The fluorination strategy has been proven effective in significantly enhancing the photovoltaic performance of organic solar cells (OSCs) based on non-fused ring electron acceptors (NFREAs). However, research on the impact of fluorination positions at side chains on NFREAs device performance remains scant. In this study, we introduce two isomeric NFREAs, designated as GA-2F-E and GA-2F, distinguished by their fluorination positions at the side chains. Both NFREAs share a thiophene[3,2-b]thiophene core, but their side chains differ: GA-2F-E f eatures two (4-butylphenyl)- N -(4-fluorophenyl) amino groups, whereas GA-2F's side chains consist of bis(4-fluorophenyl)amino and bis(4-butylphenyl)amino groups attached to opposite sides of the core. To delve into the influence of fluorination positions on the optoelectronic properties, aggregation behavior, and overall efficiency of the acceptor molecules, a comprehensive investigation was conducted. The findings reveal that, despite similar photophysical properties and comparable absorption bandwidths, GA-2F-E, with fluorine atoms positioned on both sides of the molecular framework, demonstrates more compact pi- pi stacking, reduced bimolecular recombination, superior exciton transport, and a more balanced, higher mobility. As a result of these advantages, OSCs optimized with D18:GA-2F-E achieve a remarkable power conversion efficiency (PCE) of 16.45 %, surpassing the 15.83 % PCE of devices utilizing D18:GA-2F. This research underscores the potential of NFREAs in future applications and highlights the significance of fluorination positions in enhancing OSC performance, paving the way for the development of more efficient NFREAs. (c) 2025 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

Cycloparaphenylenes (CPPs) have long been a focus of interest for their promising applications in materials science. Herein, we report the synthesis of electron-rich pyrene-embedded nanohoops, [2]OMe-Pyr-[8]CPP and [4]OMe-Pyr-[8]CPP. Single-crystal analysis revealed an oval-shaped cavity with a herringbone molecular packing arrangement, thereby facilitating the formation of extended tubular structures in both derivatives. Photophysical studies revealed that the two pyrene-embedded nanohoops exhibit nearly identical UV-vis absorption and fluorescence emission profiles. We further investigated the potential application of these nanohoops as dopants in organic solar cells (OSCs). When incorporated into D18:L8-BO-based OSCs, [2]OMe-Pyr-[8]CPP enhanced the power conversion efficiency (PCE) from 19.24% to 19.73%. Notably, [4]OMe-Pyr-[8]CPP delivered even better performance, achieving an impressive PCE of 19.96%. These observations indicate that the more electron-rich nanohoop demonstrated superior performance in the present case. These results highlight functionalized CPPs as promising materials for high-performance OSCs, providing an effective strategy for photovoltaic efficiency enhancement.

Designing the architecture of donor−acceptor (D−A) pairs is an effective strategy to tailor the electronic structure of conjugated macrocycles for optoelectronic devices. Herein, we present the synthesis of three D−A nanohoops NDI-[n]CPP (n=7, 8, 9) containing naphthalene diimide (NDI) unit as an acceptor and [n]cycloparaphenylenes ([n]CPPs) moieties as donors. The D−A characteristics of NDI-[7~9]CPPs were substantiated through absorption and fluorescence spectroscopic studies, electrochemical investigations and computational analysis. The device investigations demonstrated that the D-A nanohoops NDI-[7~9]CPPs can serve as the photoconductive layer and demonstrate a significant generation of photocurrent with fast response upon exposure to light. The magnitude of photocurrent shows highly dependence on the size of their rings, with an increasing trendency as the ring size decreases. The generation of photocurrent in free acceptor-based CPP has rarely been reported in the previous literatures. Significantly, the C60 complexes of NDI-[7~9]CPPs exhibited a marked enhancement in photocurrent under identical conditions, in particular, the photocurrent of C60NDI-[7]CPP is ca 3.5 times greater than that of NDI-[7]CPP alone. Furthermore, the potential applications of NDI-[7~9]CPPs in electron- and hole-transport devices have been also explored, revealing the clear evidence of their bipolar behavior as an active charge transport layer.

