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Comprehensive Summary: By employing the asymmetric end‐group engineering, an asymmetric nonfused‐ring electron acceptor (NFREA) was designed and synthesized. Compared with the symmetric analogs (NoCA‐17 and NoCA‐18), NoCA‐19 possesses broader light absorption range, more coplanar π‐conjugated backbone, and appropriate crystallinity according to the experimental and theoretical results. The organic solar cells based on J52:NoCA‐19 exhibited a power conversion efficiency as high as 12.26%, which is much higher than those of J52:NoCA‐17 (9.50%) and J52:NoCA‐18 (11.77%), mainly due to more efficient exciton dissociation, better and balanced charge mobility, suppressed recombination loss, shorter charge extraction time, longer charge carrier lifetimes, and more favorable blend film morphology. These findings demonstrate the great potential of asymmetric end‐group engineering in exploring low‐cost and high‐performance NFREAs. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: By employing thiazole and 4‐chlorothiazole as the A′ units, two A‐D‐A′‐D‐A type nonfused‐ring electron acceptors (NFREAs) Tz‐H and Tz‐Cl were designed and synthesized. Replacing thiazole in Tz‐H with 4‐chlorothiazole can not only remarkably shorten the synthetic route through C—H direct arylation but also enhance molecular planarity with the simultaneous incorporation of S···N and S···Cl noncovalently conformational locks (NoCLs). The photovoltaic devices based on PM6:Tz‐Cl exhibited a power conversion efficiency as high as 11.10%, much higher than that of PM6:Tz‐H (6.41%), mainly due to more efficient exciton dissociation, better and more balanced carrier mobility, less charge recombination, and more favorable morphology. These findings demonstrate the great potential of NoCLs in achieving low‐cost and high‐performance NFREAs. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: By employing thiazole and 4‐chlorothiazole as the A′ units, two A‐D‐A′‐D‐A type nonfused‐ring electron acceptors (NFREAs) Tz‐H and Tz‐Cl were designed and synthesized. Replacing thiazole in Tz‐H with 4‐chlorothiazole can not only remarkably shorten the synthetic route through C—H direct arylation but also enhance molecular planarity with the simultaneous incorporation of S···N and S···Cl noncovalently conformational locks (NoCLs). The photovoltaic devices based on PM6:Tz‐Cl exhibited a power conversion efficiency as high as 11.10%, much higher than that of PM6:Tz‐H (6.41%), mainly due to more efficient exciton dissociation, better and more balanced carrier mobility, less charge recombination, and more favorable morphology. These findings demonstrate the great potential of NoCLs in achieving low‐cost and high‐performance NFREAs. [ABSTRACT FROM AUTHOR]

Fluorination exhibits multiple effects on the photophysical properties of conjugated copolymers and has attracted enormous attention in organic solar cells (OSCs). Herein, a series of structurally identical benzo[1,2-c:4,5-c′]dithiophene-4,8-dione (T1) based polymers (named PPhF0-T1 to PPhF4-T1) with different numbers of fluorine substitutions have been designed and synthesized. With the number of fluorine substitution increases, the energy levels of the polymers decrease gradually. ITPTC non-fullerene acceptor was employed to fabricate OSCs with these polymers. We found that the introduction of fluorine can effectively improve the open-circuit voltage of the device. Upon one or two fluorine atoms are appended to the polymer, the corresponding short-circuit currents (J sc s) are obviously promoted. However, due to the excessive phase separation and hence suppressed charge carrier mobility, the J sc decreases when there are four fluorine atoms in the polymer. Consequently, without any additives, the PPhF2-T1 based device gives the highest power conversion efficiency of 10.61%, which is much higher than that of nonfluorinated polymer based OSC (3.97%). This work presents a systematic study upon the effect of different numbers of fluorine atoms on the photovoltaic performance of OSCs, which may serve as a useful guideline in the design of efficient conjugated polymers. To investigated the effect of fluorination on the performance of T1 copolymers. We designed and synthesized four copolymers by altering the numbers of fluorine atoms on the benzene group (named PPhF0-T1 to PPhF4-T1). When one or two F atoms are introduced to the polymers, the PCEs of OSCs are significantly improved. PPhF2-T1:ITCPTC based device delivers a highest PCE of 10.61%, while PPhF4-T1 based OSC yields a relatively lower PCE of 6.28%. Image 1 • Different numbers of fluorine substitutions controllable conjugated polymers were synthesized. • Substitution effects of amount of fluorine atoms on the photovoltaic performance were systematically investigated. • Multiple understanding the fluorination would be better for development of high-performance polymer donor materials. [ABSTRACT FROM AUTHOR]