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Developing a high-performance donor polymer is critical for achieving efficient non-fullerene organic solar cells (OSCs). Currently, most high-efficiency OSCs are based on a donor polymer named PM6, unfortunately, whose performance is highly sensitive to its molecular weight and thus has significant batch-to-batch variations. Here we report a donor polymer (named PM1) based on a random ternary polymerization strategy that enables highly efficient non-fullerene OSCs with efficiencies reaching 17.6%. Importantly, the PM1 polymer exhibits excellent batch-to-batch reproducibility. By including 20% of a weak electron-withdrawing thiophene-thiazolothiazole (TTz) into the PM6 polymer backbone, the resulting polymer (PM1) can maintain the positive effects (such as downshifted energy level and reduced miscibility) while minimize the negative ones (including reduced temperature-dependent aggregation property). With higher performance and greater synthesis reproducibility, the PM1 polymer has the promise to become the work-horse material for the non-fullerene OSC community.

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Traditional pharmacotherapy suffers from multiple drawbacks that hamper patient treatment, such as the buildup of antibiotic resistances or low drug selectivity and toxicity during systemic application. To overcome these challenges, drug activity can be controlled by employing delivery, targeting, or release solutions that mostly rely on the response to external physicochemical stimuli. Due to various technical limitations, mechanical force as a stimulus in the context of polymer mechanochemistry has so far not been used for this purpose, yet it has been proven to be a convenient and robust method to site-selectively rearrange or cleave bonds with submolecular precision in the realm of materials chemistry. Here, we present an unprecedented mechanochemically responsive system capable of successively releasing small furan-containing molecules, including the furylated fluorophore dansyl and the drugs furosemide as well as furylated doxorubicin, by ultrasound-induced selective scission of disulfide-centered polymers in solution. We show that mechanochemically generated thiol-terminated polymers undergo a Michael-type addition to Diels–Alder (DA) adducts of furylated drugs and acetylenedicarboxylate derivatives, initiating the downstream release of the small molecule drug by a retro DA reaction. We believe that this method can serve as a blueprint for the activation of many other small molecules.

The rapid development of organic synthetic chemistry has led to an extraordinary diversity in the structure and properties of organic semiconductor materials. [1][2][3][4] It is widely accepted that a subtle structural change is able to lead to dramatic property Generally, highly efficient organic solar cells require both a high open-circuit voltage (V OC ) and a high short-circuit current density (J SC ). Reducing the energy loss (E loss ) is an effective way to achieve a high V OC without compromising the photocurrent, which is ideal for enhancing the power conversion efficiencies (PCEs). Herein, a new chlorinated nonfullerene acceptor (ITC-2Cl) with chlorinated thiophene-fused end groups is developed. In comparison with the unchlorinated counterpart (ITCPTC), the introduction of Cl improves not only the electronic properties by redshifting the absorption spectra and deepening the lowest unoccupied molecular orbital energy levels, but also the molecular packing and thus thin-film morphology. The PM6:ITC-2Cl-based device yields a significantly higher PCE (13.6%) with a lower E loss (0.67 eV) than the ITCPTCbased device (PCE of 12.3% with E loss of 0.70 eV). More importantly, compared to the archetypal nonfullerene acceptors such as IT-4F (PCE of 12.9% with E loss of 0.73 eV) and IT-4Cl (PCE of 12.7% with E loss of 0.76 eV), the ITC-2Cl-based device shows a higher PCE and a lower E loss . These results demonstrate that the chlorinated thiophene-fused end group is a promising candidate for a highperformance nonfullerene acceptors with low energy loss.

Regulating molecular structure to optimize the active layer morphology is of considerable significance for improving the power conversion efficiencies (PCEs) in organic solar cells (OSCs). Herein, we demonstrated a simple ternary copolymerization approach to develop a terpolymer donor PM6‐Tz20 by incorporating the 5,5′‐dithienyl‐2,2′‐bithiazole (DTBTz, 20 mol%) unit into the backbone of PM6 (PM6‐Tz00). This method can effectively tailor the molecular orientation and aggregation of the polymer, and then optimize the active layer morphology and the corresponding physical processes of devices, ultimately boosting FF and then PCE. Hence, the PM6‐Tz20: Y6‐based OSCs achieved a PCE of up to 17.1% with a significantly enhanced FF of 0.77. Using Ag (220 nm) instead of Al (100 nm) as cathode, the champion PCE was further improved to 17.6%. This work provides a simple and effective molecular design strategy to optimize the active layer morphology of OSCs for improving photovoltaic performance.

We designed and synthesized a series of fused-ring electron acceptors (FREAs) based on fused octacyclic cores end-capped by 3-(1,1-dicyanomethylene)-5,6-difluoro-1-indanone (NOICs) using a bottom-up approach. The NOIC series shares the same end groups and side chains, as well as similar fused-ring cores. The butterfly effect, arising from the methoxy positions in the starting materials, impacts the design of the final FREAs, as well as their molecular packing, optical and electronic properties, charge transport, film morphology and performance of organic solar cells. The binary-blend devices based on this NOIC series show power conversion efficiencies varying from 7.15% to 14.1%, due to the different intrinsic properties of the NOIC series, morphologies of blend films, and voltage losses of devices.

A new narrow bandgap polymer acceptor (PN1) based on a fused-ring small molecule acceptor as the core building block was designed and developed. The optimal all-polymer solar cell based on the blend of PM6 and PN1 achieved an outstanding power conversion efficiency of 10.5% with a high open-circuit voltage of 1.0 V, a short circuit current density of 15.2 mA cm−2 and a fill factor of 0.69.