DIET-like and MIET-like mutualism of S. oneidensis MR-1 and metal-reducing function microflora boosts Cr(VI) reduction.

Microbial treatment of Cr(VI) is an environmentally friendly and low-cost approach. However, the mechanism of mutualism and the role of interspecies electron transfer in Cr(VI) reducing microflora are unclear. Herein, we constructed an intersymbiotic microbial association flora to augment interspecies electron transfer via functionalizing electroactive Shewanella oneidensis MR-1 with metal-reducing microflora, and thus the efficiency of Cr(VI) reduction. The findings suggest that the metal-reducing active microflora could converts glucose into lactic acid and riboflavin for S. oneidensis MR-1 to act as a carbon source and electron mediator. Thus, when adding initial 25 mg/L Cr (VI), this microflora exhibited an outstanding Cr (VI) removal efficiency (100%) at 12 h and elevated Cr (III) immobilization efficiency (80%) at 60 h with the assistance of 25 mg/L Cu(II). A series of electrochemical experiments proved this remarkable removal efficiency were ascribed to the improved interspecies electron transfer efficiency through direct interspecies electron transfer and riboflavin through mediated interspecies electron transfer. Furthermore, the metagenomic analysis revealed the expression level of the electron transport pathway was promoted. Intriguing high abundance of genes participating in the bio-reduction and biotransformation of Cr(VI) was also observed in functional microflora. These outcomes give a novel strategy for enhancing the reduction and fixation of harmful heavy metals by coculturing function microflora with electrogenic microorganisms.

Enhancing the extracellular electron transfer ability via Polydopamine@S. oneidensis MR-1 for Cr(VI) reduction.

Microbial reduction of hexavalent chromium (Cr (VI)) shows better efficiency and cost-effectiveness. However, immobilization of Cr (III) remains a challenge as there is a limited supply of electron donors. A greener and cleaner option for donating external electrons was using bioelectrochemical systems to perform the microbial reduction of Cr(VI). In this system, we constructed a polydopamine (PDA) decorated Shewanella oneidensis MR-1 (S. oneidensis MR-1) bioelectrode with bidirectional electron transport, abbreviated as PDA@S. oneidensis MR-1. The conjugated PDA distributed on the intracellular and extracellular of individual S. oneidensis MR-1 has been shown to accelerate electron transfer by outer membrane C-type cytochromes and flavin-bound MtrC/OmcA pathway by various electrochemical analyses. As expected, the PDA@S. oneidensis MR-1 biofilm achieved 88.1% Cr (VI) removal efficiency (RE) and 58.1% Cr (III) immobilization efficiency (IE) within 24 h under the autotrophic conditions at the optimal voltage (-150 mV) compared with the control potential (0 mV). The PDA@S. oneidensis MR-1 biofilm showed increased RE activity was attributed to the shortening of the distance between individual bacteria by PDA. This research provides a viable strategy for in situ bioremediation of Cr(VI) polluted aquatic environment.

Boosting bioelectricity generation in microbial fuel cells via biomimetic Fe-N-S-C nanozymes.

Anode performance has been regarded as a crucial factor determining long-term stability and electricity generation of microbial fuel cells (MFCs), which restricts by the difficult extracellular electron transfer (EET) on the microbe/anode interface. Herein, inspired by biological enzyme systems, this study synthesized the biomimetic nanozymes with Fe-N-S-C active sites as the anode materials of MFCs, which was similar to the hemes of c-type cytochromes (c-Cyts) for boosting EET process. As excepted, an obviously faster start-up and a much higher power density were achieved by the MFCs equipped with Fe-N-S-C nanozymes (startup time, 3.5 d; power density, 2366 ± 34 mW m-2) than that based on traditional carbon cloth (startup time, 5.6 d; power density, 1009 ± 26 mW m-2). Such unique features of Fe-N-S-C nanozymes anode not only greatly favored the bacterial adhesion and the electroactive bacteria enrichment on the anode surface, but also efficiently facilitated the EET process between the electroactive bacteria and anode surface. This study provided a feasible strategy for designing the novel MFC anode materials from the perspective of bionic enzyme.

Effects of enzymes on organic matter conversion in anaerobic fermentation of sludge to produce volatile fatty acids.

