Zheng Tang

Suppressing non‐radiative energy loss (Δ E ₃ ) by enhancing the photoluminescence quantum yield (PLQY) of active‐layer materials, particularly the acceptor component, is important for achieving high‐performance organic solar cells (OSCs). A key challenge is how to design acceptor materials that attain high PLQY while preserving favorable crystallinity and aggregation behavior, as these properties are often mutually conflicting. Here, we address this challenge by developing a series of dimeric acceptors linked via benzene, naphthalene, and anthracene bridges (named Ph‐dimer, Naph‐dimer, and Ant‐dimer). Although the conjugation length and intrinsic emission of these cores increase from benzene to anthracene, the photovoltaic performance of the resulting dimeric acceptors shows no linear correlation with this trend. Among them, the Naph‐dimer optimally balances crystallinity and PLQY, with enhanced molecular packing and reduced disorder, suppressing energy loss ( E _loss ) and facilitating charge extraction. Consequently, the PM6:Naph‐dimer OSC exhibits a power conversion efficiency (PCE) of 18.90%, an open‐circuit voltage ( V _oc ) of 0.974 V and a low Δ E ₃ of 0.192 eV, outperforming PM6:Ph‐dimer and PM6:Ant‐dimer counterparts. Moreover, incorporating Naph‐dimer into a PM6:L8‐BO host yields a PCE of 21.02%. These findings indicate that precise bridge modulation is an effective strategy for harmonizing high PLQY with crystalline order in OSCs.

This work establishes a core-appended steric engineering to address the critical challenge of non-radiative recombination energy loss in organic solar cells through precisely regulating local conformation and intermolecular interactions.

Suppressing non‐radiative energy loss (Δ E ₃ ) by enhancing the photoluminescence quantum yield (PLQY) of active‐layer materials, particularly the acceptor component, is important for achieving high‐performance organic solar cells (OSCs). A key challenge is how to design acceptor materials that attain high PLQY while preserving favorable crystallinity and aggregation behavior, as these properties are often mutually conflicting. Here, we address this challenge by developing a series of dimeric acceptors linked via benzene, naphthalene, and anthracene bridges (named Ph‐dimer, Naph‐dimer, and Ant‐dimer). Although the conjugation length and intrinsic emission of these cores increase from benzene to anthracene, the photovoltaic performance of the resulting dimeric acceptors shows no linear correlation with this trend. Among them, the Naph‐dimer optimally balances crystallinity and PLQY, with enhanced molecular packing and reduced disorder, suppressing energy loss ( E _loss ) and facilitating charge extraction. Consequently, the PM6:Naph‐dimer OSC exhibits a power conversion efficiency (PCE) of 18.90%, an open‐circuit voltage ( V _oc ) of 0.974 V and a low Δ E ₃ of 0.192 eV, outperforming PM6:Ph‐dimer and PM6:Ant‐dimer counterparts. Moreover, incorporating Naph‐dimer into a PM6:L8‐BO host yields a PCE of 21.02%. These findings indicate that precise bridge modulation is an effective strategy for harmonizing high PLQY with crystalline order in OSCs.

In organic solar cells (OSCs), the morphology of charge transport layers (CTLs) is as critical as that of the active layer, directly governing charge transport and collection efficiency as well as overall device performance. However, current CTL design predominantly focuses on molecular structure engineering, while systematic morphological control of CTLs remains largely underexplored. Herein, we report a seed‐initiated epitaxial growth strategy to construct well‐ordered fibrillar electron transport layers (ETLs) with tunable fiber lengths and narrow dispersity. This nanofiber‐textured ETL provides dedicated pathways for efficient electron transport and extraction, while its enlarged contact area strengthens interlayer adhesion, improving both interfacial charge transport and mechanical integrity. Using this ETL, power conversion efficiencies of 20.6% in rigid binary OSCs and 19.1% in flexible ones are achieved. The nanofibrillar ETL also exhibits broad active layer compatibility, excellent thickness tolerance, and outstanding mechanical stability. This work provides new insights into ETL morphological engineering as a strategy to overcome interfacial bottlenecks, unlocking significant efficiency gains in OSCs.

In organic solar cells (OSCs), the morphology of charge transport layers (CTLs) is as critical as that of the active layer, directly governing charge transport and collection efficiency as well as overall device performance. However, current CTL design predominantly focuses on molecular structure engineering, while systematic morphological control of CTLs remains largely underexplored. Herein, we report a seed‐initiated epitaxial growth strategy to construct well‐ordered fibrillar electron transport layers (ETLs) with tunable fiber lengths and narrow dispersity. This nanofiber‐textured ETL provides dedicated pathways for efficient electron transport and extraction, while its enlarged contact area strengthens interlayer adhesion, improving both interfacial charge transport and mechanical integrity. Using this ETL, power conversion efficiencies of 20.6% in rigid binary OSCs and 19.1% in flexible ones are achieved. The nanofibrillar ETL also exhibits broad active layer compatibility, excellent thickness tolerance, and outstanding mechanical stability. This work provides new insights into ETL morphological engineering as a strategy to overcome interfacial bottlenecks, unlocking significant efficiency gains in OSCs.

