Building-up an interrelationship between isomeric benzyl inner side chains within nonfullerene acceptors and isomeric xylene solvents for non-chlorinated solvent-processed organic solar cells

Abstract

The side-chain engineering of A-DA'D-A-type nonfullerene acceptors (NFAs), well-known as Y6 series, is an efficient approach for retaining the physical properties of Y6-series but allowing manipulation of the solubility, crystallization,...

Eco-Friendly Solvent-Processed Dithienosilicon-Bridged Carbazole-Based Small-Molecule Acceptors Achieved over 25.7% PCE in Ternary Devices under Indoor Conditions

“…By comparison, PM7:DTSiC-2M- and PM7:DTSiCODe-4F-based binary blends display a relatively smooth roughness with R q values of 3.29 and 1.78 nm, respectively. The higher R q values indicate stronger crystalline nature and large domain size of blend morphology, better exciton dissociation, enhanced phase separation, and increased charge transfer, which contribute to improved J sc and FF. ,− From the phase and three-dimensional (3D) topological images of DTSiC-4F-based binary/ternary blends, the defined phase separation of the donors and acceptors with compact interpenetrating frameworks can be observed.…”

“…In the film state (Figure 2b), all molecules show bathochromic absorption with the maximum absorption peaks of DTSiC-4F, DTSiC-2M, and DTSiCODe-4F at 718, 666, and 690 nm, respectively, indicating intensified intermolecular π−π packing. 33,46,47 In detail, due to the weak ICT effect between the methylated end group and central backbone, DTSiC-2M shows a weak intermolecular π−π packing in the film state compared with other NFAs. The DTSiC-4F thin film shows an 80 nm bathochromic shift from the solution compared with DTSiCODe-4F.…”

Isomerization strategy on a non-fullerene guest acceptor for stable organic solar cells with over 19% efficiency

“…21,22 Currently, the isomerization of Y6-derivatives has become an effective way to improve the performance of binary OSCs. [23][24][25] In particular, almost all the Y6-derivatives have been developed by employing isomeric endcapping groups or side chains, [26][27][28][29][30] but the isomerization of the central electron-deficient core in Y6-derivatives has never been investigated or reported. In addition, the low glass transition temperatures (T g ) and high diffusion properties of the Y6-derivatives lead to unstable morphologies in blend films.…”

Conformational Locking Control of 2D Outer Side Chains via Fluorine Atom Positioning for Improving the Thermal Stability of Organic Solar Cells

“…Since this pioneering work, considerable progress has been made in the design and synthesis of molecular structures toward superior Y-series NFAs. ,, Side-chain engineering is one of the most efficient strategies for fine-tuning NFAs. − Y-series NFAs possess two sets of alkyl side chains, with the inner pair located on the pyrrole rings and the outer pair flanking at the 2-positions of the thienothiophene moieties . The inner and/or outer alkyl chain alterations, such as the chain length and branching point modifications, affect the blend morphologies and phase separation/mixing properties which are directly correlated to charge separation/transfer efficiencies, in addition to the material solubility. , Moreover, replacing the alkyl chain with a two-dimensional (2D) alkylaryl group on the outer position affects the molecular backbone geometry and improves the photovoltaic parameters of Y-series NFAs because of steric hindrance and conformational locking between the core group (DA′D) and the end groups (A). ,− Optimization of the molecular structure of Y-series NFAs resulted in PCEs surpassing 18% for OSCs composed of wide-band-gap donor polymers and Y-series NFAs. ,,− …”

“…17 The inner and/or outer alkyl chain alterations, such as the chain length and branching point modifications, affect the blend morphologies and phase separation/mixing properties which are directly correlated to charge separation/transfer efficiencies, in addition to the material solubility. 15,18 Moreover, replacing the alkyl chain with a two-dimensional (2D) alkylaryl group on the outer position affects the molecular backbone geometry and improves the photovoltaic parameters of Y-series NFAs because of steric hindrance and conformational locking between the core group (DA′D) and the end groups (A). 17,19−2324 Optimization of the molecular structure of Yseries NFAs resulted in PCEs surpassing 18% for OSCs composed of wide-band-gap donor polymers and Y-series NFAs.…”