Morphology Of Active Layer Research Articles

The Pseudo-Bilayer Bulk Heterojunction Active Layer of Polymer Solar Cells in Green Solvent with 18.48% Efficiency

Planar heterojunction (PHJ) is employed to obtain proper vertical phase separation for highly efficient polymer solar cells (PSCs). However, it heavily relies on the choice of orthogonal solvent in the production process. Here, we fabricated a pseudo-bilayer bulk heterojunction (PBHJ) PSC with cross-distribution in the vertical direction by preparing two layers of PM6 and BTP-eC9 blends in an o-XY solution with different dilution ratios to study the morphological evolution of PBHJ film. We found that the PBHJ film exhibits more uniform and suitable continuous interpenetrating network morphology and proper phase separation in the vertical direction for the formation of p-i-n structure. This provides an effective channel for exciton dissociation and charge transport, which is confirmed by both exciton generation simulations and charge dynamics measurements. The PBHJ devices can effectively inhibit trap recombination and accelerate charge separation and transfer. Based on good active layer morphology and balanced charge mobility, all-green solvent-processed PSCs with champion power conversion efficiencies (PCEs) of 18.48% and 16.83% are obtained in PM6:BTP-eC9 and PTQ10:BTP-eC9 systems, respectively. This work reveals the potential mechanism of morphological evolution induced by the PBHJ structure and provides an alternative approach for developing solution processing PSCs.

Recent Advances in Polymorphism of Organic Solar Cells.

As organic solar cells (OSCs) achieve notable advancements, a significant consensus has been highlighted that the device performance is intricately linked to the active layer morphology. With conjugated molecules being widely employed, intermolecular interactions exert substantial influence over the aggregation state and morphology formation, resulting in distinct molecular packing motifs, also known as polymorphism. This phenomenon is closely associated with processing conditions and exerts a profound impact on functional properties. Consequently, understanding the mechanisms underlying polymorphism formation and establishing a definitive correlation between polymorphism and photophysical behavior is crucial for driving high-performance OSCs. In this review, a comprehensive synthesis of recent developments is provided and emphasizing its pivotal role in the field of OSC polymorphism. The thermodynamic and kinetic principles governing polymorphism formation are examined. Then, representative polymorphisms are classified in OSC materials, segmenting them into homopolymers, copolymers, and IDTT- and BTP-based small molecules. Additionally, prevalent strategies are evaluated for manipulating polymorphism. This review culminates with an analysis of the critical effects of polymorphism on OSCs, including charge carrier characteristics, photovoltaic efficiency, and long-term stability. By offering novel perspectives and practical insights, this work seeks to guide future efforts in the morphological optimization of high-efficiency OSCs.

Thickness-Dependent Electrical Simulation of Ternary Layer-by-Layer Organic Solar Cell

Recently, researchers have been interested in incorporating a third component into the active layer of organic solar cells (OSC). Introducing a third component aims to improve the efficiency of light absorption, charge separation, and transport within the solar cell. It is widely observed that varying active layer thicknesses result in different device competencies due to the behaviour of charge transportation and charge collection in such volume morphology of active layer. This paper incorporated layer-by-layer (LbL) devices based on BTR-Cl as donor and IT-2Cl as acceptor with Y6 acceptor as a third component in the active layer. These devices had been electrically characterized using organic and hybrid material nano (OghmaNano) simulation tool. A thickness ranging between 40 nm and 100 nm of each material in the active layer was evaluated in this simulation. This simulation shows the current-voltage (I-V) characteristics for ternary LbL OSC devices at various thicknesses. The short circuit current density (Jsc), open circuit voltage (Voc), and fill factor (FF) for each device's active layer thickness were also provided. At a thickness ratio of 50:60:50 nm (BTR-Cl to Y6 to IT-2Cl) and 100 mW cm-2, AM1.5 incident solar radiance, the maximum attainable efficiency, 12.1%, was found.

Dual Additive Strategy with Quasi-Planar Heterojunction Architecture Assisted in Morphology Optimization for High-Efficiency Organic Solar Cells.