Sludge hydrolysis is a vital step in anaerobic digestion of sludge. This study compared the efficacy of free versus immobilized enzymes at different concentrations in promoting sludge disintegration. Pretreatment with 1,000 mg/L immobilized enzymes was more efficient in promoting sludge disintegration than free enzymes at the same concentration. Under the optimized conditions, volatile fatty acids (VFAs) were produced at 10.6 g/L, accounting for 85 % of total soluble chemical oxygen demand. Improved VFA production was attributed to the release of large amounts of polysaccharides and proteins from the enzymatically pretreated sludge. Released organic matter are the substrates for VFAs generated by the determined microbial community of Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, and Chloroflexi. In this study, anaerobic fermentation was used to successfully convert organic matter in sludge into high-value-added VFAs. Therefore, this process can be selected as a strategy to reduce carbon emissions from wastewater treatment plants (WWTPs).

Quasi-Homojunction Organic Nonfullerene Photovoltaics Featuring Fundamentals Distinct from Bulk Heterojunctions.

In contrast to classical bulk heterojunction (BHJ) in organic solar cells (OSCs), the quasi-homojunction (QHJ) with extremely low donor content (≤10 wt.%) is unusual and generally yields much lower device efficiency. Here, representative polymer donors and nonfullerene acceptors are selected to fabricate QHJ OSCs, and a complete picture for the operation mechanisms of high-efficiency QHJ devices is illustrated. PTB7-Th:Y6 QHJ devices at donor:acceptor (D:A) ratios of 1:8 or 1:20 can achieve 95% or 64% of the efficiency obtained from its BHJ counterpart at the optimal D:A ratio of 1:1.2, respectively, whereas QHJ devices with other donors or acceptors suffer from rapid roll-off of efficiency when the donors are diluted. Through device physics and photophysics analyses, it is observed that a large portion of free charges can be intrinsically generated in the neat Y6 domains rather than at the D/A interface. Y6 also serves as an ambipolar transport channel, so that hole transport as also mainly through Y6 phase. The key role of PTB7-Th is primarily to reduce charge recombination, likely assisted by enhancing quadrupolar fields within Y6 itself, rather than the previously thought principal roles of light absorption, exciton splitting, and hole transport.

Reducing Energy Disorder in Perovskite Solar Cells by Chelation.

In inverted perovskite solar cells (PSCs), the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is a widely used electron transport material. However, a high degree of energy disorder and inadequate passivation of PCBM limit the efficiency of devices, and severe self-aggregation and unstable morphology limit the lifespan of devices. Here, we design a series of fullerene dyads FP-Cn (n = 4, 8, 12) to replace PCBM as an electron transport layer, where [60]fullerene is linked with a terpyridine chelating group via a flexible alkyl chain of different lengths as a spacer. Among three fullerene dyads, FP-C8 shows the most enhanced molecule ordering and adhesion with the perovskite surface due to the balanced decoupling between the chelation effect from terpyridine and the self-assembly of fullerene, leading to lower energy disorder and higher morphological stability relative to PCBM. The FP-C8/C60-based devices using Cs0.05FA0.90MA0.05PbI2.85Br0.15 as a light absorber show a power conversion efficiency of 21.69%, higher than that of PCBM/C60 (20.09%), benefiting from improved electron extraction and transport as well as reduced charge recombination loss. When employing FAPbI3 as a light absorber, the FP-C8/C60-based devices exhibit an efficiency of 23.08%, which is the champion value of inverted PSCs with solution-processed fullerene derivatives. Moreover, the FP-C8/C60-based devices show better moisture and thermal stability than PCBM/C60-based devices and maintain 96% of their original efficiency after 1200 h of operation, while their counterpart PCBM/C60 maintains 60% after 670 h.

Aptasensors for mycotoxins in foods: Recent advances and future trends.

Mycotoxin contamination in foods has posed serious threat to public health and raised worldwide concern. The development of simple, rapid, facile, and cost-effective methods for mycotoxin detection is of urgent need. Aptamer-based sensors, abbreviated as aptasensors, with excellent recognition capacity to a wide variety of mycotoxins have attracted ever-increasing interest of researchers because of their simple fabrication, rapid response, high sensitivity, low cost, and easy adaptability for in situ measurement. The past few decades have witnessed the rapid advances of aptasensors for mycotoxin detection in foods. Therefore, this review first summarizes the reported aptamer sequences specific for mycotoxins. Then, the recent 5-year advancements in various newly developed aptasensors, which, according to the signal output mode, are divided into electrochemical, optical and photoelectrochemical categories, for mycotoxin detection are comprehensively discussed. A special attention is taken on their strengths and limitations in real-world application. Finally, the current challenges and future perspectives for developing novel highly reliable aptasensors for mycotoxin detection are highlighted, which is expected to provide powerful references for their thorough research and extended applications. Owing to their unique advantages, aptasensors display a fascinating prospect in food field for safety inspection and risk assessment.

