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Minimizing energy loss is crucial for breaking through the efficiency bottleneck of organic solar cells (OSCs). The main mechanism of energy loss can be attributed to non‐radiative recombination energy loss (ΔEnr) that occurs due to exciton–vibration coupling. To tackle this challenge, tuning intramolecular noncovalent interactions is strategically utilized to tailor novel fused ring electron acceptors (FREAs). Upon comprehensive analysis of both theoretical and experimental results, this approach can effectively enhance molecular rigidity, suppress structural relaxation, reduce exciton reorganization energy, and weakens exciton–vibration coupling strength. Consequently, the binary OSC device based on Y‐SeSe, which features dual strong intramolecular Se ⋅ ⋅ ⋅ O noncovalent interactions, achieves an outstanding power conversion efficiency (PCE) of 19.49 %, accompanied by an extremely small ΔEnr of 0.184 eV, much lower than those of Y‐SS and Y‐SSe based devices with weaker intramolecular noncovalent interactions. These achievements not only set an efficiency record for selenium‐containing OSCs, but also mark the lowest reported ΔEnr value among high‐performance binary devices. Furthermore, the ternary blend device showcases a remarkable PCE of 20.51 %, one of the highest PCEs for single‐junction OSCs. This work demonstrates the effectiveness of intramolecular noncovalent interactions in suppressing exciton–vibration coupling, thereby achieving low‐energy‐loss and high‐efficiency 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]

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 large energy loss (Eloss) is one of the main obstacles to further improve the photovoltaic performance of organic solar cells (OSCs), which is closely related to the charge transfer (CT) state. Herein, ternary donor alloy strategy is used to precisely tune the energy of CT state (ECT) and thus the Eloss for boosting the efficiency of OSCs. The elevated ECT in the ternary OSCs reduce the energy loss for charge generation (ΔECT), and promote the hybridization between localized excitation state and CT state to reduce the nonradiative energy loss (ΔEnonrad). Together with the optimal morphology, the ternary OSCs afford an impressive power conversion efficiency of 19.22% with a significantly improved open‐circuit voltage (Voc) of 0.910 V without sacrificing short‐cicuit density (Jsc) and fill factor (FF) in comparison to the binary ones. This contribution reveals that precisely tuning the ECT via donor alloy strategy is an efficient way to minimize Eloss and improve the photovoltaic performance of OSCs. [ABSTRACT FROM AUTHOR]

The innovation of high‐performance fused‐ring electron acceptors (FREAs) has carried the field of organic solar cells (OSCs) toward a new stage of development. However, due to high synthetic complexity and production costs, FREAs may not be the most promising candidates for future commercialization applications. To address these disadvantages of FREAs, a series of low‐cost acceptors, named as noncovalently FREAs (NFREAs), is successfully constructed by employing the strategy of noncovalently conformational locks. Herein, a novel NFREA (BDTO‐4F) based on 3,7‐dialkyloxybenzo[1,2‐b:4,5‐b′]dithiophene is synthesized and fully characterized. Benefiting from the complementary absorption of the donor and acceptor, balanced charge transport, and favorable film morphology, J52:BDTO‐4F based OSCs afford a satisfied power conversion efficiency of 12.09%, much higher than PBDB‐T:BDTO‐4F‐based devices (8.30%). It is worth mentioning that BDTO‐4F possesses a higher figure‐of‐merit value of 55.65 in comparison with several representative FREAs based on a cost‐efficiency evaluation. This work demonstrates the potential of the novel benzo[1,2‐b:4,5‐b″]dithiophene derivative for constructing low‐cost and high‐performance NFREAs, providing a valuable insight on the materials design. [ABSTRACT FROM AUTHOR]

The rapid advance of fused‐ring electron acceptors (FREAs) has greatly promoted the leap‐forward development of organic solar cells (OSCs). However, the synthetic complexity of FREAs may be detrimental for future commercial applications. Recently, nonfused‐ring electron acceptors (NREAs) have been developed to be a promising candidate to maintain a rational balance between cost and performance, of which the cores are composed of simple fused rings (NREAs‐I) or nonfused rings (NREAs‐II). Moreover, "noncovalently conformational locks", are used as an effective strategy to enhance the rigidity and planarity of NREAs and improve device performance. Herein, a novel series of NREAs‐II (PhO4T‐1, PhO4T‐2, and PhO4T‐3) is constructed as a valuable platform for exploring the impact of the end group engineering on optoelectronic properties, intermolecular packing behaviors, and device performance. As a result, a high power conversion efficiency of 13.76% is achieved for PhO4T‐3 based OSCs, which is much higher than those of the PhO4T‐1 and PhO4T‐2‐based devices. Compared with several representative FREAs, PhO4T‐3 possesses the highest figure‐of‐merit value of 133.45 based on a cost‐efficiency evaluation. This work demonstrates that the simple‐structured NREAs‐II are promising candidates for low‐cost and high‐performance OSCs. [ABSTRACT FROM AUTHOR]