Achieving high-performance and stable organic solar cells (OSCs) remains a critical challenge, primarily due to the precise optimization required for active layer morphology. Herein, this work reports a dual additive strategy using 3,5-dichlorobromobenzene (DCBB) and 1,8-diiodooctane (DIO) to optimize the morphology of both bulk-heterojunction (BHJ) and quasi-planar heterojunction (Q-PHJ) based on donor D18 and acceptor BTP-eC9. The systematic results reveal that the dual additive strategy significantly promotes phase separation while inhibiting excessive aggregation, which, in turn, improves molecular order and crystallization. As a result, BHJ and Q-PHJ OSCs processed with dual additive DIO + DCBB achieve impressive power conversion efficiencies of 17.77% and 18.60%, respectively, the highest reported values for dual additive-processed OSCs. The superior performance is attributed to improved charge transport and reduced recombination losses, as evidenced by higher short-circuit current densities (JSC) and fill factors (FF). Importantly, Q-PHJ OSCs processed with either DCBB or DIO + DCBB, in comparison to BHJ OSCs, exhibit exceptional shelf-stability, maintaining 80% of their initial power conversion efficiency after 2660 and 2193 h, respectively. These findings underscore the potential of dual additive strategies to advance the development of stable, high-efficiency OSCs suitable for large-area fabrication, marking a significant step forward in renewable energy technology.

Brominated isomerization engineering of 1-chloronaphthalene derived solid additives enables 19.68% efficiency organic solar cells

Using halogenated additive to optimize the active layer morphology has been proven effective in boosting the power conversion efficiency (PCE) of organic solar cells (OSCs). However, the halogenated isomerism of solid additives, which finely tunes blend morphology, has been understudied, with the associated mechanisms requiring further investigation. Herein, a brominated isomerization engineering using 1-chloronaphthalene (CN)-derived solid additives (2-bromo-1-chloronaphthalene/o-BrCN, 3-bromo-1-chloronaphthalene/m-BrCN, and 4-bromo-1-chloronaphthalene/p-BrCN, respectively) is firstly developed. Among these, p-BrCN, with symmetrically halogenated positions, exhibits a small dipole moment, facilitating an extraordinary non-covalent interaction with both donor and acceptor components. Consequently, the p-BrCN-treated active layer obtains better molecular crystallinity, π-π stacking, and phase separation, helping to improve the exciton dissociation and charge transport of OSCs. Ultimately, the p-BrCN-treated OSC based on PM6:L8-BO offers a higher PCE (18.18%) compared to those treated with o-BrCN (17.89%) and m-BrCN (17.39%). Remarkably, the p-BrCN-treated OSCs based on D18:L8-BO and D18:L8-BO:BTP-eC9 further improve PCEs to 19.14% and 19.68%, placing them among the highest values for binary and ternary OSCs, respectively. This work highlights that brominated isomerization engineering in CN-derived additives is a promising strategy to optimize morphology for obtaining efficient OSCs, and elucidates the underlying mechanism.

Terminal Fluorination Modulates Crystallinity and Aggregation of Fully Non‐Fused Ring Electron Acceptors for High‐Performance and Durable Near‐Infrared Organic Photodetectors

High dark current density (Jd) severely hinders further advancement of near‐infrared organic photodetectors (NIR OPDs). Herein, we tackle this grand challenge by regulating molecular crystallinity and aggregation of fully non‐fused ring electron acceptors (FNREAs). In contrast to the general trend in terminal halogenation of electron acceptors, TBT‐V‐F, featuring fluorinated terminals, notably demonstrates crystalline intensification and a higher prevalence predominance of J‐aggregate compared to its chlorinated counterpart (TBT‐V‐Cl). The amalgamation of advantages confers TBT‐V‐F‐based OPDs with more organized active layer morphology and denser molecular packing, resulting in improved charge transport, decreased energetic disorder, and reduced trap density. Consequently, the corresponding self‐powered OPDs exhibit a 40‐fold decrease in Jd, a remarkable increase in detectivity (D*sh), faster response time, and superior thermal stability compared to TBT‐V‐Cl‐based OPDs. Further interfacial optimization results in an ultra‐low Jd of 7.30´10‐12 A cm‐2 with D*sh over 1013 Jones in 320‐920 nm wavelength and a climax of 2.2´1014 Jones at 800 nm for the TBT‐V‐F‐based OPDs, representing one of the best results reported to date. This work paves a compelling material‐based strategy to suppress Jd for highly sensitive NIR OPDs, while also illustrates the viability of FNREAs in construction of stable and affordable NIR OPDs for real‐world applications.