A CdSe@CdS quantum dots based electrochemiluminescence aptasensor for sensitive detection of ochratoxin A.

In this work, a CdSe@CdS quantum dots (QDs) based label-free electrochemiluminescence (ECL) aptasensor was developed for the specific and sensitive detection of ochratoxin A (OTA). Chitosan (CHI) could immobilize abundant QDs on the surface of an Au electrode as the luminescent nanomaterials. Glutaraldehyde was used as the crosslinking agent for coupling a large number of OTA aptamers. Thanks to the excellent stability, good biocompatibility, and strong ECL intensity of CdSe@CdS QDs, as well as the quick reactions of the generated SO4•- in the electrolyte, strong ECL signals were measured. Because of the specific recognition of aptamer toward OTA, the reduced ECL signals caused by OTA in the samples were recorded for quantify the content of OTA. After optimizing a series of crucial conditions, the ECL aptasensor displayed superior sensitivity for OTA with a detection limit of 0.89 ng/mL and a wide linear concentration range of 1-100 ng/mL. The practicability and viability were verified through the rapid and facile analysis of OTA in real Lily and Rhubarb samples with recovery rates (n = 3) of 98.1-105.6% and 97.3-101.5%, respectively. The newly-developed QDs-based ECL aptasensor provided a new universal analytical tool for more mycotoxins in safety assessment of foods and feeds, environmental monitoring, and clinical diagnostics.

Recent advances in synthesis and modification of carbon dots for optical sensing of pesticides.

Serious threat from pesticide residues to the ecosystem and human health has become a global concern. Developing reliable methods for monitoring pesticides is a world-wide research hotspot. Carbon dots (CDs) with excellent photostability, low toxicity, and good biocompatibility have been regarded as the potential substitutes in fabricating various optical sensors for pesticide detection. Based on the relevant high-quality publications, this paper first summarizes the current state-of-the-art of the synthetic and modification approaches of CDs. Then, a comprehensive overview is given on the recent advances of CDs-based optical sensors for pesticides over the past five years, with a particular focus on photoluminescent, electrochemiluminescent and colorimetric sensors regarding the sensing mechanisms and design principles by integrating with various recognition elements including antibodies, aptamers, enzymes, molecularly imprinted polymers, and some nanoparticles. Novel functions and extended applications of CDs as signal indicators, catalyst, co-reactants, and electrode surface modifiers, in constructing optical sensors are specially highlighted. Beyond an assessment of the performances of the real-world application of these proposed optical sensors, the existing inadequacies and current challenges, as well as future perspectives for pesticide monitoring are discussed in detail. It is hoped to provide powerful insights for the development of novel CDs-based sensing strategies with their wide application in different fields for pesticide supervision.

Fungal communities in Nelumbinis semen characterized by high-throughput sequencing.

For a long period, Nelumbinis semen has been widely used as a medicinal and edible product. However, it is susceptible to contamination with toxigenic fungi and aflatoxins during the growth, collection, transportation, and storage processes, causing serious health threats to humans and huge economic losses. Effectively monitoring the fungal communities is of great importance to avoid aflatoxins contamination in Nelumbinis semen. High-throughput sequencing (HTS) is a new technology to evaluate fungal communities so as to overcome the limitations of the traditional cultural ways. In this study, the ITS2 based Illumina-MiSeq platform was developed to evaluate the fungal communities in normal and moldy Nelumbinis semen by using the HTS technology. Two different primer pairs were introduced to compare their performance in amplifying the target gene. The primer pair that produced more reads was selected to analyze the results. In all the nine tested Nelumbinis semen samples, 2 phyla, 5 classes, 6 orders, 8 families, 9 genera and 4 species were detected. A total of 9 genera were spotted, of which, Aspergillus (0.04%-72.93%) and Rhizopus (0.002%-48.12%) were the most dominant. ANOISM analysis showed no significant differences in the normal and moldy groups. The use of HTS technology can detect the fungal communities in complex Nelumbinis semen samples, providing an early warning for toxigenic fungi and aflatoxins contamination to warrant their quality and safety.

Development of a quantum dot nanobead-based fluorescent strip immunosensor for on-site detection of aflatoxin B1 in lotus seeds.

