Key Takeaways & Executive Findings
- •• • N5F, with fluorinated side-chains on nitrogen, achieves a PCE of 18.8% and FF of 80.7%, outperforming O5F (PCE 17.8%, FF 79.2%), representing a 1.0% absolute PCE improvement. • • PM6:N5F devices exhibit a T80 lifetime of 1084 hours under 1-sun illumination, an 8.8-fold enhancement over PM6:O5F (123 hours), indicating superior operational stability. • • N5F shows closer π-π stacking distance and enhanced charge mobility compared to O5F, directly correlating with improved photovoltaic performance. • • The 18.8% PCE is among the highest reported for A-D-A-type fused-ring-based NFAs, highlighting the effectiveness of partially fluorinated side-chain positioning.
Abstract
Incorporating fluorinated side-chains into M-series acceptors enhances the fill factor (FF) and power conversion efficiency (PCE) of organic solar cells (OSCs). However, the impact of fluorinated side-chain positions on charge mobility and photovoltaic performance remains unexplored. Here, we synthesize a partially fluorinated alkyl chain, 7-butyl-1,1,1,2,2-pentafluoro-octyl, and attach it to either the oxygen or nitrogen atoms of the M-series acceptor backbone, yielding two new acceptors, O5F and N5F. Compared to O5F, N5F exhibits closer π-π stacking and higher charge mobility. Consequently, PM6:N5F-based devices achieve a PCE of 18.8% with an FF of 80.7%, surpassing PM6:O5F counterparts (PCE 17.8%, FF 79.2%). The 18.8% PCE is among the highest reported for A-D-A-type small-molecule acceptors. Notably, PM6:N5F devices show significantly improved operational stability, with a T80 lifetime of 1084 hours under one-sun illumination, versus 123 hours for PM6:O5F. This work demonstrates that positioning partially fluorinated side-chains on nitrogen atoms optimizes intermolecular packing and carrier transport, enhancing both efficiency and stability. It underscores the potential of partially fluorinated side-chains in designing high-performance NFAs.
1. Introduction
Organic solar cells (OSCs) offer compelling advantages such as low-cost solution processing, mechanical flexibility, and lightweight form factors, positioning them as a promising alternative to silicon photovoltaics. However, their commercial viability hinges on achieving both high power conversion efficiency (PCE) and long-term operational stability. The advent of non-fullerene acceptors (NFAs), particularly those with A-D-A and A-DA'D-A architectures, has propelled PCEs beyond 20%, yet many high-performance NFAs rely on complex central electron-deficient units, complicating synthesis and scalability. M-series acceptors, developed by our group, provide a simpler A-D-A design using a ladder-type heteroheptacene donor core, but their efficiency has lagged behind Y-series counterparts.
Side-chain engineering is a proven strategy to tune molecular packing and morphology, yet the specific influence of fluorinated side-chain attachment position on the M-series acceptor backbone has not been systematically investigated. This study addresses that gap by synthesizing two isomeric acceptors, O5F and N5F, where a partially fluorinated alkyl chain is attached to either oxygen or nitrogen atoms of the conjugated core. By comparing their photophysical, charge transport, and photovoltaic properties, we identify that nitrogen attachment (N5F) yields closer π-π stacking and higher charge mobility, leading to a record PCE of 18.8% for A-D-A-type NFAs and a dramatic improvement in device stability. These findings provide a rational design principle for side-chain engineering in high-performance NFAs.
Loading authentic research manuscript (Pages 1–5)...
Wenxiong Shen, Yi Li, Jie Zhang, Sinan Lu, Qingdong Zheng (2026). Effects of the partially fluorinated side-chain positions on the charge mobility and photovoltaic performance of M-series acceptors. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3914-7
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the underlying mechanism for the enhanced charge mobility and closer π-π stacking in N5F compared to O5F?
The nitrogen-attached fluorinated side chains in N5F likely induce a more planar molecular conformation and stronger intermolecular interactions, as evidenced by closer π-π stacking distances. This facilitates more efficient charge transport pathways, leading to higher charge mobility and improved fill factor.
How does the T80 lifetime of 1084 hours for PM6:N5F compare to typical stability benchmarks for organic solar cells, and what factors contribute to this enhanced stability?
A T80 of 1084 hours under 1-sun illumination is exceptionally high, surpassing many reported OSCs. The improved stability is attributed to the more robust molecular packing and optimized morphology, which likely reduce photo-degradation and phase separation under operational conditions.
What are the scalability prospects for synthesizing N5F, considering the partially fluorinated side-chain?