Terminal Fluorination Modulates Crystallinity and Aggregation of Fully Non-Fused Ring Electron Acceptors for High-Performance and Durable Near-Infrared Organic Photodetectors.

High dark current density (Jd) severely hinders further advancement of near-infrared organic photodetectors (NIR OPDs). Herein, we tackle this grand challenge by regulating molecular crystallinity and aggregation of fully non-fused ring electron acceptors (FNREAs). In contrast to the general trend in terminal halogenation of electron acceptors, TBT-V-F, featuring fluorinated terminals, notably demonstrates crystalline intensification and a higher prevalence predominance of J-aggregate compared to its chlorinated counterpart (TBT-V-Cl). The amalgamation of advantages confers TBT-V-F-based OPDs with more organized active layer morphology and denser molecular packing, resulting in improved charge transport, decreased energetic disorder, and reduced trap density. Consequently, the corresponding self-powered OPDs exhibit a 40-fold decrease in Jd, a remarkable increase in detectivity (D*sh), faster response time, and superior thermal stability compared to TBT-V-Cl-based OPDs. Further interfacial optimization results in an ultra-low Jd of 7.30´10-12 A cm-2 with D*sh over 1013 Jones in 320-920 nm wavelength and a climax of 2.2´1014 Jones at 800 nm for the TBT-V-F-based OPDs, representing one of the best results reported to date. This work paves a compelling material-based strategy to suppress Jd for highly sensitive NIR OPDs, while also illustrates the viability of FNREAs in construction of stable and affordable NIR OPDs for real-world applications.

Efficient All‐Polymer Solar Cells Enabled by a Novel Medium Bandgap Guest Acceptor

Comprehensive SummaryNear‐infrared (NIR)‐absorbing polymerized small molecule acceptors (PSMAs) based on a Y‐series backbone (such as PY‐IT) have been widely developed to fabricate efficient all‐polymer solar cells (all‐PSCs). However, medium‐bandgap PSMAs are often overlooked, while they as the third component can be expected to boost power conversion efficiencies (PCEs) of all‐PSCs, mainly due to their up‐shifted lowest unoccupied molecular orbital (LUMO) energy level, complimentary absorption, and diverse intermolecular interaction compared to the NIR‐absorbing host acceptor. Herein, an IDIC‐series medium‐bandgap PSMA (P‐ITTC) is developed and introduced as the third component into D18/PY‐IT host, which can not only form complementary absorption and cascade energy level, but also finely optimize active layer morphology. Therefore, compared to the D18/PY‐IT based parental all‐PSCs, the ternary all‐PSCs based on D18/PY‐IT:P‐ITTC obtain an increased exciton dissociation, charge transport, carrier lifetime, as well as suppressed charge recombination and energy loss. As a result, the ternary all‐PSCs achieve a high PCE of 17.64% with a photovoltage of 0.96 V, both of which are among the top values in layer‐by‐layer typed all‐PSCs. This work provides a method for the design and selection of the medium‐bandgap third component to fabricate efficient all‐PSCs.

