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The structure of molecular aggregates is crucial for charge transport and photovoltaic performance in organic solar cells (OSCs). Herein, the intermolecular interactions and aggregated structures of nonfused‐ring electron acceptors (NFREAs) are precisely regulated through a halogen transposition strategy, resulting in a noteworthy transformation from a 2D‐layered structure to a 3D‐interconnected packing network. Based on the 3D electron transport pathway, the binary and ternary devices deliver outstanding power conversion efficiencies (PCEs) of 17.46 % and 18.24 %, respectively, marking the highest value for NFREA‐based OSCs. [ABSTRACT FROM AUTHOR]

A novel polymer donor (PBDTS-Se) is designed to match with a non-fullerene acceptor (SdiPBI-S). The corresponding solar cells show a high efficiency of 8.22%, which result from synergetic improvements of light harvesting, charge carrier transport and collection, and morphology. The results indicate that rational design of novel donor materials is important for non-fullerene organic solar cells.

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]

Morphological stability is crucially important for the long‐term stability of polymer solar cells (PSCs). Many high‐efficiency PSCs suffer from metastable morphology, resulting in severe device degradation. Here, a series of copolymers is developed by manipulating the content of chlorinated benzodithiophene‐4,8‐dione (T1‐Cl) via a random copolymerization approach. It is found that all the copolymers can self‐assemble into a fibril nanostructure in films. By altering the T1‐Cl content, the polymer crystallinity and fibril width can be effectively controlled. When blended with several nonfullerene acceptors, such as TTPTT‐4F, O‐INIC3, EH‐INIC3, and Y6, the optimized fibril interpenetrating morphology can not only favor charge transport, but also inhibit the unfavorable molecular diffusion and aggregation in active layers, leading to excellent morphological stability. The work demonstrates the importance of optimization of fibril network morphology in realizing high‐efficiency and ambient‐stable PSCs, and also provides new insights into the effect of chemical structure on the fibril network morphology and photovoltaic performance of PSCs. [ABSTRACT FROM AUTHOR]

Abstract π-Bridges play a crucially important role in determining the optical absorption, bandgap and energy levels of donor-π-acceptor-π type conjugated polymers. In this contribution, a new polymer donor named PBT1-C-2Cl is synthesized by inserting the chlorine atoms onto π-bridges of the polymer PBT1-C. The introduction of chlorine atoms enables PBT1-C-2Cl with a lower highest occupied molecular orbital energy level and enhanced crystallinity than those of PBT1-C due to the high electronegativity and big atomic radius of chloride atom. When PBT1-C-2Cl is blended with the non-fullerene acceptor IT-4F, a high power conversion efficiency (PCE) of 12.7%, an open-circuit voltage (V oc) of 0.85 V and an impressive fill factor (FF) of 76.0% are achieved, which are all higher than those of PBT1-C:IT-4F based devices (PCE = 10.9%, V oc = 0.79 V and FF = 70.5%). The enhanced charge dissociation, efficient charge transport and reduced charge recombination account for the improved photovoltaic performance of PBT1-C-2Cl: IT-4F devices. The results indicate that inserting chlorine atoms onto π-bridges is a rational strategy for the synthesis of high-performance donor-π-acceptor-π type conjugated polymer donors. Graphical abstract fx1 Highlights • A novel polymer donor named PBT1-C-2Cl with chlorinated thiophene π-bridges was synthesized with high yield. • The incorporation of chlorine atom enables PBT1-C-2Cl of tight molecular packing and thereby the high hole mobility. • PBT1-C-2Cl-based solar cells exhibit a high efficiency of 12.7% with an impressivehigh fill factor of 76.0%. • The introduction of chlorine atoms onto thiophene π-bridge is a useful strategy to improve the photovoltaic performance of D-A type polymer donors. [ABSTRACT FROM AUTHOR]

Ternary structures are demonstrated as a promising approach to increase the efficiency and light harvesting of solar cells. A high power conversion efficiency of 10.2% is achieved for ternary organic solar cells with two efficient polymer donors. The improved performance is attributed to the synergistic effects of enhanced light absorption and charge transport, efficient energy transfer, improved charge generation and morphology. [ABSTRACT FROM AUTHOR]

A twisted bay‐substituted tetraphenyl functionalized perylenediimide monomer (TP‐PDI) is synthesized. A high power conversion efficiency of 4.1% is achieved for organic solar cells incorporated a combination of TP‐PDI electron acceptor and PTB7‐Th electron donor, indicating that chemical modification of PDI monomers is a useful way of designing high‐performance non‐fullerene electron acceptors. [ABSTRACT FROM AUTHOR]

Indacenodithiophene (IDT) has been widely used as the central core to design high‐performance acceptor‐donor‐acceptor (A‐D‐A)‐type non‐fullerene acceptors (NFAs). NFAs based on five‐, six‐, seven‐, and nine‐membered IDT have been successfully prepared. However, less research attention has been paid to the eight‐membered IDT derivative. In this study, a novel asymmetric TTPTTT building block as an eight‐membered IDT unit are designed and synthesized. The effect of nonfluorinated, monofluorinated, and difluorinated end‐capping groups on the photovoltaic performance of TTPTTT‐based NFAs are specifically investigated. By blending with the polymer donor PBT1‐C, organic solar cells (OSCs) based on TTPTTT‐IC, TTPTTT‐2F, and TTPTTT‐4F exhibited power conversion efficiencies (PCEs) of 7.91, 11.52, and 12.05%, respectively. Our results indicate that the asymmetric TTPTTT building block as an eight‐membered IDT derivative is a promising central core unit for designing high‐performance A‐D‐A type NFAs. A novel TTPTTT building block as an eight‐membered indacanodithiophene derivative is developed. The effect of nonfluorinated, momofluorinated, and difluorinated end‐capping group on photovoltaic performance of asymmtry TTPTTT non‐fullerene acceptors (NFAs) is investigated. As a result, organic solar cells based on TTPTTT‐4F exhibit a high efficiency of 12.05%, indicating that the asymmetric TTPTTT unit is a promising central core unit for designing efficient A‐D‐A type NFAs. [ABSTRACT FROM AUTHOR]

Semitransparent organic solar cells (STOSCs) are ideal candidates for building‐integrated photovoltaics. Power conversion efficiency (PCE) is one of the most important parameters of STOSCs, which is typically limited by the intrinsic narrow absorption of thin active layer. Ternary structure is demonstrated as an efficient approach to broaden the light absorption and manipulate the morphology, thus leading to improved PCEs by introducing a third component into the binary system. However, STOSCs based on ternary systems are rarely studied. In this contribution, semitransparent ternary solar cells are fabricated using a wide‐bandgap (Eg = 2.10 eV) polymer donor, PBT1‐S, as the third component. It is found that the addition of a small amount of PBT1‐S to PTB7‐Th:PC71BM blend has a negligible influence on its average visible transmittance (AVT) and color perception. A PCE of 9.2% is achieved for the champion ternary device with 20% AVT, which is one of the highest values for STOSCs. The results indicate that ternary structure is a promising approach for the fabrication of high‐performance STOSCs. Semitransparent organic solar cells (STOSCs) based on ternary structure are rarely studied. Here, a high efficiency of 9.2% is achieved for the champion semitransparent ternary device with 20% average visible transmittance, which is among the highest power conversion efficiencies reported for STOSCs so far. This indicates that the ternary structure is a promising strategy to fabricate high‐performance STOSCs. [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]