Compared to inorganic semiconductors, organic semiconductors (OSCs) exhibit lower permittivity and carrier mobility. This is primarily attributed to their weaker van der Waals forces and the significant structural and energetic disorder, ultimately impeding the commercial application of organic photovoltaics (OPVs). However, the introduction of n-type or p-type dopants offers a solution. These dopants effectively eliminate intrinsic traps in OSCs through trap-filling techniques, elevating carrier concentration and mobility, and consequently enhancing overall performance. This article delves into the systematic exploration of n-type and p-type dopant applications in OPVs. It encompasses doping mechanisms, commonly used n-type and p-type dopants, doping methodologies, the strategic distribution of dopants and the effect of doping on device performance. Ultimately, this concept strives to offer invaluable insights and guidance for advancing OPV performance via doping techniques.

A binary-mixed electron transport layer (ETL) has been reported for constructing solution-processable near-infrared organic light-emitting diodes (NIR OLEDs). Relative to the single-component ETL, the binary-mixed ETL composed of PDINN:TPBi can enhance the carrier transport capacity, reduce device impedance, and weaken fluorescence quenching of the emitting layer. By carefully selecting an appropriate luminescent material Y5 (a nonfullerene electron acceptor in organic solar cells) and precisely fine-tuning the molecular aggregation in active layer using a mixed solvent, the morphology is optimized and luminescence performance is enhanced, resulting in efficient NIR OLEDs with an emission peak at 890 nm. The experiment showcases a Y5-based near-infrared OLED with a maximum radiance of 34.9 W sr-1 m-2 and a maximum external quantum efficiency of 0.50%, which is among the highest values reported for non-doped fluorescent NIR OLEDs with an emission peak over 850 nm.

A nonfused ring electron acceptor (NFREA), designated as TT-Ph-C6, has been synthesized with the aim of enhancing the power conversion efficiency (PCE) of organic solar cells (OSCs). By integrating asymmetric phenylalkylamino side groups, TT-Ph-C6 demonstrates excellent solubility and its crystal structure exhibits compact packing structures with a three-dimensional molecular stacking network. These structural attributes markedly promote exciton diffusion and charge carrier mobility, particularly advantageous for the fabrication of thick-film devices. TT-Ph-C6-based devices have attained a PCE of 18.01% at a film thickness of 100 nm, and even at a film thickness of 300 nm, the PCE remains at 14.64%, surpassing that of devices based on 2BTh-2F. These remarkable properties position TT-Ph-C6 as a highly promising NFREA material for boosting the efficiency of OSCs.

Abstract Organic solar cells (OSCs) have emerged as one of the highly promising avenues in renewable energy due to their lightweight, flexible nature and the potential for low-cost manufacturing. This review provides a comprehensive overview about OSCs processed by halogen-free solvents. First, the state-of-the-art donor and acceptor materials are elaborated, and the design principles for efficient molecules are summarized. Second, the strategies for developing high-performance OSCs processed using nonhalogen solvents are investigated, including solvent engineering for solution pretreatment, thermal processing, and layer-by-layer techniques. Finally, prospects for future research directions are provided, highlighting the need for continuous innovation in nonhalogen solvent-processed OSCs, breaking through existing constraints, and driving the advancement of OSC technologies into the future.

Y-series nonfullerene acceptors (NFAs) usually bear halogenated end groups to achieve narrow bandgaps and tunable molecules crystallinity; however, it results in small open-circuit voltage (Voc) of 0.8-0.9 V. Here, three Y-series NFAs BTP-eC9-G51, BTP-eC9-G52, and BTP-eC9-G53 are synthesized by introducing both an electron-withdrawing fluoro group and electron-donating alkoxy group to commonly used 2-(3-oxo-2,3-dihydroinden1-ylidene)-malononitrile (IC) terminal groups. These compounds demonstrate a high Voc larger than 0.9 V when employed as acceptors in organic solar cells (0.91 V for BTP-eC9-G51 and 0.95 V for the others). The effect of alkoxy chain length of the molecules on the photoelectric properties is systematically studied. The results show that the dipole moments and aggregation behaviors of these molecules changes obviously with the increase of alkoxy chain length. The active layer based on BTP-eC9-G51 shows suitable phase separation structure and good charge transport. Devices based on BTP-eC9-G51 achieve a device efficiency of 16.65%, higher than those of BTP-eC9-G52 and BTP-eC9-G53 based devices (14.33% and 13.24%, respectively). Furthermore, BTP-eC9-G51 is introduced into D18:L8-BO devices as a third component, which improves the Jsc and Voc, reduces the nonradiation energy loss, and the device efficiency is increased to 19.03% with a high Voc of 0.92 V.