The realization of high–efficiency as–cast organic solar cells (OSCs) represents a key step toward simplified processing and scalable fabrication for commercialization. However, achieving high–performance as–cast devices remains challenging because it demands delicate balance between donor–acceptor self–aggregation and miscibility. Herein, we fabricate as–cast OSCs through Flory–Huggins parameter (χ) engineering that precisely regulates donor–acceptor miscibility during solution casting. The chloroform–carbon disulfide (CF:CS ₂ ) mixed solvent, with tailored solubility and evaporation kinetics, dynamically modulates χ to form an optimized bulk heterojunction featuring desirable phase separation and a well–balanced fibrillar network. This design affords efficient exciton dissociation, facilitated charge transport, and suppressed recombination in the blend. Consequently, as–cast D18:L8–BO device processed with the CF:CS ₂ solvent system attained a PCE of 20.11% (certified as 19.69%) alongside enhanced photostability, representing the highest efficiency reported for as–cast devices. Besides, high PCEs of 18.89% and 15.12% are achieved in thick–film (300 nm) and large–area (20.17 cm ² ) as–cast devices. Moreover, a quantitative correlation between PCE and the interaction parameter χ is established, providing a quantitative guide for narrowing the miscibility window and identifying the optimal composition. These findings validate the efficacy of χ–parameter–mediated miscibility engineering in regulating blend phase behavior and provide a framework for advancing efficient as–cast OSCs.

Achieving both high power conversion efficiency (PCE) and long‐term operational stability remains a formidable challenge for organic solar cells (OSCs). Dimeric small‐molecule acceptors (DSMAs), constructed by linking small‐molecule acceptor (SMA) subunits, have recently emerged as promising candidates. However, their conventional synthesis via Stille coupling necessitates multistep reactions, rendering large‐scale, low‐cost preparation impractical. Herein, we report a streamlined direct dimerization strategy that efficiently constructs core‐linked DSMAs through the condensation of bromoacetyl groups with diamine subunits, obviating the need for expensive palladium catalysts and toxic organotin reagents. By systematically varying the linking units, we synthesized a series of DSMAs with precisely tunable optical and electronic properties, demonstrating the generality of the approach. Such a direct dimerization approach effectively resolves the long‐standing trade‐off between cost‐effective synthesis and high photovoltaic performance. Consequently, the best‐performing device delivers a record‐high PCE of 20.15%, while maintaining outstanding photostability. Collectively, this work provides a versatile blueprint for the cost‐effective synthesis of stable, high‐performance DSMAs, effectively bridging the gap between molecular design and practical OSC scalability.

Achieving both high power conversion efficiency (PCE) and long‐term operational stability remains a formidable challenge for organic solar cells (OSCs). Dimeric small‐molecule acceptors (DSMAs), constructed by linking small‐molecule acceptor (SMA) subunits, have recently emerged as promising candidates. However, their conventional synthesis via Stille coupling necessitates multistep reactions, rendering large‐scale, low‐cost preparation impractical. Herein, we report a streamlined direct dimerization strategy that efficiently constructs core‐linked DSMAs through the condensation of bromoacetyl groups with diamine subunits, obviating the need for expensive palladium catalysts and toxic organotin reagents. By systematically varying the linking units, we synthesized a series of DSMAs with precisely tunable optical and electronic properties, demonstrating the generality of the approach. Such a direct dimerization approach effectively resolves the long‐standing trade‐off between cost‐effective synthesis and high photovoltaic performance. Consequently, the best‐performing device delivers a record‐high PCE of 20.15%, while maintaining outstanding photostability. Collectively, this work provides a versatile blueprint for the cost‐effective synthesis of stable, high‐performance DSMAs, effectively bridging the gap between molecular design and practical OSC scalability.

To address the critical challenge of the scarcity of low‐cost wide‐bandgap polymer donor materials, we have developed a novel ester‐substituted benzotrithiophene acceptor unit. The incorporation of an ester group into the benzotrithiophene structure induces a fundamental transformation, shifting it from an electron‐donating entity to a weakly electron‐withdrawing one. Leveraging this innovation, we synthesized a new low‐cost wide‐bandgap polymer donor material, namely BLZ‐20 , by using the ester‐functionalized benzotrithiophene as the acceptor unit, benzodithiophene (BDT) as the donor unit, and 3‐alkylthiophene as the π ‐bridge. BLZ‐20 exhibits excellent solution‐processability and unique temperature‐dependent aggregation properties. Building on these advantageous characteristics, the BLZ‐20 :L8‐BO blend film exhibits a well‐defined nanofiber network structure that not only promotes efficient exciton dissociation and charge transport but also effectively reduces nonradiative losses. The BLZ‐20 :L8‐BO‐based binary organic solar cell (OSC) has achieved a remarkable power conversion efficiency (PCE) of 20.13%, setting a new industry‐wide benchmark for OSCs. Furthermore, the BLZ‐20 :L8‐BO:BTP‐eC9‐based ternary OSC has attained an even more impressive PCE of 20.55%, ranking among the highest‐performing OSCs ever reported. Our research findings unequivocally demonstrate that the wide‐bandgap polymer BLZ‐20 , derived from benzotrithiophene, is a cost‐effective and high‐performance donor material. It offers significant potential for advancing the practical application of OSCs.