Volatile Additive Assists Binary Layer‐by‐Layer Solution Processing Organic Solar Cells to Achieve 19% Efficiency

Comprehensive SummaryLayer‐by‐layer (LbL) solution processing is an efficient method to realize high performance organic solar cells (OSCs). One of the drawbacks of the LbL‐processed active layer is the large difference in the crystallinity of the donor and acceptor, which will lead to imbalance charge transfer and result in unfavorable charge recombination. Herein, we combined a novel volatile additive 3,5‐dichloro‐2,4,6‐ trifluorobenzotrifluoride (DTBF) with the LbL method to realize high‐efficiency OSCs. DTBF interacts with the non‐fullerene acceptor BTP‐4F by non‐covalent bonding, which enhances the crystallinity and compact stacking of BTP‐4F. DTBF doped OSC has balanced and efficient electron transport properties, longer carrier lifetime, higher exciton dissociation and charge collection efficiencies, lower energetic disorder than the control OSC without any additives. Benefiting from the optimization of charge dynamics and micro‐morphology by DTBF, the binary LbL‐processed OSC achieved synergistic improvements in open‐circuit voltage, short‐circuit current density and fill factor. As a result, a champion power conversion efficiency (PCE) of 19% is realized for DTBF‐optimized OSC, which is superior to the control OSC (17.55%). This work demonstrates a promising approach to modulate active layer morphology and fabricate high performance OSCs.

Boosting the Efficiency of Perovskite/Organic Tandem Solar Cells via Enhanced Near-Infrared Absorption and Minimized Energy Losses.

The compatibility of perovskite and organic photovoltaic materials in solution processing provides a significant advantage in the fabrication of high-efficiency perovskite/organic tandem solar cells. However, additional recombination losses can occur during exciton dissociation in organic materials, leading to energy losses in the near-infrared region of tandem devices. Consequently, a ternary organic rear subcell is designed containing two narrow-bandgap non-fullerene acceptors to enhance the absorption of near-infrared light. Simultaneously, a unique diffusion-controlled growth technique is adopted to optimize the morphology of the ternary active layer, thereby improving exciton dissociation efficiency. This innovation not only broadens the absorption range of near-infrared light but also facilitates the generation and effective dissociation of excitons. Owing to these technological improvements, the power conversion efficiency (PCE) of organic solar cells increased to 19.2%. Furthermore, a wide-bandgap perovskite front subcell is integrated with a narrow-bandgap organic rear subcell to develop a perovskite/organic tandem solar cell. Owing to the reduction in near-infrared energy loss, the PCE of this tandem device significantly improved, reaching 24.5%.

Solid additive modulates acceptor crystallization to achieve 19.11% efficiency and high storage stability in organic solar cells

Ideal nanoscale phase-separated morphology is the primary condition to obtain high photovoltaic conversion efficiency (PCE) and high stability of organic solar cells (OSCs). However, the differences in solubility, miscibility and crystallinity between donors and acceptors make it difficult to achieve the optimal active layer morphology of OSCs. Herein, the volatile solid additive 3,5-dibromotoluene (DTL) with strong electronegativity and dipole moment has been developed for OSCs. DTL can interact with the acceptor, modulating its crystallization and stacking, enhancing donor/acceptor miscibility, reducing trap density, inhibiting carrier recombination, and balancing charge transport. Notably, the introduction of DTL finely tunes the energy level of the acceptor, which greatly enhances the open-circuit voltage (VOC) of the device compared to the conventional additive 1,8-diiodooctane (DIO). As a result, the DTL-treated PM6: L8-BO-based OSCs obtained a high PCE of 18.87% and enhanced stability. Furthermore, the PM6: PM1: L8-BO+ DTL-based OSCs achieved a champion PCE of 19.11%. This work deepens the working mechanism of additive strategy for regulating the morphology and improving performance, providing an effective method for achieving high-performance OSCs.