We designed and synthesized three chlorinated thiazole additives, namely TZ-Cl, TZ-2Cl and TZ-3Cl, which are characterized by an increasing number of chlorine atoms. Our research findings demonstrate the presence of supramolecular interactions between these additives and both polymer donors and non-fullerene acceptors. These interactions gradually intensify with an increasing number of chlorine atoms, thereby facilitating effective modulation of the crystallinity and aggregation states of the donor and acceptor molecules. Notably, the TZ-3Cl promotes a significantly refined dual-fibril interpenetrating network structure within the blend film. This enhanced active layer structure aids in extending exciton diffusion, improving exciton dissociation, and boosting charge transport, while simultaneously minimizing energy losses within the device. As a result, OSCs incorporating TZ-Cl, TZ-2Cl, and TZ-3Cl as additives in the PM6:L8-BO binary system achieved power conversion efficiencies (PCEs) of 18.3%, 18.5%, and 19.8%, respectively. Furthermore, in the PM6:BTP-eC9-4F:DM-F ternary OSC system, we attained a remarkable PCE of 20.2%. Overall, this study introduces a practical and innovative approach for designing high-efficiency OSC additives by leveraging supramolecular principles.

Electron transport layers (ETLs) are paramount important to enhance the performance in inverted perovskite solar cells (PSCs); however, modulation of the interfacial charge transfer (electron extraction) process at the perovskite/ETL interface is rarely achieved. In this study, a bilayer ETL was strategically designed to simultaneously improve electron extraction and optimize charge transport dynamics in inverted PSCs. Capitalizing on the strong electron extraction ability of C70 and the superior charge transport characteristics of C60, the bilayer ETL employs a functional stratification approach to regulate interfacial charge kinetics. An ultrathin C70 is positioned in direct contact with the perovskite active layer, significantly accelerates electron extraction and effectively passivates interfacial defects. The upper C60 layer, benefiting from its high electron mobility, establishes an efficient charge transport pathway while also suppressing hole back-injection. Comprehensive device characterization revealed that the PSCs incorporating this bilayer ETL exhibit enhanced device performance which achieved a PCE of 24.51%, being much larger than that of the control one (23.34% for C60 based device). Furthermore, the use of vacuum thermal evaporation ensures excellent film uniformity and reproducibility, providing a viable strategy for the industrialization of high-performance perovskite photovoltaic technologies.

To advance the commercialization of organic photovoltaics, there is an urgent demand for the development of high-performance wide-bandgap (WBG) polymer donors that simultaneously offer high efficiency and synthetic simplicity. In this study, we designed and synthesized three WBG donor polymers, namely PNDT-X (X 1/4 H/F/ Cl), based on naphthodithiophene unit dual-functionalized with ester and halogen groups. These polymers exhibit wide bandgaps of approximately 2.04 eV and deep highest occupied molecular orbital (HOMO) energy levels of around -5.45 eV, achieving excellent spectral complementarity with the L8-BO acceptor material. Notably, the chlorine-substituted PNDT-Cl polymer demonstrates enhanced pi-pi stacking and higher crystallinity, leading to an optimized fibrous morphology that significantly promotes exciton dissociation and charge transport. Consequently, organic solar cells (OSCs) based on PNDT-Cl:L8-BO achieve a power conversion efficiency (PCE) of 17.93 %, one of the superior ester-substituted donor polymer systems. Moreover, the corresponding semitransparent organic solar cell (ST-OSC) attains a PCE of 13.90 % without requiring complex optical engineering. Simultaneously, it maintains a high average visible transmittance (AVT) of 23.53 % and a competitive light utilization efficiency (LUE) of 3.27 %, successfully striking a balance between PCE and AVT. These research findings confirm that ester and halogen dual-functionalized naphthodithiophene serves as an ideal weak acceptor unit for constructing WBG donor polymers, holding great promise for the development of high-performance opaque and semitransparent OSCs with scalable production potential.

