Nonfused Ring Electron Acceptors for Ternary Polymer Solar Cells with Low Energy Loss and Efficiency Over 18.

Ternary polymer solar cells(PSCs) have been identified as an effective approach to improving power conversion efficiency (PCE) of binary PSCs. However, most of the third component, especially Y-series non-fullerene acceptors, is a fused ring acceptor which often requires a rather tedious synthesis and the use of hazardous organostannane reagents. In this work, two nonfused ring acceptors IOEH-4F and IOEH-N2F are synthesized by a green synthetic route and incorporated into PM6:Y6 blend. Encouragingly, the IOEH-4F and IOEH-N2F-based ternary PSCs exhibited more efficient charge transfer, exciton separation, and lower energy loss than PM6:Y6-based PSCs. And the IOEH-4F and IOEH-N2F-based ternary PSCs achieved an impressive PCE of 17.80% and 18.13%, respectively, which are higher than that of PM6:Y6 based PSCs (16.18%). Notably, these PCE values are also the highest PCEs for ternary PSCs including non-fused ring acceptors. Importantly, even when the IOEH-N2F:Y6 ratios increased from 0.05:1.2 to 0.50:1.2, the PCE of IOEH-N2F-based ternary PSCs (16.70%) are still higher than that of PM6:Y6 based PSCs, indicating the great potential for cost saving. It is believed that the findings will help the design of better nonfused ring acceptors and the optimization of corresponding ternary PSCs with cost-saving advantage.

[Study on effect of hyperbranched polyester on the mechanical properties and morphology of PEG polyurethane elastomer by ATR-FTIR].

In order to enhance the mechanical properties of polyethylene glycol (PEG) polyurethane elastomer, the modified hyperbranched polyester (HBP) was introduced. The chemical structures of HBP/PEG polyurethane films were analyzed by attenuated total reflection-Fourier transfoum infrared spectrum (ATR-FTIR). The results indicate that with the modified hyperbranched polyester added, the tensile strength and elongation at break of PEG polyurethane elastomer are improved obviously. When the content of hyperbranched polyester of the third generation is 0.4%, the resultant elastomer has the best tensile strength, which increases 2.53 times. When the content of hyperbranched polyester of the first generation rises up to 1.6%, the resultant elastomer has the best elongation at break, which increases 1.43 times. The degree of the total hydrogen bonding and the degree of microphase separation are increased, which enhance the mechanical properties of PEG polyurethane elastomer.

Simple-Structured NIR-Absorbing Small-Molecule Acceptors with a Thiazolothiazole Core: Multiple Noncovalent Conformational Locks and D-A Effect for Efficient OSCs.

Developing simple-structured and efficient near-infrared (NIR) absorbing small-molecule acceptors (SMAs) remains of great importance for commercial applications in organic solar cells (OSCs). Herein, we construct two novel thiazolothiazole-centered NIR-absorbing SMAs by alkoxy/alkylthio side chains (TTz3/TTz4) and multiple noncovalent conformational locks of S···N, S···O, and S···S. These conformational locks make both simple-structured SMAs exhibit an extended planar configuration and a red-shifted NIR absorption in comparison with the SMA with an alkyl side chain (TTz1). As expected, both SMAs show high-efficiency photovoltaic performance in the solution-processing OSCs using J71 as a donor. A higher power conversion efficiency of 8.76% with a low energy loss (0.57 eV) is obtained in the TTz3-based OSCs. It is the first report on the simple-structured and efficient NIR-absorbing SMAs, which have great potential applied in the semitransparent OSCs.