Triplet excitons have both longer lifetimes and diffusion lengths than singlet excitons due to the nature of triplet excitons, which is expected to increase the photocurrent and further improve the performance of organic solar cells (OSCs). However, the working mechanism of triplet excitons in OSCs is not clearly clarified. Therefore, it is urgent to develop new triplet acceptors for in‐depth understanding. Herein, a series of acceptors (BTn‐4Cl) are synthesized by fine‐tuning of the side‐chain branch positions. The generation of triplet excitons of BTn‐4Cl is confirmed by the time‐resolved photoluminescence (TRPL) spectra, magnetophotocurrent (MPC) experiment, and electron paramagnetic resonance (EPR) spectra. The effects of side‐chain engineering on the optoelectronic properties, packing behaviors, energy losses, charge transport properties, spin lifetimes of triplet polarons, and blend film morphologies are systematically studied. These results show that D18:BT3‐4Cl‐based OSCs possess the best power conversion efficiency (PCE) of 17.31% due to lower energy losses, less recombination losses, more balanced charge carrier mobilities, longer spin–lattice (T1) relaxation time, and more favorable morphology. This work enhances the understanding of the structure–property relationship for high‐performance triplet acceptors. [ABSTRACT FROM AUTHOR]

Side‐chain engineering is an effective strategy to regulate the solubility and packing behavior of organic materials. Recently, a unique strategy, so‐called terminal side‐chain (T‐SC) engineering, has attracted much attention in the field of organic solar cells (OSCs), but there is a lack of deep understanding of the mechanism. Herein, a new noncovalently fused‐ring electron acceptor (NFREA) containing two T‐SCs (NoCA‐5) was designed and synthesized. Introduction of T‐SCs can enhance molecular rigidity and intermolecular π–π stacking, which is confirmed by the smaller Stokes shift value, lower reorganization free energy, and shorter π–π stacking distance in comparison to NoCA‐1. Hence, the NoCA‐5‐based device exhibits a record power conversion efficiency (PCE) of 14.82 % in labs and a certified PCE of 14.5 %, resulting from a high electron mobility, a short charge‐extraction time, a small Urbach energy (Eu), and a favorable phase separation. [ABSTRACT FROM AUTHOR]

Noncovalently fused‐ring electron acceptors (NFREAs) have attracted much attention in recent years owing to their advantages of simple synthetic routes, high yields and low costs. However, the efficiencies of NFREAs based organic solar cells (OSCs) are still far behind those of fused‐ring electron acceptors (FREAs). Herein, a series of NFREAs with S⋅⋅⋅O noncovalent intramolecular interactions were designed and synthesized with a two‐step synthetic route. Upon introducing π‐extended end‐groups into the backbones, the electronic properties, charge transport, film morphology, and energy loss were precisely tuned by fine‐tuning the degree of multi‐fluorination. As a result, a record PCE of 14.53 % in labs and a certified PCE of 13.8 % for NFREAs based devices were obtained. This contribution demonstrated that combining the strategies of noncovalent conformational locks and π‐extended end‐group engineering is a simple and effective way to explore high‐performance NFREAs. [ABSTRACT FROM AUTHOR]

Isomeric effects play a crucial role in regulating electronic properties, molecular packing, and device performance of organic semiconductors. Herein, a series of unfused‐ring electron acceptor (UREA) regioisomers (NOF‐1, NOF‐2, and NOF‐3), which are constructed using 2,6‐α‐, 1,5‐β‐, and 3,7‐β‐type naphthalene cores, are successfully synthesized and characterized. The regioisomeric effects on geometries, photophysics, electrical properties, molecular packing behaviors, charge transport properties, blend film morphologies, and photovoltaic performance are systematically studied. As a result, the PBDB‐T:NOF‐3‐based device delivers a power conversion efficiency (PCE) of 11.58% due to its more balanced charge mobility, efficient exciton dissociation, less charge recombination, and favorable film morphology. These findings encourage further attention to the regioisomeric effects to design high‐performance UREAs. [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]