Developing functionalized cycloparaphenylenes (CPPs) that respond to various stimuli, particularly redox, remains challenging yet crucial for advanced nanocarbon applications. Here, we report the exploration of the synergy between the concave π‐extended tetrathiafulvalene (exTTF) and the curved CPP scaffold for constructing the rigid, conjugated nanohoop exTTF[10]CPP . X‐ray analysis reveals a unique spherical packing arrangement in which six adjacent nanohoops interlock through concave and convex interactions. Interestingly, fluorescence studies revealed that exTTF[10]CPP exhibited unexpected anti‐Kasha emissions originating from higher excited states, along with Kasha emission from S 1 excited state in toluene and THF. However, in a PMMA film, it displayed a redshifted Kasha emission. The unique Kasha/anti‐Kasha dual‐emission behavior represents a rarely explored photophysical phenomenon within exTTF derivatives and nanocarbon‐based systems. Ultraviolet‐Visible (UV–vis) absorption investigations showed that exTTF[10]CPP demonstrated reversible redox responsiveness with tunable binding affinity for C 60 up to 1.92 × 10 6 M −1 . Notably, femtosecond transient absorption measurements further revealed a prolonged lifetime of the charge‐separated state, C 60 •− /exTTF[10]CPP •+ , which provides sufficient time for charge utilization. This exceptional charge‐transfer property enhances the photocurrent in C 60 ⊂exTTF[10]CPP ‐based cast film, which is 2.43 times higher than that of exTTF[10]CPP alone, highlighting its potential in photoelectronic device.

Interlayer materials play a crucial role in achieving high efficiency in organic solar cells (OSCs). However, slight increases in film thickness often lead to significant charge accumulation and recombination, presenting a challenge for large-scale OSC device fabrication. Therefore, there is a pressing need for interlayer materials that are insensitive to variations in thickness. In this study, we synthesized a cost-effective cyano-modified perylene diimide (PDI) derivative, PDINBrCN, as an interlayer material. Compared to the analogous PDINBr, the introduction of cyano groups lowers the Lowest unoccupied molecular orbital (LUMO) energy level of the molecule, enhancing electron injection and charge transport efficiency. Additionally, PDINBrCN demonstrates excellent solubility in 2,2,2-trifluoroethanol (TFE) and effectively modifies the electrode work function, facilitating device fabrication through orthogonal solvent processing. When utilized as the cathode interlayer in D18:L8-BO devices, PDINBrCN achieved a high power conversion efficiency (PCE) of 18.83% with a film thickness of 10 nm. Importantly, PDINBrCN maintained a PCE of 17.90% even when the film thickness was increased to 50 nm. In contrast, the analogous PDI derivatives PDINBr and the star cathode interlayer material anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone (PDINN) achieved PCEs of 17.17% and 17.06%, respectively, at the same film thickness. Notably, PDINBrCN maintained a PCE of over 16% even with an interlayer thickness of 80 nm, marking one of the best results for small molecule PDI derivatives as cathode interlayer materials at this thickness. Our findings demonstrate that PDINBrCN exhibits excellent processability, electrode work function adjustment capability, and crucially, thickness-insensitive properties. Therefore, PDINBrCN holds promise as an efficient and cost-effective cathode interlayer material, with potential for future commercial applications in OSCs.

