Morphology Of Films Research Articles

Effect of Hofmeister Anions Series on the Langmuir Film of Tetronic 90R4 and Tetronic 701 Block Copolymers.

The air-water interfacial behavior of Tetronic 90R4 and Tetronic 701 was studied in the presence of sodium salts with different anions namely , , , , Cl-, Br-, , I-, and SCN-. Their presence in the subphase altered the arrangement of both tetronic molecules at the air-water interface. The limiting mean molecular area of the Langmuir film for both tetronics was found to be ion specific; it increased following the series < < < < Cl-< Br-< < I-< SCN-, which was found to be aligned with the Hofmeister series of anions. Furthermore, the study explored the effects of the hydration enthalpy, free energy, viscosity BJD coefficient, and polarizability of these anions on the interfacial behavior of tetronics. The Langmuir-Blodgett film morphology was also examined in the presence of these salt species using SEM. Morphologies were explained considering kosmotropic and chaotropic nature of these anions.

Stretchable Composite Films Are Prepared by Using Cellulose Pulp with Differential Substitution of Carboxymethyl Cellulose and Thymol with an Infrared Heating Process for Packaging Application.

Herein, cellulose pulp (CP), carboxymethyl cellulose (CMC), and thymol-based eco-friendly, transparent, and flexible composite films are prepared. These materials dissolved well in an environment-friendly process in N-methyl morpholine N-oxide (NMMO) ionic liquids using infrared heating. Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses are used to study the structure, microstructure, and morphology of the composite films. The thermal properties of the CP/CMC/thymol composites are thoroughly studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The thermal stability of the composites (T 5%-57.8-91.2 °C and T 10%-216.6-284.1 °C) significantly improves following the CMC addition. In each case, all the composite film exhibits unique T g (140.5-143.1 °C) values, as confirmed by DSC. The tensile strength of the cellulose pulp is 66.5 MPa, increasing to 78.4 MPa for the CP/CMC-1:0.5 composites and steadily increasing to 93.8 MPa with increasing CMC content. Similarly, CMC increases the EB of cellulose pulp from 9.3 to 7.4%. The water vapor permeability and swelling ratio values of the CP/CMC/thymol composites are in the range of 1.9-2.11 × 10-9 g/(m2·Pa·s) and 52.5-50.8° respectively. The CP, CMC, and thymol-based composite do not exhibit cytotoxicity to the aneuploid immortal keratinocyte cell line and demonstrate excellent antioxidant properties, for promising packaging and biomedical applications.

Engineering Thermoresponsive Poly(N-isopropylacrylamide)-Based Films with Enhanced Stability and Reusability for Efficient Bone Marrow Mesenchymal Stem Cell Culture and Harvesting.

Poly(N-isopropylacrylamide) (PNIPAM) offers a promising platform for non-invasive and gentle cell detachment. However, conventional PNIPAM-based substrates often suffer from limitations including limited stability and reduced reusability, which hinder their widespread adoption in biomedical applications. In this study, PNIPAM copolymer films were formed on the surfaces of glass slides or silicon wafers using a two-step film-forming method involving coating and grafting. Subsequently, a comprehensive analysis of the films' surface wettability, topography, and thickness was conducted using a variety of techniques, including contact angle analysis, atomic force microscopy (AFM), and ellipsometric measurements. Bone marrow mesenchymal stem cells (BMMSCs) were then seeded onto PNIPAM copolymer films prepared from different copolymer solution concentrations, ranging from 0.2 to 10 mg·mL-1, to select the optimal culture substrate that allowed for good cell growth at 37 °C and effective cell detachment through temperature reduction. Furthermore, the stability and reusability of the optimal copolymer films were assessed. Finally, AFM and X-ray photoelectron spectroscopy (XPS) were employed to examine the surface morphology and elemental composition of the copolymer films after two rounds of BMMSC adhesion and detachment. The findings revealed that the surface properties and overall characteristics of PNIPAM copolymer films varied significantly with the solution concentration. Based on the selection criteria, the copolymer films derived from 1 mg·mL-1 solution were identified as the optimal culture substrates for BMMSCs. After two rounds of cellular adhesion and detachment, some proteins remained on the film surfaces, acting as a foundation for subsequent cellular re-adhesion and growth, thereby implicitly corroborating the practicability and reusability of the copolymer films. This study not only introduces a stable and efficient platform for stem cell culture and harvesting but also represents a significant advance in the fabrication of smart materials tailored for biomedical applications.

