The reduced donor/acceptor interfacial area and relatively low electron mobility of fused ring electron acceptors confine charge carrier generation and transport in current sequential layer-by-layer(LbL) processed org...
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The reduced donor/acceptor interfacial area and relatively low electron mobility of fused ring electron acceptors confine charge carrier generation and transport in current sequential layer-by-layer(LbL) processed organic solar cells(OSCs), thus limiting the further improvement of power conversion efficiencies(PCEs). In view of the good compatibility and high electron mobility of fullerene, herein we develop a new fullerene derivative, FU-MO, and introduce it into the acceptor layer of LbL OSCs based on the D18/Y6 pair. FU-MO possesses good miscibility with the polymer donor, D18, and excellent electron mobility, which endows the D18/Y6+FU-MO blend film with shorter d-spacing, larger crystalline coherence length, improved crystal quality and optimized phase separation. Such enables D18/Y6+FU-MO based LbL devices to achieve reduced trap density, higher charge carrier mobilities, shrinkable extraction time and prolonged charge carrier lifetime, thus facilitating exciton dissociation and suppressing charge carrier recombination, compared with the pristine D18/Y6 counterparts. Therefore, D18/Y6+FU-MO based as-cast LbL OSCs gain a superior PCE of 19.44%, which is among the highest values for as-cast OSCs so far. This work demonstrates that introducing functional fullerene derivatives is an efficient route to boost PCEs of LbL OSCs.
Polythiophenes (PTs) are one of the most promising donor materials for organic solar cells (OSCs), because of their low-cost production. However, most PT-based OSCs suffer from inferior power conversion efficiencies (...
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Polythiophenes (PTs) are one of the most promising donor materials for organic solar cells (OSCs), because of their low-cost production. However, most PT-based OSCs suffer from inferior power conversion efficiencies (PCEs) currently, mainly due to the mismatched energy levels and hyper-miscibility of PTs with state-of-the-art fused ring electron acceptors (FREAs). On account of the issues, two ternary PT donors, PT-CN and PT-2CN, are developed by inserting the simple and strong electron-withdrawing units (3-cyanothiophene and 3,4-dicyanothiophene) into a low-cost PT, PTVT-T, via random copolymerization, respectively. Introducing the ternary unit not only deepens the highest occupied molecular orbital energy level and brings down the miscibility of PTs with FREAs, but also makes the crystallinity of the PTs first increase then decrease from PTVT-T, PT-CN to PT-2CN. Thus, the moderate miscibility and highest crystallinity of PT-CN endows the PT-CN:BTP-eC9 blend film with proper phase separation having orderly molecular stacking to achieve the most efficient exciton dissociation and lowest trap density. Such enables PT-CN:BTP-eC9 based devices to achieve the highest charge carrier mobilities and lifetime, suppressing charge carrier recombination and facilitating charge carrier extraction. Therefore, the PT-CN:BTP-eC9 based OSC affords a higher PCE of 17.27% than PTVT-T:BTP-eC9 and PT-2CN:BTP-eC9 based counterparts, which, to the best of our knowledge, is the highest value for PT-based OSCs so far. The results demonstrate that ternary copolymerization is a facile and efficient route to realize high-efficiency but low-cost PT donors. Two ternary polythiophenes (PTs), PT-CN and PT-2CN, as donors are developed to deepen energy levels, reduce miscibility and regulate crystallinity. PT-CN:BTP-eC9 based OSCs gain an impressive PCE of 17.27%, which is the record for PT-based OSCs.
The past three years have witnessed the power conversion efficiency (PCE) of organic solar cells (OSCs) rocketing to over 18%, due to outstanding advantages of non-fullerene acceptors (NFAs). However, large exciton bi...
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The past three years have witnessed the power conversion efficiency (PCE) of organic solar cells (OSCs) rocketing to over 18%, due to outstanding advantages of non-fullerene acceptors (NFAs). However, large exciton binding energy (E (b)) caused by strong Coulombic force is still one of the main limiting factors for high-performance OSCs. Thus, it is critical to reduce the E (b) for further enhancement of device performance. Many strategies have been developed to reduce the E (b) of organic materials previously. In this perspective, the calculation methods for E (b) and the relationship between E (b) and voltage loss (V (loss)) are discussed. Then, the effects of the properties of small-molecule acceptors on E (b) from the perspectives of fused-ring donor cores, end groups, side chains, and molecular packing are discussed. Finally, the potential directions for reducing E (b) and pointing out the trade-off between E (b) and bandgaps/miscibility are put forward. It is hoped that this perspective could provide a new thinking of a molecular design for the breakthrough of OSCs.
Heavy metals resulting from human activities pose significant threats to human health and the soil ecosystem. In the current study, 917 soil samples from Chongming Island in Shanghai, China, were examined for eight he...