Near-infrared narrowband photodetectors (NPDs), renowned for their exceptional performance, are of great significance in applications spanning biosensing, health monitoring, and intelligent communication. In this research, we introduced a straightforward and versatile solution-processing approach for fabricating NPDs capable of near-infrared detection. This advancement is primarily driven by the integration of an independent organic optically selective layer (PM6:PTIC). Furthermore, we have incorporated a hybrid electron-blocking layer, composed of poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(4,4'-(N-(4butylphenyl)))] (TFB) and a cross-linkable small molecule, 4,4'-bis(3-vinyl-9H-carbazol-9-yl)1,1'-biphenyl (CBP-V), to facilitate selective carrier transport between the thin perovskite layer and the organic photoactive layer. By employing this strategy, we have successfully developed near-infrared NPDs with a responsivity of 0.49 A/W, a maximum external quantum efficiency reaching up to 72.41%, a full width at half-maximum (fwhm) of less than 100 nm, and an impressive specific detectivity of 6.74 × 1012 Jones. This innovative methodology not only alleviates the fabrication complexities associated with thick-film perovskites but also paves the way for the preparation of high-performance near-infrared NPDs. Additionally, these detectors show substantial promise in photoplethysmography (PPG) applications, enabling real-time, noninvasive heart rate monitoring with enhanced accuracy and reliability.

Organic solar cells(OSCs) with a vertically phase-separated active layer are crucial for achieving high power conversion efficiency(PCE). However, obtaining such morphology remains a significant challenge, particularly in thick-film devices. To address this challenge, we develop a blended solvent strategy aimed at regulating the downward penetration of acceptor molecules into the underlying donor layer in layer-by-layer(LBL) solution-processed OSCs. By combining a good solvent with a poor solvent and precisely adjusting the ratio of a fast-volatilizing good solvent(chloroform) to a slow-volatilizing poor solvent(o-xylene), we have finely tuned the spatial distribution of acceptor molecules in the active layer. This has successfully resulted in a vertically phase-separated structure and enhanced crystallinity of the acceptor phase, which is conducive to exciton diffusion, exciton dissociation, and charge transport. We have verified the existence of such morphology through film depthdependent light absorption spectroscopy and time-of-flight secondary ion mass spectrometry analysis. The PCE of D18/BTPe C9-4F-based OSCs prepared using this strategy has shown significant improvement, with the PCE of devices with a 100-nanometer-thick active layer increasing from 18.77% to 19.36%. Notably, when employing this strategy to prepare OSCs with a 300-nanometer-thick active layer, an impressive PCE value of 18.06% was achieved, marking it as the highest-performing thickfilm binary organic solar cell reported thus far.

In this study, two novel donor-acceptor (D-A) copolymers are designed and synthesized, DTBT-2T and DTBT-2T2F with 2,2 '-bithiophene or 3,3 '-difluoro-2,2 '-bithiophene as the donor unit and dithienobenzothiadiazole as the acceptor unit, and used them as donor materials in non-fullerene organic solar cells (OSCs). Due to enhanced planarity of polymer chains resulted by the intramolecular FS noncovalent interactions, the incorporation of 3,3 '-difluoro-2,2 '-bithiophene unit instead of 2,2 '-bithiophene into the polymers can enhance their molecular packing, crystallinity and hole mobility. The DTBT-2T:L8-BO based binary OSCs deliver a power conversion efficiency (PCE) of only 9.71% with a Voc of 0.78 V, a Jsc of 20.69 mA cm-2, and an FF of 59.67%. Moreover, the introduction of fluoro atoms can lower the highest occupied molecular orbital levels. As a result, DTBT-2T2F:L8-BO based single-junction binary OSCs exhibited less recombination loss, more balanced charge mobility, and more favorable morphology, resulting in an impressive PCE of 17.03% with a higher Voc of 0.89 V, a Jsc of 25.40 mA cm-2, and an FF of 75.74%. These results indicate that 3,3 '-difluoro-2,2 '-bithiophene unit can be used as an effective building block to synthesize high performance polymer donor materials. This work greatly expands the selection range of donor units for constructing high-performance polymers. A novel donor-acceptor (D-A) copolymer by incorporating 3,3 '-difluoro-2,2 '-bithiophene is synthesized. Introducing 3,3 '-difluoro-2,2 '-bithiophene unit introduces intramolecular FS noncovalent interactions, which can enhance the planarity of the polymer chain, thereby improve molecular packing, crystallinity, and hole mobility. Finally, a photoelectric conversion efficiency (PCE) of 17.03% is achieved. This work can provide a new strategy for the design and synthesis of polymer donor materials. image

