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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]

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]

In the development of high‐performance organic solar cells (OSCs), the self‐organization of organic semiconductors plays a crucial role. This study focuses on the precisely manipulation of molecular assemble via tuning alkyl side‐chain topology in a series of low‐cost nonfused‐ring electron acceptors (NFREAs). Among the three NFREAs investigated, DPA‐4, which possesses an asymmetric alkyl side‐chain length, exhibits a tight packing in the crystal and high crystallinity in the film, contributing to improved electron mobility and favorable film morphology for DPA‐4. As a result, the OSC device based on DPA‐4 achieves an excellent power conversion efficiency of 16.67 %, ranking among the highest efficiencies for NFREA‐based OSCs. [ABSTRACT FROM AUTHOR]

In the development of high‐performance organic solar cells (OSCs), the self‐organization of organic semiconductors plays a crucial role. This study focuses on the precisely manipulation of molecular assemble via tuning alkyl side‐chain topology in a series of low‐cost nonfused‐ring electron acceptors (NFREAs). Among the three NFREAs investigated, DPA‐4, which possesses an asymmetric alkyl side‐chain length, exhibits a tight packing in the crystal and high crystallinity in the film, contributing to improved electron mobility and favorable film morphology for DPA‐4. As a result, the OSC device based on DPA‐4 achieves an excellent power conversion efficiency of 16.67 %, ranking among the highest efficiencies for NFREA‐based OSCs. [ABSTRACT FROM AUTHOR]

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]

Developing an artificial visual sensory system requires optoelectronic materials and devices that can mimic the behavior of biological synapses. Organic/polymeric semiconductors have emerged as promising candidates for optoelectronic synapses due to their tunable optoelectronic properties, mechanic flexibility, and biological compatibility. In this review, we discuss the recent progress in organic optoelectronic synaptic materials and devices, including their design principles, working mechanisms, and applications. We also highlight the challenges and opportunities in this field and provide insights into potential applications of these materials and devices in next‐generation artificial visual systems. By leveraging the advances in organic optoelectronic materials and devices, we can envision its future development in artificial intelligence. [ABSTRACT FROM AUTHOR]

Developing an artificial visual sensory system requires optoelectronic materials and devices that can mimic the behavior of biological synapses. Organic/polymeric semiconductors have emerged as promising candidates for optoelectronic synapses due to their tunable optoelectronic properties, mechanic flexibility, and biological compatibility. In this review, we discuss the recent progress in organic optoelectronic synaptic materials and devices, including their design principles, working mechanisms, and applications. We also highlight the challenges and opportunities in this field and provide insights into potential applications of these materials and devices in next‐generation artificial visual systems. By leveraging the advances in organic optoelectronic materials and devices, we can envision its future development in artificial intelligence. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) have attracted extensive attention from both academia and industry in recent years due to their remarkable improvement in power conversion efficiency (PCE). However, the Golden Triangle (the balance of efficiency‐stability‐cost) required for large‐scale industrialization of OSCs still remains a great challenge. Here, a new nonfused‐ring electron acceptor (NFREA) BF and its polymerized counterpart PBF were designed and synthesized, and their photovoltaic performance, storage stability and material cost were systematically investigated. When blended with a widely‐used polymer donor PBDB‐T, the PBF‐based all‐polymer solar cell (all‐PSC) displayed a record high PCE of 12.61% for polymerized NFREAs (PNFREAs) with an excellent stability (95.2% of initial PCE after 800 h storage), superior to the BF counterpart. Impressively, PBF‐based all‐PSC possesses the highest industrial figure‐of‐merit (i‐FOM) value of 0.309 based on an efficiency‐stability‐cost evaluation, in comparison to several representative OSC systems (such as PM6:Y6 and PBDB‐T:PZ1). This work provides an insight into the balance of efficiency, stability, and cost, and also indicates that the PNFREAs are promising materials toward the commercial application of OSCs. [ABSTRACT FROM AUTHOR]

Novel passive devices such as all-optical diodes and all-optical logic gates require materials with appropriate both saturable and reverse saturable absorption properties. In this work, a series of GeSb4Te7 films were prepared by radio frequency magnetron sputtering and annealed at different temperatures to induce phase changes. Open-aperture Z-Scan experiments revealed that GeSb4Te7 films featured a large nonlinear absorption coefficient that varied with the extent of phase change induced by the annealing temperature. To understand the underlying reason, a three-level model was developed to explain the competition between ground-state absorption and excited-state absorption during the process. The large nonlinear absorption coefficient of GeSb4Te7 films ( β eff = - 20368.90 cm/GW) shows that ternary material demonstrates outstanding nonlinear optical absorption capability. Impressively, the annealing treatment induced microstructural changes in the GeSb4Te7 films that caused a transition from reverse saturable absorption to saturable absorption, offering great potential for innovative passive nonlinear optical devices. [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]