Enabling High‐Efficiency and Stable Binary Organic Solar Cells by Solid Additive‐Assisted Morphology Modulation

AbstractThe solid additive strategy represents a simple yet effective approach to achieving high‐efficiency organic solar cells (OSCs) by enhancing the morphology of the active layer. In this study, a highly volatile solid additive, 2,4,6‐trichloro‐1,3,5‐triazine (TCT), is employed to modulate the morphology. Unlike other solid additives previously reported, TCT exhibits remarkable intermolecular interactions with both polymer donor and acceptor, offering two distinct advantages. Firstly, TCT notably enhances the crystallinity and molecular order of the blend film, subtly optimizing the fiber network structure within, thereby facilitating carrier transport and significantly improving the mobility of the blend film. Secondly, TCT stabilizes the bi‐continuous fibrous morphology of the polymer donor and acceptor, mitigating the morphological evolution of the active layer and enhancing device stability. Consequently, the D18:L8‐BO:TCT device exhibits a higher power conversion efficiency of 19.50% compared to the D18:L8‐BO device (18.13%). Furthermore, after 960 h of storage, the OSC device treated with TCT retains 90% of its initial PCE, significantly outperforming the D18:L8‐BO device (73%). This study presents a promising avenue for achieving high‐performance OSCs through manipulating the active layer morphology with solid additives.

Configurational Isomerization‐Induced Orientation Switching: Non‐Fused Ring Dipodal Phosphonic Acids as Hole‐Extraction Layers for Efficient Organic Solar Cells

AbstractPhosphonic acid (PA) self‐assembled molecules have recently emerged as efficient hole‐extraction layers (HELs) for organic solar cells (OSCs). However, the structural effects of PAs on their self‐assembly behaviors on indium tin oxide (ITO) and thus photovoltaic performance remain obscure. Herein, we present a novel class of PAs, namely “non‐fused ring dipodal phosphonic acids” (NFR‐DPAs), featuring simple and malleable non‐fused ring backbones and dipodal phosphonic acid anchoring groups. The efficacy of configurational isomerism in modulating the photoelectronic properties and switching molecular orientation of PAs atop electrodes results in distinct substrate surface energy and electronic characteristics. The NFR‐DPA with linear (C2h symmetry) and brominated backbone exhibits favorable face‐on orientation and enhanced work function modification capability compared to its angular (C2v symmetry) and non‐brominated counterparts. This makes it versatile HELs in mitigating interfacial resistance for energy barrier‐free hole collection, and affording optimal active layer morphology, which results in an impressive efficiency of 19.11 % with a low voltage loss of 0.52 V for binary OSC devices and an excellent efficiency of 19.66 % for ternary OSC devices. This study presents a new dimension to design PA‐based HELs for high‐performance OSCs.

Configurational Isomerization-Induced Orientation Switching: Non-Fused Ring Dipodal Phosphonic Acids as Hole-Extraction Layers for Efficient Organic Solar Cells.

Phosphonic acid (PA) self-assembled molecules have recently emerged as efficient hole-extraction layers (HELs) for organic solar cells (OSCs). However, the structural effects of PAs on their self-assembly behaviors on indium tin oxide (ITO) and thus photovoltaic performance remain obscure. Herein, we present a novel class of PAs, namely "non-fused ring dipodal phosphonic acids" (NFR-DPAs), featuring simple and malleable non-fused ring backbones and dipodal phosphonic acid anchoring groups. The efficacy of configurational isomerism in modulating the photoelectronic properties and switching molecular orientation of PAs atop electrodes results in distinct substrate surface energy and electronic characteristics. The NFR-DPA with linear (C2h symmetry) and brominated backbone exhibits favorable face-on orientation and enhanced work function modification capability compared to its angular (C2v symmetry) and non-brominated counterparts. This makes it versatile HELs in mitigating interfacial resistance for energy barrier-free hole collection, and affording optimal active layer morphology, which results in an impressive efficiency of 19.11 % with a low voltage loss of 0.52 V for binary OSC devices and an excellent efficiency of 19.66 % for ternary OSC devices. This study presents a new dimension to design PA-based HELs for high-performance OSCs.

