTB7). 28–37 However, we are intrigued to know whether constructing two-dimensional (2-D) conjugated polymers is an effective way of developing high-performance donor materials besides this linear D–A design concept. We first reported two-dimensional polyfluorenes bearing thienylenevinylene π-bridge–acceptor side chains for photovoltaic solar cells and the 2-D structures facilitated the isotropic charge transport of polymers compared to the linear fluorine-based polymer.…”