Owing to the serious threat of aflatoxin B1 (AFB1) to public health, development of a reliable method for accurate determination of it is extremely necessary and urgent. In this study, a simple, rapid and highly-sensitive quantum dot nanobeads (QBs) based lateral flow fluorescent strip immunosensor was developed for on-site detection of AFB1 in edible and medicinal lotus seeds. Carboxylated QBs were used as the fluorescent markers to prepare the fluorescent probe through coupling QBs with anti-AFB1 antibodies. Bovine serum albumin (BSA)-AFB1 antigens and goat anti-mouse IgG antibodies were coated on the nitrocellulose (NC) membrane to prepare the test (T) and control (C) lines, respectively. Qualitative analysis of AFB1 was realized by naked eye, and the quantitative determination was achieved with a portable strip reader. Results showed that the newly-developed test strip sensor could achieve rapid detection of AFB1 within 15 min, allowing a limit of detection (LOD) of 1 ng/mL (2 µg/kg) and a linear range of 1-19 ng/mL (2-38 µg/kg). Recovery rates from the fortified lotus seeds with low, medium and high spiking concentrations (2.5, 5 and 10 µg/kg) ranged from 94.0% to 116.0% with relative standard deviations less than 10%. All the results were confirmed by a standard LC-MS/MS method. The QBs-based fluorescent strip immunosensor with high sensitivity, easy operation, and low cost provided a preferred solution for rapid, on-site screening and highly-sensitive quantitation of AFB1 in a large number of lotus seed samples.

Development of a multi-channel magnetic bead micro-probe assay for high-throughput detection of zearalenone in edible and medicinal Coix seed.

A multi-channel magnetic bead micro-probes assay (MBPA) based on indirect competitive principle was developed for high-throughput detection of zearalenone (ZEA) in edible and medicinal Coix seed. This strategy introduced magnetic beads as the carriers, the specific primary antibodies as the capture probes for targets and the secondary antibodies functionalized goat anti-mouse immunoglobulin G labeled fluorescein isothiocyanate as the fluorescence signal probes. Through the competitive reaction of ZEA in Coix seed samples and that covalently coupled on the surface of MBs with their specific antibodies, as well as fast magnetic separation and sensitive fluorescence detection, the developed MBPA strategy allowed low limit of detection (2.03 ng/mL) with broad dynamic range (2.03-440.67 ng/mL), as well as excellent accuracy with the average recovery rate of 96.39% and relative standard deviation (RSD) of 5.48% for ZEA. 36 samples could realize simultaneous analysis in one operation within less than 20 min only needing 50 µL of solution and 30 s of sampling, avoiding large consumption of time and organic solvents. Multiple centrifugation and cleanup steps were omitted because of magnetic separation, avoiding the loss of targets. Diverse capture and fluorescent probes can be randomly bound onto the surface of MBs, making the MBPA strategy a promising tool for on-site high-throughput monitoring of various trace hazard factors in food safety, and environmental monitoring.

Butterfly Effects Arising from Starting Materials in Fused-Ring Electron Acceptors.

We designed and synthesized a series of fused-ring electron acceptors (FREAs) based on naphthalene-fused octacyclic cores end-capped by 3-(1,1-dicyanomethylene)-5,6-difluoro-1- indanone (NOICs) using a bottom-up approach. The NOIC series shares the same end groups and side chains, as well as similar fused-ring cores. The butterfly effects, arising from different methoxy positions in the starting materials, impact the design of the final FREAs, as well as their molecular packing, optical and electronic properties, charge transport, film morphology, and performance of organic solar cells. The binary-blend devices based on this NOIC series show power conversion efficiencies varying from 7.15% to 14.1%, due to the different intrinsic properties of the NOIC series, morphologies of blend films, and voltage losses of devices.

Recent progress in immunosensors for pesticides.

Immunosensors for rapid detection of pesticide residues has attracted considerable interest in the past few years for healthcare and environmental monitoring. And the publications have grown exponentially over the past decades, making it a trending hot-spot. Therefore, this review first examines the current situation regarding pesticide residue in various foods, feeds, traditional Chinese medicines and environmental samples. Then, the primary focus is on the recent development of the proposed immunosensors for pesticide detection in the past five years, with particular emphasis on the fluorescence, colorimetric, chemiluminescence, electrochemiluminescence, surface plasmon resonance, surface-enhanced Raman spectroscopy, electrochemical and piezoelectric sensors. Beyond a highlight of the real-world application and advantages of these emerging immunosensors for pesticide inspection, this paper also discusses their potential limits and current challenges, as well as future perspectives. This review will provide powerful insights to researchers for the future development of immunosensors, as well as their broader application in different fields, such as analytical chemistry, food safety control, clinical diagnostics, and environmental monitoring.