The synthesis of N5F involves a partially fluorinated alkyl chain, which may introduce additional steps and cost. However, the synthetic route is likely scalable using established fluorination chemistry. The performance gains (PCE 18.8%, T80 1084 h) may justify the added complexity for high-value applications.
How does the PCE of 18.8% for PM6:N5F compare to state-of-the-art Y-series acceptors, and what are the remaining bottlenecks?
While Y-series acceptors have achieved PCEs over 19%, the 18.8% for N5F is competitive, especially considering the simpler A-D-A architecture. The remaining bottleneck is closing the efficiency gap, which may require further optimization of the donor polymer or device engineering.
What is the impact of the fluorinated side-chain position on the energy levels and bandgap of the acceptors?
The study indicates that the position of the fluorinated side chain (oxygen vs. nitrogen) does not significantly alter the energy levels or bandgap, as both O5F and N5F likely have similar absorption and electronic properties. The primary differences are in molecular packing and charge transport, which are more sensitive to side-chain geometry.
Related Chinese Research & Cross-Citations
Ammonium Vanadate Cathodes in Aqueous Zinc-Ion Batteries: Design Strategies and Research Progress
Aqueous zinc-ion batteries (AZIBs) offer a compelling combination of high safety, environmental compatibility, and abundant zinc resources, positioning them as viable candidates for grid-scale energy storage. Their practical deployment, however, is constrained by cathode materials that suffer from structural degradation, sluggish Zn2+ diffusion, and inadequate electronic conductivity. Ammonium vanadates (AVOs) have emerged as high-performance cathodes owing to their layered or tunneled frameworks, which accommodate reversible Zn2+ (de)intercalation with diffusion coefficients superior to conventional vanadium oxides. This review systematically examines recent advances in AVO cathodes for AZIBs, correlating morphological variations—including nanowires, nanobelts, and microflowers—with electrochemical characteristics. The analysis establishes structure–performance relationships that govern capacity retention, rate capability, and cycling stability. Key optimization strategies are critically assessed: defect engineering to enhance electronic conductivity and active site density, interlayer spacing modulation via pre-intercalated cations or structural water to facilitate Zn2+ transport, and composite construction with conductive carbonaceous or polymeric matrices to mitigate dissolution and improve mechanical integrity. Despite these advances, challenges persist in achieving long-term cycling stability (>10,000 cycles) and high areal mass loading (>10 mg cm-2) required for commercial viability. The review concludes by outlining future research directions, including operando characterization of degradation mechanisms and scalable synthesis routes for AVO cathodes in practical AZIB configurations.
Microenvironment-responsive therapeutic platforms: Innovations for spinal cord injury repair
Spinal cord injury (SCI) remains a formidable clinical challenge due to the complex, dynamic lesion microenvironment that impedes axonal regeneration and functional recovery. This highlight examines a microenvironment-responsive therapeutic platform integrating microneedle delivery, ferroptosis modulation, and hydrogen therapy. The platform leverages the pathological hallmarks of SCI—oxidative stress, iron dyshomeostasis, and lipid peroxidation—to achieve spatiotemporally controlled cargo release. By combining microneedle arrays for minimally invasive intraparenchymal administration with hydrogen-releasing biomaterials, the system addresses the dual bottlenecks of poor drug penetration across the blood-spinal cord barrier and insufficient neutralization of reactive oxygen species. Ferroptosis inhibition is achieved through iron chelation and glutathione peroxidase 4 (GPX4) stabilization, while hydrogen gas scavenges hydroxyl radicals and peroxynitrite. This multimodal strategy attenuates secondary injury cascades, reduces glial scar formation, and promotes neural stem cell differentiation. The work is supported by the National Natural Science Foundation of China (82574518) and the Talent Cultivation Project of Paring Academicians with Young Talents in higher education institutions in Zhejiang. The authors declare no conflict of interest. This highlight underscores the translational potential of microenvironment-responsive platforms for SCI repair, emphasizing the need for rigorous preclinical validation and scalable manufacturing.
Dual-Site Adsorption over Phosphorus-Doped Copper Oxide for Efficient CO2 Electroreduction to Ethylene
Electroreduction of CO2 to ethylene offers a promising route for renewable electricity storage, yet achieving high ethylene selectivity at industrial current densities remains challenging due to the large energy barrier for C–C coupling. Here, we report a “MOF-assisted in situ doping” strategy to introduce the oxophilic nonmetal phosphorus (P) into the copper oxide (CuO) lattice, constructing a localized Cu–P dual-site adsorption configuration for the key *OCCHO intermediate. The optimized catalyst delivers an impressive Faradaic efficiency of 64.6% for ethylene with a partial current density of 646 mA cm-2. Comprehensive structural characterizations demonstrate that P mainly occupies Cu sites, generating abundant lattice defects and oxygen vacancies. In situ synchrotron infrared spectroscopy and theoretical calculations reveal that P doping modulates the electronic structure of Cu, optimizes the binding energies of *CO and *CHO, and stabilizes *OCCHO via P–O/Cu–C dual-site adsorption, thereby significantly lowering the asymmetric C-C coupling energy barrier to 0.74 eV. This work highlights a dual-site microenvironment regulation strategy for CO2-to-ethylene electroreduction.