Impact of Silver Incorporation and Flash-Lamp-Annealing on the Photocatalytic Response of Sputtered ZnO Films.

Thin films of silver-doped zinc oxide (SZO) were deposited at room temperature using a DC reactive magnetron co-sputtering technique using two independent Zn and Ag targets. The crystallographic structure, chemical composition and surface morphology of SZO films with different silver concentrations were correlated with the photocatalytic (PC) properties. The crystallization of the SZO films was made using millisecond range flash-lamp-annealing (FLA) treatments. FLA induces significant structural ordering of the wurtzite structure and an in-depth redistribution of silver, resulting in the formation of silver agglomerates. The wurtzite ZnO structure is observed for silver contents below 10 at.% where Ag is partially incorporated into the oxide matrix, inducing a decrease in the optical band-gap. Regardless of the silver content, all the as-grown SZO films do not exhibit any significant PC activity. The best PC response is achieved for samples with a relatively low Ag content (2-5 at.%) after FLA treatment. The enhanced PC activity of SZO upon FLA can be attributed to structural ordering and the effective band-gap narrowing through the combination of silver doping and the plasmonic effect caused by the formation of Ag clusters.

Synthesis and characterization of zinc cobalt sulphide nanofilms for optoelectronic applications

Zinc-cobalt sulphide (ZnxCo1−xS) thin films were fabricated on glass substrates using the chemical bath deposition (CBD) technique. In this study, the films were grown employing solutions of zinc acetate, cobalt sulphate, and thioacetamide as the respective sources of zinc, cobalt, and sulphur. The synthesized films were investigated for their potential use in optoelectronic device applications. Optical characterization revealed that the films exhibited a direct transition with an energy gap ranging from 3.350 to 3.360 ​eV. As the zinc concentrations were changing, the absorbance of the films were decreasing uniformly along the wavelength spectra. The films exhibit a low extinction coefficient (0.0–0.23) that may be due to the internal reflections within the material as concentrations changes. Variations in the thickness, reflectance and refractive index with zinc concentrations were also discussed. The electrical resistivity was found to decrease from 7.12×108 to 5.94×108 (Ω.cm) with zinc concentrations. According to the crystallography spectrum, ZnxCo1−xS has a polycrystalline structure with various distinct peaks at different orientations. Scanning electron microscopy shows that surface morphology of ZnxCo1−xS films has a well-defined nanoparticles of different shapes and sizes which are uniformly distributed and are significantly transformed as a function of concentrations. The results demonstrate that the chemically deposited thin films can be engineered for a range of optoelectronic applications.

Investigation of thermally induced surface composition and morphology variation of magnetron sputtered Sb2Se3 absorber layer for thin film solar cells

One of the most promising semiconductor materials for the development of sustainable thin-film solar cell technology is antimony selenide (Sb2Se3). Its excellent optical and electrical properties have drawn attention lately for potential application in thin-film solar cells. In this study, Sb2Se3 films deposited using the direct current (DC) magnetron sputtering technique have been subjected to a post-annealing process without an extra selenium supply at temperatures between 150 and 450 °C. Without an extra selenium supply, the impact of post-annealing temperature on the surface composition as well as the physical properties of the fabricated films was investigated. The overall evaluations revealed that the post-annealing temperature is highly efficient in altering the physical properties of the Sb2Se3 absorber thin films. We further observed that the post-annealing process improved the crystallization and the heat treatment temperature quite affected preferential orientation. The surface morphology of films exhibited structural deformation at high post-annealing temperatures (> 350 °C). According to optical and electrical characterizations, respectively, the optical energy gap and the resistivity of Sb2Se3 films reduced with an increment in the post-annealing temperature. Based on the XPS result, the variation in temperature of post-annealing led to a change in the surface composition of the films. The findings on the growth of Sb2Se3 thin films indicate the existence of an intermediate growth temperature that permits the growth of Sb2Se3 films to be optimized. The study’s conclusions can serve as a guide to the growth of Sb2Se3 thin films with the desired crystallinity, surface morphology, and composition for thin film solar cell applications.