High-Efficiency Perovskite Quantum Dot Hybrid Nonfullerene Organic Solar Cells with Near-Zero Driving Force.

To take advantages of the intense absorption and fluorescence, high charge mobility, and high dielectric constant of CsPbI3 perovskite quantum dots (PQDs), PQD hybrid nonfullerene organic solar cells (OSCs) are fabricated. Addition of PQDs leads to simultaneous enhancement of open-circuit voltage (VOC ), short-circuit current density (JSC ), and fill factor (FF); power conversion efficiencies are boosted from 11.6% to 13.2% for PTB7-Th:FOIC blend and from 15.4% to 16.6% for PM6:Y6 blend. Incorporation of PQDs dramatically increases the energy of the charge transfer state, resulting in near-zero driving force and improved VOC . Interestingly, at near-zero driving force, the PQD hybrid OSCs show more efficient charge generation than the control device without PQDs, contributing to enhanced JSC , due to the formation of cascade band structure and increased molecular ordering. The strong fluorescence of the PQDs enhances the external quantum efficiency of the electroluminescence of the active layer, which can reduce nonradiative recombination voltage loss. The high dielectric constant of the PQDs screens the Coulombic interactions and reduces charge recombination, which is beneficial for increased FF. This work may open up wide applicability of perovskite quantum dots and an avenue toward high-performance nonfullerene solar cells.

Comparison of Fused-Ring Electron Acceptors with One- and Multidimensional Conformations.

Three fused-ring electron acceptors (FXIC-1, FXIC-2, and FXIC-3) were designed and synthesized. This FXIC series has similar electron-rich central units and the same electron-poor termini. Due to the different steric structures of fluorene, bifluorenylidene, and spirobifluorene, FXIC-1 is a one-dimensional (1D) crystal, while FXIC-2 and FXIC-3 are multidimensional (MD) amorphous materials. The conformations of the FXIC series have a slight impact on their absorption and energy levels. FXIC-1 has higher electron mobility than FXIC-2 and FXIC-3. When blending with different polymer donors (PTB7-Th, J71, and PM7), the FXIC-1-based organic solar cells have efficiencies higher than those of the FXIC-2/FXIC-3-based cells. Meanwhile, the ternary-blend cells based on PTB7-Th:F8IC with FXIC-1, FXIC-2, and FXIC-3 show similar efficiencies, which are all better than those of the binary-blend devices.

Highly Conjugated, Fused-Ring, Quadrupolar Organic Chromophores with Large Two-Photon Absorption Cross-Sections in the Near-Infrared.

The two-photon absorption (2PA) properties are investigated for two series of organic, π-conjugated, fused-ring, quadrupolar A-π-D-π-A chromophores of the type originally developed as nonfullerene acceptors for organic photovoltaics. These molecules are found to exhibit large nondegenerate two-photon absorption (ND2PA) cross-sections (ca. 6-27 × 103 GM) in the near-infrared (NIR). In the first series, involving molecules of varying core size, ND2PA spectra and cross-sections characterized by femtosecond ND2PA spectroscopy in chloroform solutions reveal that increases in core size, and thus conjugation length, leads to substantially red-shifted and enhanced 2PA. In a second series, variation of the strength of the terminal acceptor (A) with constant core size (seven rings, indacene-based) led to less dramatic variation in the 2PA properties. Among the two core types studied, compounds in which the donor has a thieno[3,2-b]thiophene center demonstrate larger 2PA cross-sections than their indacene-centered counterparts, due to the greater electron-richness of their cores amplifying intramolecular charge transfer. Excited-state absorption (ESA) contributions to nonlinear absorption measured by open-aperture Z-scans are deduced for some of the compounds by analyzing the spectral overlap between 2PA bands and NIR ESA transitions obtained by ND2PA and transient absorption measurements, respectively. ESA cross-sections extracted from transient absorption and irradiance-dependent open-aperture Z-scans are in reasonable agreement, and their moderate magnitudes (ca. 10-21 m2) suggest that, although ESA contributions are non-negligible, the effective response is predominantly instantaneous 2PA.