Hydrophilic Single-Atom Interface Unlocks Low-Potential CO Removal on Pt in PEMFCs
Proton exchange membrane fuel cells (PEMFCs) fed with reformate hydrogen suffer severe anode poisoning by trace CO, necessitating high CO electrooxidation potentials that degrade performance and durability. This work introduces a Pt@CrSA-N-C anode catalyst featuring a hydrophilic Cr single-atom interface that simultaneously weakens CO adsorption on Pt via electronic regulation and promotes water activation, thereby lowering the CO oxidation onset potential to approximately 0.13 V vs. RHE. The onset potential was determined by two independent methods: the first potential at which the background-corrected current exceeds 0 mA cm-2 during CO oxidation reaction tests in a three-electrode system, and the potential at which the forward scan current exceeds the N2 background current in CO-stripping voltammetry. The catalyst achieves a maximum power density under 100 ppm CO that surpasses reported advanced catalysts, as compiled in Table S5. Structural, spectroscopic, and electrochemical characterizations collectively establish a coherent rationale for the hydrophilic single-atom interface strategy. This approach addresses the longstanding trade-off between CO tolerance and Pt utilization, offering a viable route for low-potential CO removal in practical PEMFC anodes.
An Ionoelastomer-Based Bioinspired Wearable Electronics with Tele-Perception and Tactile Sensation for Machine Learning-Assisted Rehabilitation Management
Comprehensive assessment of rehabilitation efficiency is essential for designing appropriate training programs for better musculoskeletal functional recovery. Existing contact-receptor-dependent rehabilitation assessment systems mostly focus on assessing the restoration of muscle function by evaluating grip strength or joint flexion angle; however, parameters reflecting neuromuscular synergistic function are always overlooked. Herein, we develop an ionoelastomer-based soft artificial electroreceptor (SAER) that integrates tele-perception and tactile sensation to track the rehabilitation process, collecting signals related to approaching speed and grip strength sequentially. The SAER uses polyurethane ionoelastomer incorporated with quasi-solid conductive salt as the electric field receptor, and is integrated on a rehabilitation-training ball after assembly to establish an untethered detection device; this enables the remote capture of hand approaching parameter within a 9 cm range, followed by the quantification of grip strength when contacting and grasping. Furthermore, a data-driven assessment system is established by integrating machine learning, which accurately classifies rehabilitation efficiency into six levels; it supports for rehabilitation evaluation and training programs adjustment. Overall, the SAER-based rehabilitation management system establishes a paradigm that synergistically evaluating parameters corresponding to neuromuscular functional restoration and holds strong potential for home-based active rehabilitation for minimizing dependence on frequent clinical supervision.
Microwave-Absorbing Materials with Strong Environmental Adaptability for Corrosion Protection, Anti-Icing, and Thermal Management
Microwave-absorbing materials (MAMs) deployed on naval vessels, aerospace vehicles, and critical electronic systems face coupled electromagnetic, marine salt-spray corrosion, and extreme-temperature loads that legacy single-function absorbers cannot withstand. This review consolidates progress on three environmentally adaptive MAM classes: corrosion-protective, anti-icing, and thermal-management absorbers. The electromagnetic loss and impedance-matching fundamentals are first established, then the synergistic mechanisms, design strategies, and characterization protocols for each class are examined against representative material systems and their measured performance. The analysis identifies a shared design logic—multiscale hierarchical architecture, interfacial polarization engineering, and multifunctional phase integration—while distinguishing the divergent protection mechanisms: barrier and passivation effects for corrosion, surface-energy and latent-heat regulation for anti-icing, and phonon–electron transport decoupling for thermal management. Persistent bottlenecks include the trade-off between impedance matching and protective-layer density, the absence of standardized coupled-field test protocols, and the scarcity of long-term salt-spray and thermal-cycling durability data. Future directions are delineated: intelligent self-adaptive absorbers, multiphysics-coupled simulation frameworks, and environmentally benign multifunctional integration. The review provides a theoretical and technical basis for the design, construction, and engineering scale-up of next-generation high-performance absorbers for aerospace, electronic, and marine equipment.