This study successfully designed and synthesized two nonfused ring electron acceptors, 412-6F and 412-6Cl, modified with fluorine and chlorine substituents, respectively. Single-crystal analysis revealed that 412-6F possesses a planar molecular backbone and exhibits pronounced dipole-dipole interactions between the fluorine atoms on the lateral phenyl groups and the carbonyl oxygen atoms on the end groups. This specific interaction promotes dense end-group stacking, leading to a reduced interlayer spacing. Improved crystallinity and coherence length are observed in the D18 : 412-6F blend film. Conversely, 412-6Cl adopts a more distorted configuration and lacks these interactions. As a result, the organic solar cell (OSC) based on D18 : 412-6F achieved a remarkable power conversion efficiency of 18.03 %, surpassing the performance of the D18 : 412-6Cl OSC. This underscores the importance of designing novel acceptors with beneficial intermolecular interactions to enhance OSC efficiency, thus providing a new direction for organic photovoltaic advancement.

Layer-by-layer (LbL) deposition of active layers in organic solar cells (OSCs) offers immense potential for optimizing performance through precise tailoring of each layer. However, achieving high-performance LbL OSCs with distinct solid additives in each layer remains challenging. In this study, we explore a novel approach that strategically incorporates different solid additives into specific layers of LbL devices. To this end, we introduce FeCl 3 into the lower donor (D18) layer as a p-type dopant to enhance hole concentration and mobility. Concurrently, we incorporate the wide-band gap conjugated polymer poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) into the upper acceptor (L8-BO) layer to improve the morphology and prolong exciton lifetime. Unlike previous studies, our approach combines these two strategies to achieve higher and more balanced electron and hole mobility without affecting device open-circuit voltage, while also suppressing charge recombination. Consequently, the power conversion efficiency (PCE) of the D18+FeCl 3 /L8-BO device increases to 18.12 %, while the D18/L8-BO+PFO device attains a PCE of 18.79 %. These values represent substantial improvements over the control device′s PCE of 17.59 %. Notably, when both FeCl 3 and PFO are incorporated, the D18+FeCl 3 /L8-BO+PFO device achieves a remarkable PCE of 19.17 %. In summary, our research results demonstrate the effectiveness of the layered solid additive strategy in improving OSC performance.

The recovery of rare earth elements (REEs) from acidic wastewater is a crucial aspect of sustainable development, industrial processes, and human health. The remarkable success of current REE recovery methods notwithstanding, there is remains a compelling need to develop recovery technologies that exhibit favorable acid resistance, low production costs, convenient storage, high selectivity, recovery efficiency, and recyclability. To address these concerns, β-cyclodextrin-based nanosponges (β-CD@PVA-SA NSs) have been first time proposed as potential adsorbents for europium (Eu), dysprosium (Dy), and gadolinium (Gd) recovery. The nanosponges are synthesized by cross-linking β-cyclodextrin (β-CD) functionalized polyvinyl alcohol (PVA) and sodium alginate (SA). Experimental results indicate that β-CD@PVA-SA NSs exhibit remarkable selectivity for Eu, Dy, and Gd, with a maximum adsorption capacity of 222.22, 217.39, and 204.08 mg/g, respectively. The adsorption process conforms to the pseudo-second-order kinetic and Langmuir isothermal models. β-CD@PVA-SA NSs maintain exceptional selective adsorption effects towards RE ions that are present in simulated acidic mine drainage (AMD), thereby highlighting their potential for practical applications. β-CD@PVA-SA NSs are characterized by favorable stability and cyclicity, with an adsorption rate of roughly 94% even after undergoing six consecutive sorption-desorption tests. Furthermore, density functional theory (DFT) simulations have unveiled the fundamental interactions between the functional groups anchored in β-CD@PVA-SA NSs and the REEs, providing vital insights into their adsorption mechanism. β-CD@PVA-SA NSs are promising and environmentally friendly adsorbent material that features low cost, acid resistance, stable porous structure, good flexibility, portability, and recyclability. Their unique properties pave the way for water pollution remediation and rare earth resource recycling.