Dual Additive‐Assisted Layer‐by‐Layer Processing for 19.59% Efficiency Quasi‐Bulk Heterojunction Organic Solar Cells

AbstractThe ideal vertical phase separation active layer morphology is crucial for the photoelectric conversion of organic solar cells. In this work, a layer‐by‐layer sequential deposition method is used to prepare D18/L8‐BO‐based organic solar cells and a dual additives strategy is adopted to construct the ideal active layer. Additive DIM regulates the crystallization of the D18 layer, and additive DIO induces L8‐BO to diffuse into the interior of the D18 layer to form a vertical composition distribution with large donor/acceptor interpenetrated regions. The improvement of active layer induced by DIM and DIO dual additives promote exciton generation and dissociation, shorten charge transfer distance, and improve carrier dynamics. With improved charge transport performance and suppressed carrier recombination, the short‐circuit current density and fill factor of the D18/L8‐BO quasi‐bulk heterojunction organic solar cells are improved simultaneously, and the power conversion efficiency is boosted significantly from 18.21% to 19.59%. Moreover, the improved photovoltaic performance is further verified in D18/Y6 and PM6/L8‐BO‐based organic solar cells, which implies the generalizability of the dual additive‐assisted layer‐by‐layer ‐sequential deposition method.

Morphology Optimization by Non-Halogenated and Twisted Volatile Solid Additive for High-Efficiency Organic Solar Cells.

Recently, volatile solid additives have attracted tremendous interest in the field of organic solar cells (OSCs), which can effectively improve device efficiency without sacrificing the reproducibility and stability of the device. However, the structure of reported solid additives is onefold and its working mechanism needs to be further investigated. Herein, a novel non-halogenated and twisted solid additive 1,4-diphenoxybenzene (DPB) is employed to optimize the morphology of the active layer in OSCs. The properties of additive DPB, morphology of active layer, and carrier dynamics behaviors have been systematically investigated through theoretical calculations, in situ and ex situ spectroscopy, grazing-incidence wide-angle X-ray scattering (GIWAXS), and grazing-incidence small-angle X-ray scattering (GISAXS) measurement, as well as ultrafast spectroscopy technology. The results reveal that the twisted additive DPB selectively interacts with acceptor Y6, and thus forms optimized morphology of active layer with increased molecular crystallinity, tight molecular packing, and favorable phase separation. As a result, the optimized devices deliver a remarkable power conversion efficiency (PCE) of 19.04%, which is the highest value for the D18-Cl:N3 system to date. These results demonstrate that non-halogenated and twisted solid additive DPB has broad prospects in the preparation of highly efficient OSCs, providing theoretical and experimental guidance for the development of high-performance solid additives.

Gradual Optimization of Molecular Aggregation and Stacking Enables Over 19% Efficiency in Binary Organic Solar Cells.

Volatile solid additive is an effective and simple strategy for morphology control in organic solar cells (OSCs). The development of environmentally friendly new additives which can also be easily removed without high-temperature thermal annealing treatment is currently a trend, and the working mechanism needs to be further studied. Herein, a highly volatile and non-halogenated solid additive 1-benzothiophene (BBT) is reported to regulate molecular aggregation and stacking of active layer components. According to the film-forming kinetics process, a momentary intermediate phase is formed during spin-coating, which slows down the film-forming process and leads to more ordered molecular stacking in the solid film after introducing solid additive BBT. Subsequently, after solvent vapor annealing (SVA) further treatment, the resultant blend films exhibit a tighter and more ordered molecular stacking. Consequently, the synergistic effect of solid additive BBT and SVA treatment can effectively control morphology of active layer and improve carrier transport characteristics, thereby enhancing the performance of OSCs. Finally, in D18-Cl:N3 system, an impressive power conversion efficiency of 19.53% is achieved. The work demonstrates that the combination of highly volatile solid additives and SVA treatment is an effective morphology control strategy, guiding the development of efficient OSCs.

Impact of Alkoxy Side Chains on the Quinoxaline-Based Electron Acceptors for Efficient Organic Solar Cells.