The power conversion efficiencies (PCEs) of all‐polymer solar cells (all‐PSCs) have already exceeded 17%. However, the limited absorption range of an all‐polymer system results in significantly reduced short‐circuit current density (Jsc), which eventually influences the PCE improvement. To broaden the light absorption of polymer acceptors, herein, benzotriazole is introduced in the core unit of small molecule acceptors and thus two narrow‐bandgap polymer acceptors named PTz‐BO and PTz‐C11 featuring the same molecular backbone and different side‐chain length are synthesized. Compared with PTz‐C11, the PTz‐BO based‐all PSCs deliver a slightly reduced Jsc, a large open‐circuit voltage (Voc) and a low voltage loss below 0.50 V. Moreover, ternary all‐PSCs are constructed by introducing PTz‐C11 as a guest component. Benefiting from the reduced recombination, improved exciton generation and dissociation, and balanced charge transport, a high efficiency of 16.58% is obtained for the ternary all‐PSCs, with a high Jsc over 25 mA cm−2 without sacrificing the Voc. Such result represents the highest efficiency reported for benzotriazole‐based all‐PSCs in the literature thus far. This work demonstrates the great potential of benzotriazole for the synthesis of efficient narrow‐bandgap polymer acceptors. [ABSTRACT FROM AUTHOR]

The development of organic solar cells (OSCs) with thick active layers is of crucial importance for the roll-to-roll printing of large-area solar panels. Unfortunately, increasing the active layer thickness usually results in a significant reduction in efficiency. Herein, we fabricated efficient thick-film OSCs with an active layer consisting of one polymer donor and two non-fullerene acceptors. The two acceptors were found to possess enlarged exciton diffusion length in the mixed phase, which is beneficial to exciton generation and dissociation. Additionally, layer by layer approach was employed to optimize the vertical phase separation. Benefiting from the synergetic effects of enlarged exciton diffusion length and graded vertical phase separation, an efficiency of 17.31% (certified value of 16.9%) is obtained for the 300 nm-thick OSC, with a short-circuit current density of 28.36 mA cm−2, and a high fill factor of 73.0%. Moreover, the device with an active layer thickness of 500 nm also shows an efficiency of 15.21%. This work provides valuable insights into the fabrication of OSCs with thick active layers. Exciton diffusion length and graded vertical phase separation of the active layer play a critical role in the realization of high-performance thick-film organic solar cells (OSCs). Here, authors demonstrated OSCs with an efficiency of 17.31%, with an active layer thickness of around 300 nm. [ABSTRACT FROM AUTHOR]

The solvent additive strategy has been widely utilized to boost the power conversion efficiency (PCE) of organic solar cells (OSCs). However, the residual solvent additive in the active layer tends to induce a gradual morphology degradation and further influences the long-term stability of OSCs. Here, a solid additive, 1,4-diiodobenzene (DIB), was introduced to fabricate efficient OSCs. We found that the treatment of DIB can lead to optimized morphology to form a bicontinuous network with intensified intermolecular packing in the donor and acceptor phases. Notably, DIB can be easily removed from the active layer via a simple alcohol washing process and no further post-thermal annealing is needed, which is desirable for large-scale manufacturing of OSCs. As a result, high efficiencies of 17.47% for PM6:Y6 and 18.13% (certified as 17.7%) for PM6:BTP-eC9 binary OSCs are achieved, which are among the highest efficiencies reported for binary OSCs thus far. Moreover, OSCs fabricated with DIB also exhibit superior stability compared with the as-cast and traditional solvent additive processed devices. Additionally, DIB was successfully applied in different active layers, manifesting its general applicability. This work provides a feasible approach to enhance both the efficiency and stability of OSCs. [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]

The development of semitransparent organic solar cells (ST‐OSCs) represents a significant step toward the commercialization of OSCs. However, the trade‐off between power conversion efficiency (PCE) and average visible transmittance (AVT) restricts further improvements of ST‐OSCs. Herein, it is demonstrated that a fibril network strategy can enable ST‐OSCs with a high PCE and AVT simultaneously. A wide‐bandgap polymer PBT1‐C‐2Cl that can self‐assemble into a fibril nanostructure is used as the donor and a near‐infrared small molecule Y6 is adopted as the acceptor. It is found that a tiny amount of PBT1‐C‐2Cl in the blend can form a high speed pathway for hole transport due to the well distributed fibril nanostructure, which increases the transmittance in the visible region. Meanwhile, the acceptor Y6 guarantees sufficient light absorption. Using this strategy, the optimized ST‐OSCs yield a high PCE of 9.1% with an AVT of over 40% and significant light utilization efficiency of 3.65% at donor/acceptor ratio of 0.25:1. This work demonstrates a simple and effective approach to realizing high PCE and AVT of ST‐OSCs simultaneously. [ABSTRACT FROM AUTHOR]