Development of a ZnCdS@ZnS quantum dots-based label-free electrochemiluminescence immunosensor for sensitive determination of aflatoxin B1 in lotus seed.

In this study, we designed a ZnCdS@ZnS quantum dots (QDs)-based label-free electrochemiluminescence (ECL) immunosensor for sensitive determination of aflatoxin B1 (AFB1). A Nafion solution assembled abundant QDs on the surface of a Au electrode as ECL signal probes, with specially coupled anti-AFB1 antibodies as the capturing element. As the reduction reaction between S2O82- in the electrolyte and QDs on the electrode led to ECL emission, the decreased ECL signals resulting from target AFB1 in the samples were recorded for quantification. We evaluated electrochemical impedance spectroscopy and ECL measurements along each step in the construction of the proposed immunosensor. After systematic optimization of crucial parameters, the ECL immunosensor exhibited a good sensitivity, with a low detection limit of 0.01 ng/mL for AFB1 in a wide concentration range of 0.05-100 ng/mL. Testing with lotus seed samples confirmed the satisfactory selectivity, stability, and reproducibility of the developed ECL immunosensor for rapid, efficient, and sensitive detection of AFB1 at trace levels in complex matrices. This study provides a powerful and universal analytical platform for a variety of analytes that can be used in broad applications for real-time analysis, such as food and traditional Chinese medicine safety testing, environmental pollution monitoring, and disease diagnostics. Graphical abstract Development of a ZnCdS@ZnS quantum dots based label-free electrochemiluminescence immunosensor for sensitive detection of aflatoxin B1 in lotus seed.

Enhancing Performance of Fused-Ring Electron Acceptor Using Pyrrole Instead of Thiophene.

Selecting suitable outermost aromatic rings of the central cores is of particular importance for the design of fused-ring electron acceptors (FREAs) because the direct electronic communication between the outermost aromatic rings and termini exerts a strong impact on the optoelectronic properties of FREAs. In most cases, the outermost rings of the FREA cores are thiophene. This work reported the first example of using pyrrole as the outermost rings of the core. Fused hexacyclic electron acceptor, P6IC, using pyrrole in place of the often-used thiophene as the outermost rings of the central core was synthesized. Compared with its structural analogue F6IC with thiophene as the outermost rings, P6IC exhibits a remarkably upshifted highest occupied molecular orbital energy level (P6IC: -5.43 eV, F6IC: -5.71 eV), a slightly upshifted lowest unoccupied molecular orbital energy level (P6IC: -3.94 eV, F6IC: -4.00 eV), 54 nm red-shifted absorption, a narrower band gap (P6IC: 1.30 eV, F6IC: 1.37 eV), and an enhanced mobility (P6IC: 8.8 × 10-4 cm2 V-1 s-1, F6IC: 7.4 × 10-4 cm2 V-1 s-1). Organic photovoltaic cells using PTB7-Th/P6IC as a photoactive layer exhibit an efficiency of 12.2%, far surpassing that based on PTB7-Th/F6IC active layer (5.57%). The semitransparent devices using PTB7-Th/P6IC as the active layer yield efficiency of 10.2% with an average visible transmittance (AVT) of 17.0%, far surpassing that based on PTB7-Th/F6IC (5.26% with an AVT of 18.4%).

Enhancing the Performance of a Fused-Ring Electron Acceptor by Unidirectional Extension.

The unidirectional extension of a smaller fused-ring system into a larger one in a single direction will increase the conjugation length, allowing a fine-tuning of electronic properties. Here, we designed and synthesized a unidirectionally extended fused-8-ring-based nonfullerene acceptor, AOIC, and a bidirectionally extended fused-11-ring electron acceptor, IUIC2, and compared these with the parent fused-5-ring electron acceptor, F5IC. They share the same electron-accepting groups and alkylphenyl side chains but have different fused-ring electron-donating units. Core extension from 5 to 11 rings up-shifts the energy levels, red shifts the absorption spectra, and reduces bandgaps. The unidirectionally extended AOIC has the highest mobility (2.1 × 10-3 cm2 V-1 s-1) relative to the parent F5IC (1.0 × 10-3 cm2 V-1 s-1) and the bidirectionally extended IUIC2 (4.7 × 10-4 cm2 V-1 s-1). Upon blending with the donor PTB7-Th, AOIC-based organic photovoltaic cells show an efficiency of 13.7%, much better than that of F5IC-based cells (5.61%) and IUIC2-based cells (4.48%).