Fabrication and Self-Assembly Behavior of BPEF and BBPEF Composite Langmuir-Blodgett Films with Photovoltaic Conversion Properties.

The LB films prepared through the Langmuir-Blodgett (LB) technique are of significant importance for the fabrication of functional films such as optoelectronic materials and sensors. In this study, 9,9-bis (4-(2-hydroxy-ethoxy) phenyl) fluorene (BPEF) and 9,9-bis [3-phenyl-4-(β-hydroxy-ethoxy) phenyl] fluorene (BBPEF) were combined with saffron T (ST), methylene blue (MB) and Rhodamine B (RhB) dyes by LB technique to prepare ordered composite films. The nanostructures and morphologies of the composite films were analyzed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). It was found that the films exhibited distinct aggregation morphologies. The UV-VIS absorption spectra showed that the concentration of dye molecules had a significant effect on the spectral characteristics. The contact Angle test shows that the prepared composite films are hydrophobic. The photovoltaic conversion performance of LB composite films was studied by transient photocurrent response experiments. It was found that BPEF/dye and BBPEF/dye composite films exhibited significant responses in photocurrent. In particular, BPEF/RhB and BBPEF/RhB composite films demonstrated excellent photoresponsive performance. This study used LB technology in combination with BPEF and BBPEF to demonstrate enhanced photocurrent and stable performance of LB film, which provided ideas for expanding the application range of materials.

Enhanced Performance and Stability of Perovskite Solar Cells Through Surface Modification with Benzocaine Hydrochloride.

Current development of inverted p-i-n perovskite solar cells (PSCs), with nickel oxide as the hole transport layer, is progressing toward lower net costs, higher efficiencies, and superior stabilities. Unfortunately, the high density of defect-based traps on the surface of perovskite films significantly limits the photoelectric conversion efficiency and operational stability of perovskite solar cells. Finding cost-effective interface modifiers is crucial for the further commercial development of p-i-n PSCs. In the present work, we report a passivation strategy using a multifunctional molecule, benzocaine hydrochloride (BHC), which is shown to reduce defect density and enhance the photovoltaic performance and stability of the resultant p-i-n PSCs. It has been revealed that BHC strongly interacts with perovskite precursor components and triggers the evolution of the perovskite absorber film morphology and enables improved surface energy level alignment, thus promoting charge carrier transport and extraction. These properties are beneficial for improving open-circuit voltage (VOC) and fill factor (FF). Our results show that the photoelectric conversion efficiency (PCE) of p-i-n PSCs with nickel oxide as the hole transport layer increased from an initial 20.0% to 22.1% after being passivated with BHC, and these passivated devices also exhibited improved stability. DFT calculations reveal the unusual ability of the BHC passivant to improve band alignment while also preventing the accumulation of holes at the interface. In this work, the advantages of BHC passivation are demonstrated by linking theoretical calculations with optical and electrical characterizations.

Interdependence of Support Wettability ‐Electrodeposition Rate ‐ Sodium Metal Anode and SEI Microstructure

This study examines how current collector support chemistry (sodiophilic intermetallic Na2Te vs. sodiophobic baseline Cu) and electrodeposition rate affect microstructure of sodium metal and its solid electrolyte interphase (SEI). Capacity and current (6 mAh cm‐2, 0.5‐3 mA cm‐2) representative of commercially relevant mass loading in anode‐free sodium metal battery (AF‐SMBs) are analyzed. Synchrotron X‐ray nanotomography and grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) are combined with cryogenic focused ion beam (cryo‐FIB) microscopy. Highlighted are major differences in film morphology, internal porosity, and crystallographic preferred orientation e.g. (110) vs. (100) and (211) with support and deposition rate. Within the SEI, sodium fluoride (NaF) is more prevalent with Te‐Cu versus sodium hydride (NaH) and sodium hydroxide (NaOH) with baseline Cu. Due to competitive grain growth the preferred orientation of sodium crystallites depends on film thickness. Mesoscale modelling delineates the role of SEI (ionic conductivity, morphology) on electrodeposit growth and onset of electrochemical instability.

Exploring the Impact of 1,8-Diioodoctane on the Photostability of Organic Photovoltaics.