Heavy metals resulting from human activities pose significant threats to human health and the soil ecosystem. In the current study, 917 soil samples from Chongming Island in Shanghai, China, were examined for eight heavy metals. The sources of contamination were identified by using a Positive Matrix Factorization (PMF) model. Meanwhile, spatial interpolation and Moran's I index were applied to validate the model in terms of spatial linkages. The results revealed that the average concentrations of As, Cd, Hg, Pb, Cr, Cu, Zn, and Ni in the soil were 8.87, 0.19, 0.06, 28.75, 76.01, 37.74, 88.93, and 30.33 mg kg(-1), respectively. The PMF analysis proved that heavy metals in the soil of the study area are mainly influenced by traffic sources (Cr and Pb), industrial sources (Zn, Cd, and Cu), station sources (Hg), and natural sources (As and Ni), with contribution rates of 22.23, 26.25, 36.38, and 15.14%, respectively. The combination of Moran's index and the spatial analysis method not only verified the analytical results of the receptor model on the one hand but also served as a supplementary explanation for the sources of heavy metals in the soil. The health risk assessment indicated that noncarcinogenic values were below the threshold values. The total carcinogenic risk (R-T) of different heavy metals has a descending order of Cr > As > Ni > Cd. The R-T values of multiple heavy metals for children and adults were 5.28 x 10(-04) and 4.10 x 10(-05), respectively, which were close to the risk threshold. Therefore, attention should be paid to the health risks, especially for children's skin contact, which is the main exposure pathway.
A three-axis fast tool servo (FTS) with a symmetric structure design to reduce the parasitic motion for realizing high tracking accuracy while maintaining high performances in stiffness and open-loop bandwidth is deve...
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A three-axis fast tool servo (FTS) with a symmetric structure design to reduce the parasitic motion for realizing high tracking accuracy while maintaining high performances in stiffness and open-loop bandwidth is developed for ultraprecision diamond cutting. Modeling, analysis, and optimization of performances by the finite-element method in six degree-of-freedom are conducted for designing the mechanism. Experiments are carried out to test the performances of the three-axis FTS, which show low parasitic motion, high tracking accuracy, and high dynamic response. With the low tracking error of close-loop control for each axis, complicated trajectory tracking in 3-D space is realized with a tracking error as small as 5 nm. Finally, complicated and irregular microstructures are fabricated by the three-axis FTS to demonstrate the practicability of the FTS.
The high trap density (generally 10(16) to 10(18) cm(-3)) in thin films of organic semiconductors is the primary reason for the inferior charge-carrier mobility and large nonradiative recombination energy loss (Delta ...
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The high trap density (generally 10(16) to 10(18) cm(-3)) in thin films of organic semiconductors is the primary reason for the inferior charge-carrier mobility and large nonradiative recombination energy loss (Delta E-nr) in organic solar cells (OSCs), limiting improvement in power conversion efficiencies (PCEs). In this study, the trap density in OSCs is efficiently reduced via extending the donor core of nonfullerene acceptors (NFAs) from a heptacyclic unit to a nonacyclic unit. TTPIC-4F with a nonacyclic unit has stronger intramolecular and intermolecular interactions, affording higher crystallinity in thin films relative to its counterpart BTPIC-4F. Thus, the D18:TTPIC-4F-based device achieves a lower trap density of 4.02 x 10(15) cm(-3), comparable to some typical high-performance inorganic/hybrid semiconductors, with higher mobility and inhibited charge-carrier recombination in devices. Therefore, the D18:TTPIC-4F-based OSC exhibits an impressive PCE of 17.1% with a low Delta E-nr of 0.208 eV, which is the best known value for A-D-A-type NFAs. Therefore, extending the donor core of NFAs is an efficient method for suppressing trap states in OSCs for high PCEs.
Controlling vertical phase separation of the active layer to enable efficient exciton dissociation and charge carrier transport is crucial to boost power conversion efficiencies (PCEs) of pseudoplanar heterojunction (...
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Controlling vertical phase separation of the active layer to enable efficient exciton dissociation and charge carrier transport is crucial to boost power conversion efficiencies (PCEs) of pseudoplanar heterojunction (PPHJ) organic solar cells (OSCs). However, how to optimize the vertical phase separation of PPHJ OSCs via molecule design is rarely reported yet. Herein, ternary polymerization strategy is employed to develop a series of polymer donors, DL1-DL4, and regulate their solubility, molecular aggregation, molecular orientation, and miscibility, thus efficiently manipulating vertical phase separation in PPHJ OSCs. Among them, DL1 not only has enhanced solubility, inhibited molecular aggregation and partial edge-on orientation to facilitate acceptor molecules, Y6, to permeate into polymer layer and increase donor/acceptor interfaces, but also sustains high crystallinity and appropriate miscibility with Y6 to acquire ordered molecular packing, thus achieving optimized vertical phase separation to well juggle exciton dissociation and charge transport in PPHJ devices. Therefore, DL1/Y6 based PPHJ OSCs gain the best exciton dissociation probability, highest charge carrier mobilities and weakest charge recombination, and thus afford an impressive PCE of 19.10%, which is the record value for terpolymer donors. It demonstrates that ternary polymerization is an efficient method to optimize vertical phase separation in PPHJ OSCs for high PCEs. Ternary polymerization strategy is employed to manipulate the vertical phase separation in pseudoplanar heterojunction (PPHJ) organic solar cells (OSCs). The terpolymer DL1, with enhanced solubility, partial edge-on orientation, and high crystallinity, endows DL1/Y6 PPHJ blend film with the optimized vertical phase separation. Therefore, DL1/Y6 based PPHJ OSCs afford an impressive PCE of 19.10%, which is the record for terpolymer ***
Solution processible organic solar cells (OSCs) have attracted much attention as one of the most promising candidates for sustainable energy techniques over the past two decades. So far, the power conversion efficienc...