In this work, three alkoxy-substituted quinoxaline core-based small-molecule acceptors (BQO-F, BQDO-F, and BQDO-Cl) are developed to elucidate the impact of ethoxy substituents on the physicochemical and photoelectric properties. Comparative analysis reveals that dialkoxy-substituted BQDO-F has a more planar molecular skeleton, a red-shifted absorption spectrum, upshifted energy levels, stronger crystallinity, and reduced energetic disorder compared to the monoalkoxy-substituted BQO-F. Although the replacement of fluorine atoms with chlorine atoms on the end-capped units of BQDO-F leads to a bathochromically shifted absorption spectrum, the resulting molecule BQDO-Cl shows worse π-π packing order compared to BQDO-F. Benefiting from the more favorable active layer morphology and improved carrier dynamics, the PBDB-T:BQDO-F-based organic solar cell achieves a much higher power conversion efficiency (PCE) of 16.41% compared to that of 14.48% obtained in the BQO-F-based device. In comparison with the BQDO-F-based device, the higher voltage loss of the BQDO-Cl-based device results in a lower PCE of 15.89%. The results clarify the effects of ethoxy substituents and end-capped substitutions of quinoxaline core-based small-molecule acceptors on efficient organic solar cells.

Unravel the Distinctive Roles of Liquid and Solid Additives in Blade‐Coated Active Layer for Organic Solar Cell Modules

AbstractAlthough encouraging progress in spin‐coated small‐area organic solar cells (OSCs), reducing efficiency loss caused by differences in film uniformity and morphology when up‐scaled to large‐area modules through meniscus‐guided coating is an important but unsolved issue. In this work, in‐depth research is conducted on the influence of both liquid and solid additives on the film uniformity and morphology of active layer in blade‐coated PM6:L8‐BO binary system. The study reveals that high boiling point liquid additives like 1,8‐diiodooctane (DIO) used in blade‐coating not only delay the volatilization of the solvent but also trigger the Marangoni flow in the same direction as capillary flow, causing excessive aggregation of acceptors, therefore destroying device performance. On the contrary, the solid additive 2‐Iododiphenyl ether (IDPE), which is first reported in this work, can preserve the mechanism for improving device performance while effectively suppressing the excessive aggregation of acceptors during the film‐forming process in blade‐coating from halogen‐free solvent of toluene, resulting in highly homogeneous large‐area active layer films. Consequently, organic solar modules with an impressive efficiency of 15.34% with a total module area of 18.90 cm2 via blade‐coating based on PM6:L8‐BO are achieved. This study not only provides a deep understanding on the effect of liquid and solid additives during blade‐coating from the perspective of fluid mechanisms but also gives a pathway for the development of green solvent printed high‐efficiency OSCs.

Simultaneously Optimizing Molecular Stacking and Phase Separation via Solvent‐Solid Hybrid Additives Enables Organic Solar Cells with over 19% Efficiency†

Comprehensive SummaryGiven the crucial role of film morphology in determining the photovoltaic parameters of organic solar cells (OSCs), solvent or solid additives have been widely used to realize fine‐tuned film morphological features to further improve the performance of OSCs. However, most high‐performance OSCs are processed only using single component additive, either solvent additive or solid additive. Herein, a simple molecular building block, namely thieno[3,4‐b]thiophene (TT), was utilized as the solid additive to coordinate with the widely used solvent additive, 1‐chloronaphthalene (CN), to modulate the film morphology. Systematical investigations revealed that the addition of TT could prevent the excessive aggregation to form a delicate nanoscale phase separation, leading to enhanced charge transport and suppressed charge recombination, as well as superior photovoltaic performance. Consequently, the PM6:Y6 based OSCs with the addition of hybrid additive of CN + TT demonstrated the optimal PCE of 18.52%, with a notable FF of 79.6%. More impressively, the PM6:Y6:PC71BM based ternary OSCs treated with the hybrid additives delivered a remarkable efficiency of 19.05%, which ranks among the best values of Y6‐based OSCs reported so far. This work highlights the importance of the hybrid additive strategy in regulating the active layer morphology towards significantly improved performance.