Improving the photostability of the light-harvesting blend film in organic photovoltaics is crucial to achieving long-term operational lifetimes that are required for commercialization. However, understanding the degradation factors which drive instabilities is complex, with many variables such as film morphology, residual solvents, and acceptor or donor design all influencing how light and oxygen interact with the blend film. In this work, we show how blend films comprising a donor polymer (PBDB-T) and small molecule acceptor (PC71BM or ITIC) processed with solvent additive (DIO) yield very different film morphologies, device performance, and photostability. We show that DIO is retained approximately 10 times more effectively in ITIC based films compared to PC71BM. Unexpectedly, we see that while high volumes of DIO reduce photostability for encapsulated ITIC devices, when oxygen is introduced DIO can improve the lifetime of PBDB-T:ITIC based cells. Here, the addition of 3% DIO doubles the T 80 compared to ITIC based devices without DIO, suggesting that DIO-induced morphological changes interfere with or reduce photo-oxidative reactions.

Enhancing electric field intensity of interfacial electric double layer to improve properties of solid electrolyte interface for sodium-ion batteries

The electrical double layer (EDL) provides a critical area, where the specific adsorption on the electrode dominates the initial structure and chemical composition of the solid electrolyte interface (SEI) film. Therefore, the SEI can be optimized by adjusting the properties of the EDL. Here, we regulate the properties of EDL to optimize the composition and morphology of the SEI film on the hard carbon anode surface by adding NaF with small molecule structure. The preferential accumulation of NaF additives on the electrode surface enhances the electric field intensity and promotes electrolyte decomposition. That is, the formed SEI film rich in inorganic NaF and B-O components, can significantly improve the storage capacity of sodium ions in the hard carbon anode and accelerate the rapid transport of sodium ions. This strategy enables the cycling capacity to improve by 13.5 %, and maintain a stable capacity retention rate of 86.2 % at the rate of 1C after 500 cycles, thereby extending the lifespan and increasing the capacity of the rechargeable battery. The strategy that utilizing small molecule additives to enhance the electric field intensity of EDL provides a new approach to improve the performances of SEI film and battery performances.

Stable and sustainable perovskite solar modules by optimizing blade coating nickel oxide deposition over 15 × 15 cm2 area

Perovskite solar cells have rapidly advanced, achieving over 26% power conversion efficiency on the laboratory scale. However, transitioning to large-scale production remains a challenge due to limitations in conventional fabrication methods like spin coating. Here, we introduce an optimized blade coating process for the scalable fabrication of large-area (15 cm × 15 cm) perovskite solar modules with a nickel oxide hole transport layer, performed in ambient air and utilizing a non-toxic solvent system. Self-assembled monolayers between the nickel oxide and perovskite layer improve the uniformity and morphology of the perovskite film. Perovskite solar modules with a 110 cm2 active area achieve a power conversion efficiency of 12.6%. Moreover, encapsulated modules retained 84% of their initial efficiency after 1,000 hours at 85 °C in air (ISOS-T-1). This study demonstrates progress in the large-scale production of perovskite solar cells that combine efficiency with long-term stability.

Angular- and polarization-insensitive free-standing graphene oxide films for broadband light absorbing applications

Free-standing graphene oxide (FSGO)-based films with angular and polarization insensitivities are demonstrated for broadband absorption applications. The modified Hummers’ method was used to prepare the GO powder. An easily scalable process (evaporation-induced self-assembly) was used to synthesize the FSGO films. The FSGO broadband absorbers with omni-direction and polarization-independent nature was achieved by varying the GO concentrations. The FSGO films were prepared at different GO concentrations to achieve different thicknesses (2–15 μm). The FSGO film with the highest GO concentration (∼10 mg/ml) exhibited high absorptance (α = 0.91) in the broadband region (i.e., 250–2500 nm). The transition from narrow band absorber to a broadband absorber is achieved by varying the GO concentration. The optimized FSGO film (8 mg/ml) shows α of 0.91 with angular and polarization-insensitivity in the visible region. At concentrations <8 mg/ml, the FSGO films are translucent and do not exhibit broadband absorption behavior. Spectroscopic ellipsometry measurements indicate the low refractive index nature of the FSGO films (n = 1.7–1.2 at 400–800 nm). The low refractive index combined with the unique surface morphology of the FSGO films resulted in broadband absorption. Optical simulations were performed to validate the absorption mechanism of the FSGO films.