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Solution processible organic solar cells (OSCs) have attracted much attention as one of the most promising candidates for sustainable energy techniques over the past two decades. So far, the power conversion efficiency (PCE) of OSCs has reached over 18% and increasingly closed the gap with inorganic and hybrid solar cells, which exceeds the requirement in efficiency towards commercial application. Low cost is generally labeled as one of the potential advantages of OSCs, compared with other photovoltaic technologies. However, currently most of the high-performance materials need tedious synthetic steps and/or suffer from relatively high cost. In addition, halogenated solvents which are highly toxic and expensive are widely used during processing;besides, they are not environmentally friendly, which would bring about extra expense for management and disposal. Thus, the development of low-cost high-performance materials, and cheap and "green" processing for OSCs is the imperative and urgent issue to be solved towards industrial-scale production. In this review, we summarize the recent advances in low-cost materials and eco-friendly processing for OSCs from the aspects of the synthetic method, photoactive materials, interfacial materials and processing solution. We hope that this review affords an overview and deep understanding of low-cost materials and processing solutions for OSCs. Finally, we will provide our perspectives on possible directions and challenges to further reduce the material cost of OSCs.
Transarterial radioembolization using radionuclide-labeled microspheres has shown efficacy in the treatment of hepatocellular carcinoma (HCC). In this study, a novel formulation of Polyvinyl alcohol-collagen microsphe...
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Transarterial radioembolization using radionuclide-labeled microspheres has shown efficacy in the treatment of hepatocellular carcinoma (HCC). In this study, a novel formulation of Polyvinyl alcohol-collagen microspheres (PCMs) with an optimal settling rate is developed. Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses confirm that the PCMs have uniform morphology with diameters ranging from 20 to 30 mu m. These microspheres are successfully labeled with I-131, exhibiting good in vitro stability. Subsequently, I-131-labeled PCMs are administered via the hepatic artery into rats with orthotopic HCC, leading to a significant increase in median overall survival (p < 0.05). Single photon emission computed tomography (SPECT/CT) imaging and immunohistochemical assessments demonstrate precise biodistribution and stable retention of I-131-PCMs in the liver for up to 14 days. Magnetic resonance imaging (MRI) further reveals the inhibition of tumor growth following I-131-PCM treatment. In summary, the I-131-PCMs display high radiolabeling efficiency, stability, and a promising radioembolization effect in the orthotopic HCC rodent model, highlighting their potential for use in interventional cancer therapy.
The limited exciton diffusion length (LD) of organic semiconductors constraints exciton dissociation in pseudo-planar heterojunction (PPHJ) organic solar cells (OSCs), which is deemed the bottleneck hampering the furt...
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The limited exciton diffusion length (LD) of organic semiconductors constraints exciton dissociation in pseudo-planar heterojunction (PPHJ) organic solar cells (OSCs), which is deemed the bottleneck hampering the further improvement in their power conversion efficiencies (PCEs). Herein, a solid-additive strategy was proposed to efficiently prolong the LD in PPHJ OSCs by developing a volatile solid additive, SA-5F, and blending it in non-fullerene acceptors. The addition of SA-5F endowed a Y6+ film with improved crystallinity and more compact molecular stacking, resulting in a higher photoluminescence quantum yield, larger overlap between its absorption and emission spectra, and shorter intermolecular distance compared with a pristine Y6 film. Thus, the Y6+ film achieved a higher exciton diffusion coefficient of 1.36 x 10-3 cm2 s-1 and, thus, similar to 24% improvement in the LD to 10.27 nm. The prolonged LD enabled D18/Y6+-based PPHJ devices to realize more efficient exciton dissociation and weaker charge recombination compared with their D18/Y6 counterparts. Therefore, D18/Y6+-based PPHJ OSCs afforded an impressive PCE of 19.11%, which is among the highest values reported to date. Moreover, this strategy exhibits excellent universality in improving the photovoltaic performance of different systems. Thus, it was demonstrated that introducing a solid additive is an efficient and universal strategy to prolong the LD in PPHJ OSCs and consequently boost their PCEs. A solid additive, SA-5F, is employed to promote molecular stacking, which leads to higher crystallinity, boosting the exciton diffusion coefficient and then exciton diffusion length. Thus, D18/Y6+-based PPHJ OSCs afford an impressive PCE of 19.11%.
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