Benzo[1,2-b:4,5-b′]dithiophene (BDT) has been widely used to construct donor-acceptor (D-A) copolymers in organic solar cells (OSCs). However, benzo[1,2-b:4,5-b′]difuran (BDF), an analogue of BDT, has received less attention than BDT. The photovoltaic performance of BDF copolymers has lagged behind that of BDT copolymers. Here, we designed and synthesized two BDF copolymers, PBF1-C and PBF1-C-2Cl. PBF1-C-2Cl, which is composed of BDF and benzo[1,2-c:4,5-c′]dithiophene-4,8-dione connected by a chlorinated thiophene π-bridge, displays a low-lying highest occupied molecular orbital energy level, which helps in yielding a high open-circuit voltage (Voc) in OSCs. As a result, when blended with Y6, PBF1-C-2Cl-based devices showed a high Voc of 0.83 V and a power conversion efficiency (PCE) of 13.10%. To the best of our knowledge, the PCE of 13.10% is among the highest efficiency values for OSCs based on BDF copolymers. [ABSTRACT FROM AUTHOR]

This article discusses the challenge of industrializing organic solar cells and the need to balance efficiency, stability, and cost. The authors present a polymer acceptor called PBF, which was created using a polymerized nonfused-ring electron acceptor strategy. This polymer acceptor achieved a high efficiency of 12.61%, excellent stability, and low cost, making it a promising option for industrial applications. The authors compare the performance of PBF to other reputable systems and highlight its superior figure-of-merit. [Extracted from the article]

A bicontinuous network formed spontaneously upon film preparation is highly desirable for bulk-heterojunction (BHJ) organic solar cells (OSCs). Many donor-acceptor (D-A) type conjugated polymers can self-assemble into polymer fibrils in the solid state and such fibril-assembly can construct the morphological framework by forming a network structure, inducing the formation of ideal BHJ morphology. Our recent works have revealed that the fibril network strategy (FNS) can control the blend morphology in fullerene, non-fullerene and ternary OSCs. It has been shown that the formation of fibril network can optimize phase separation scale and ensure efficient exciton dissociation and charge carriers transport, thus leading to impressive power conversion efficiencies (PCEs) and high fill factor (FF) values. We believe that FNS will provide a promising approach for the optimization of active layer morphology and the improvement of photovoltaic performance, and further promote the commercialization of OSCs. [ABSTRACT FROM AUTHOR]

A novel strategy involving judiciously fusing one thiophene/thieno[3,2-b]thiophene on only one side of an indacenodithiophene (IDT) unit to extend IDT backbone conjugation was developed, and three A–D–A type non-fullerene small molecules (TPT-2F, TPTT-2F, and TPTTT-2F) were designed and synthesized to investigate the influence of the extent of IDT core conjugation on their photovoltaic properties. Extending the IDT core conjugation could broaden absorption, upshift the lowest unoccupied molecular orbital (LUMO) energy level, enhance electron mobility, and increase intermolecular π–π stacking. When these three non-fullerene acceptors were applied in organic solar cells (OSCs), simultaneous enhancement of the open-circuit voltage (Voc), short-circuit current (Jsc), and fill factor (FF) was obtained, with the degree of enhancement following the order TPT-2F ＜ TPTT-2F ＜ TPTTT-2F. As a result, the TPTTT-2F based OSCs yielded a high PCE of 12.03%. To the best of our knowledge, the PCE of 12.03% is among the highest values for asymmetric non-fullerene acceptor based OSCs so far. These results demonstrate that extending the conjugation of the IDT core is an effective approach to design highly efficient asymmetric non-fullerene acceptors. [ABSTRACT FROM AUTHOR]

In this work, we demonstrated the synthesis and characterization of two novel donor–acceptor type conjugated polymers, IDT-T1 and IDTT-T1, which consist of indacenodithiophene (IDT) and indacenodithieno[3,2-b]thiophene (IDTT) donor and 1,3-bis(5-bromothiophen-2-yl)-5,7-bis(2-ethylhexyl)-4H,8H-benzo[1,2-c:4,5-c]dithiophene-4,8-dione (T1) acceptor building blocks. The resulting copolymers exhibited a wide bandgap of about 1.90 eV with a comparatively low-lying highest occupied molecular orbital (HOMO) energy level. However, IDTT-T1 with an extended fused-ring unit was found to have better coplanarity and higher carrier mobility (0.11 cm2 V−1 s−1). As a consequence, organic solar cells employing IDTT-T1 as the donor material afforded a power conversion efficiency (PCE) of 6.58%, while IDT-T1-based devices yielded a relatively lower PCE of 6.26%. [ABSTRACT FROM AUTHOR]

A new 3D-structured acceptor TP3, in which three perylene diimide (PDI) units are connected together by a triptycene (TPC) core, is synthesized and characterized. Organic solar cells (OSCs) fabricated with a PTB7-Th:TP3 blend film as the active layer have been investigated and the best power conversion efficiency (PCE) of 3.16% is achieved by adding 0.5% DIO. Our studies suggest that the introduction of the TPC core could suppress the strong self-aggregation tendency of the PDI chromophores. [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]