Enhancement of Tribological Performance of PTFE/aramid Fabric Liner under High-Temperature and Heavy-Load through Incorporation of Microcapsule/CF Multilayer Composite Structure

Liners suffer from low service life under high-temperature and heavy-load conditions, hindering their widespread use in aerospace applications. A novel strategy of incorporating polyaryl ether sulfone/polymethylphenlsiloxane (PES/PMPS) microcapsules and carbon fibers (CFs) into the polytetrafluoroethylene (PTFE)/aramid fabric liner was used. At the micro-scale level, the worn surface morphology and the transfer film morphology were analyzed to reveal the tribological mechanisms. At the nano-scale level, molecular dynamics simulation was used to analyze the formation mechanism of the transfer film. The results showed that the friction coefficient and wear rate of the liner with microcapsule/CF multilayer structure were reduced by 17% and 24%, respectively. The incorporation of microcapsule/CF multilayer structure can be effectively applied to enhance the tribological performance of liners in harsh operating conditions.

Hybrid System of Polystyrene and Semiconductor for Organic Electronic Applications

While organic semiconductors hold significant promise for the development of flexible, lightweight electronic devices such as organic thin-film transistors (OTFTs), photodetectors, and gas sensors, their widespread application is often limited by intrinsic challenges. In this article, we first review these challenges in organic electronics, including low charge carrier mobility, susceptibility to environmental degradation, difficulties in achieving uniform film morphology and crystallinity, as well as issues related to poor interface quality, scalability, and reproducibility that further hinder their commercial viability. Next, we focus on reviewing the hybrid system comprising an organic semiconductor and polystyrene (PS) to address these challenges. By examining the interactions of PS as a polymer additive with several benchmark semiconductors such as pentacene, rubrene, 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene), 2,8-difluoro-5,11-bis(triethylsilylethynyl) anthradithiophene (diF-TES-ADT), and 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT), we showcase the versatility of PS in enhancing the crystallization, thin film morphology, phase segregation, and electrical performance of organic semiconductor devices. This review aims to highlight the potential of an organic semiconductor/PS hybrid system to overcome key challenges in organic electronics, thereby paving the way for the broader adoption of organic semiconductors in next-generation electronic devices.

Tuning surface morphology of AuNPs film via thiourea as a stable SERS platform for methylene blue

Gold nanoparticles (AuNPs) have been extensively utilized in various fields such as sensors, life sciences, and catalysis. In this study, AuNPs were synthesized using a reduction method and subsequently treated with thiourea in an ethanol-water environment to prepare AuNPs film using a centrifugal deposition method for first time, resulting in the aggregation of the initial small-sized AuNPs into larger microsphere-like structures. The addition of thiourea facilitated the interconnection between AuNPs, ultimately leading to the formation of large stable gold microspheres. The sheet resistance of the AuNP films transitioned from being non-conductive to exhibiting a sheet resistance of 42.6 Ω/sq following thiourea treatment. The transformation from a flat surface to tightly connected particles resembling microspheres was observed from SEM images. The thiourea treatment not only altered the morphological characteristic of the AuNPs films but also significantly increased the number of scattering sites on their surface, leading to a substantial enhancement in the Raman scattering effect for methylene blue. This structural configuration also improved the electronic conduction and stability of the treated AuNPs films. Consequently, these findings suggest that AuNPs have promising application prospects in surface-enhanced Raman scatting (SERS), as well as in flexible electronics, catalysis, adsorption, and energy fields.

Achieving stable organic solar cells with 19.2 % efficiency via fine interpenetrating network with fused-ring aromatic lactone donor

The ternary strategy has enhanced the power conversion efficiency (PCE) of organic solar cells. However, long-term stability remains a challenge due to heat-induced molecular interactions and excessive self-aggregation. The fused-ring aromatic lactone (FAL) unit, with its extended molecular plane and electron-withdrawing ability, acts as an ideal building block in our newly designed donor P35. By introducing P35 into PM6:L8-BO systems, it optimizes film morphology and enhances π-π stacking, facilitating phase separation and balancing charge transport channels. The electron-withdrawing capability of P35 lowers the HOMO levels, thereby decreasing non-radiative recombination. Additionally, the extended molecular plane of P35 provides structural support to prevent the collapse of fiber-like PM6 and crosslinks with PM6 to form a thermodynamically stable interpenetrating network. This effectively limits the formation of isolated SMA islands, thereby minimizing the degeneration of the active layer. Consequently, an optimized PCE of 19.2 % (certified 18.55 %) is achieved in the PM6:P35:L8-BO devices, which still retains 80 % initial PCE under 600 h of AM 1.5 G illumination and 90 % PCE after 950 h storage in darkness. This research emphasizes the importance of electron-withdrawing capabilities and extended molecular planes in achieving long-term stability and high efficiency.

Recent Progress and Applications of NanoIR‐AFM in Morphological Characterization of Organic Solar Cells

AbstractOrganic solar cells (OSCs) are gaining attention in building‐integrated and agricultural photovoltaics due to their light weight, mechanical flexibility, and low‐cost solution processability. To achieve commercial viability, understanding the relationships between active layer material structure, film morphology, and photovoltaic performance is crucial. Nanoscale infrared spectroscopy coupled with atomic force microscopy (nanoIR‐AFM) offers an advanced characterization of active layer morphology at high resolution to help understand OSC performance. This review outlines recent developments and applications of nanoIR‐AFM in OSC research, detailing its principles, instruments, and functions. Strategies to enhance OSC performance and their morphological characterization by nanoIR‐AFM are discussed, offering insights into active layer evolution and device performance. The review highlights challenges faced by nanoIR‐AFM in OSC applications and highlights its potential role in advancing OSC technology. As nanoIR‐AFM continues to evolve, it will play a critical role in OSC development, providing essential technical means for further progress.

Synergistic design of processable Nb2O5-TiO2 bilayer nanoarchitectonics: enabling high coloration efficiency and superior stability in dual-band electrochromic energy storage

This paper introduces a proof of concept for a dual-band electrochromic (EC) device to modulate solar light transmission across visible and near-infrared regions selectively. EC materials based on ion insertion/extraction mechanisms also present the possibility for energy storage, widening its functionality to the supercapacitor platform. The bi-functional performance of dual-band radiation control and energy storage was achieved by exploiting two earth-abundant metal oxides that could absorb two different spectral regions when electrochemically charged. The bilayer structure was prepared using a one-step hydrothermal method, which produced Nb2O5-TiO2 bilayer on fluorine-doped tin oxide (FTO) conducting glass substrates. The nano-dimensions of the active materials endorse the development of high-transparency thin film under open circuit conditions. The variations in the TiO2 annealing temperature influence the crystallinity and surface morphology of the thin films, which influence the performance of dual-band EC energy storage. The well-optimized NT-500 sample facilitated exclusive electron-charge transport, producing excellent electrochemical performance in dual-band EC and energy storage. A large optical modulation of 80.4 % and 89.8 % at 600 nm and 800 nm (near-infrared) was achieved with an enhanced areal capacitance of 88.1 mF/cm2 and excellent cycling stability after continuous coloring/bleaching cycles for 18,000 s. This paper presents a prototype bi-functional device based on NT-500, which showed independent control and modulation of visible and near-infrared transmittance. Notably, the device retained excellent energy storage performance alongside its advanced optical functionalities. This bilayer nanostructure capitalizes on the inherent electrochemical properties of both materials and introduces novel features that can potentially revolutionize the platform of EC-energy storage.

Delicate Regulation of Central Substituents Boosts Organic Photovoltaic Performance of Dimeric Acceptors.

Dimeric acceptors are expected to satisfy both excellent power conversion efficiency (PCE) and operational stability of organic solar cells (OSCs). However, comparing to highly planar and symmetrical monomer-like acceptors, the quite different steric/spatial configurations of dimeric acceptors affect device outcomes greatly. Herein, on basis of the same dimeric molecular platform that constructed by bridging central units of two monomer-like acceptor, diverse substituents (─OCH3 for D1, ─CH3 for D2, and ─CF3 for D3) are grafted on central units to regulate the three dimensions (3D) geometries of dimeric acceptors delicately. A systematic investigation reveals the substituent-dependent variation of energy level, absorption, and molecular packing behavior. Consequently, D2 acceptor, characteristic of more favorable configuration, affords a superior film morphology and charge transfer/transport dynamics in resulting OSCs, thus yielding an excellent PCE of 17.50% along with a good long-term stability. This work manifests the crucially important role of central substituents in constructing high-performance dimeric acceptors.