Semitransparent organic photovoltaics (ST‐OPVs) have great potential for use in renewable energy technologies. In bulk‐heterojunction (BHJ) ST‐OPVs, a compromise is necessary between the visible ...light transmittance (VLT) and the power conversion efficiency (PCE). A sequential deposition (SD) strategy that involves individually depositing a polymer donor layer (D) and a small‐molecule acceptor layer (A) as the active layer is presented; where molecular diffusion occurring at the interfacial region results in a pseudo p–i–n structure. PBDB‐T‐2F(D)/Y6(A) ST‐OPVs are fabricated with different active layer thicknesses—at 115 nm, the SD (D:A/75:40 nm) and BHJ devices (D:A/1:1.2 w) provide the champion PCE of 12.91% (VLT of 14.5%) and 12.77% (VLT of 13.4%), respectively; at 85 nm, the SD (D:A/45:40 nm) and BHJ devices (D:A/1:1.2 w) provide a PCE of 12.22% (VLT of 22.2%) and 11.23% (VLT of 16.6%), respectively. This trend indicates SD devices have larger PCE and VLT values than the BHJ devices at a given active layer thickness, and the enhancements of PCE and VLT values by the SD structures against the BHJ structures become more pronounced as the active layer thickness reduced. The SD strategy provides a new approach for achieving ST‐OPVs with both high efficiency and high transparency.
In typical semitransparent organic photovoltaics (ST‐OPVs) that incorporate bulk heterojunction (BHJ) active layers, a compromise is made between the visible light transmittance (VLT) and power conversion efficiency (PCE). A new strategy with a sequential‐deposition (SD) active layer involving pseudo p–i–n structures provides ST‐OPVs with simultaneously higher PCE and VLT than that of the BHJ devices at the same layer thickness.
This study presents the synthesis of small-molecule acceptors having the structure A-D-A′-D-A-where A, A′, and D represent the end group, the core and π-bridge unit, respectively-that form the active ...layers with the polymer PM6 for organic photovoltaics. Increasing the number of core perylenetetracarboxylic diimide (PDI) units and conjugating them with thienothiophene (TT) or dithiophenepyrrole (DTP) π-bridge units enhanced the intramolecular charge transfer (ICT) and also increased effective conjugation, thereby, improving the light absorption and molecular packing. The absorption coefficient of hPDI-DTP-IC2F (two PDI with DTP) has the highest value (8 × 10
4
cm
−1
) because it featured the greatest degree of ICT, being much larger than that of PDI-TT-IC2F (one PDI with TT), hPDI-TT-IC2F (two PDI with TT) and PDI-DTP-IC2F (one PDI with DTP) (1.64 × 10
4
cm
−1
). The PM6:hPDI-DTP-IC2F device provided the highest power conversion efficiency (PCE) of 11.6%; this value was more than twice that of the PM6:PDI-DTP-IC2F (4.8%) device. This large increase in the PCE of the devices from the one-PDI core to two-PDI core case can be attributed to the two-PDI core case having (i) a stronger ICT, (ii) proper molecular packing that provided higher and more balanced carrier mobilities and (iii) a smaller energy loss than for the one-PDI case. Therefore, increasing the number of PDI units that were conjugated with suitable chromophores for stronger ICT in small molecule acceptors can be an effective way for enhancing the efficiency of organic photovoltaics.
This study presents the synthesis of small-molecule acceptors having the structure A-D-A′-D-A-where A, A′, and D represent the end group, the core and π-bridge unit, respectively-that form the active layers with the polymer PM6 for organic photovoltaics.
Thanks to the nature of molecular orbitals, the absorption spectra of organic semiconductors are not continuous like those in traditional inorganic semiconductors, which offers a unique application ...of organic photovoltaics (OPVs): semitransparent OPVs. Recently, the exciting progress of materials design has promoted the development of semitransparent OPVs. However, in the perspective of device engineering, almost all reported works reduce the thickness of back/reflected electrode to obtain high average visible transmittance (AVT), which is a trade‐off between power conversion efficiency (PCE) and the transmittance of the whole solar spectrum (visible and infrared), and therefore limit the further development. Herein, a unique strategy of “transparent hole‐transporting frameworks” is proposed. A hole‐transporting large‐bandgap polymer (polybis(4‐phenyl)(2,4,6‐trimethylphenyl)amine (PTAA)) is employed to partially replace polymer donors in the active layer of PBDB‐T/Y1. PTAA is a p‐type polymer with a large bandgap of 2.9 eV; the partial substitution of PBDB‐T by PTAA reduces the absorption of the active layer only in the visible region, keeping the hole‐transporting pathways as well as the optimized film morphology. As a result, semitransparent OPVs with PCEs of 12% and AVTs of 20% are achieved, both on rigid and flexible substrates. To demonstrate the generality, this strategy is also used in three different active layers.
A unique strategy of “transparent hole‐transporting frameworks” is proposed. A hole‐transporting large‐bandgap polymer, PTAA, is employed to partially replace the polymer donors in the active layer. As a result, semitransparent organic photovoltaic devices with power conversion efficiencies ≈12% and average visible transmittances ≈20% are achieved both on rigid and flexible substrates.
Marine corrosion and biofouling are the biggest challenges to the security of marine engineering equipment and offshore structures. Slippery liquid-infused porous surfaces (SLIPSs), emerging ...bio-inspired surfaces which have attracted widespread research interest over the past few years, have great potential in corrosion protection and biofouling prevention. It is valuable to summarize the most recent progress as well as to frame further opportunities in this field. In the current review, we have outlined the state-of-the-art fabrication strategies and applications of SLIPSs in anti-corrosion and anti-fouling coatings. Both lubricant-infused structured surfaces and oil-impregnated gels are discussed and compared in the fundamental section, and in the following sections their protection principles and performance in corrosion protection and biofouling prevention are presented separately. Finally, some critical unsolved challenges, as well as the research foci in the future, are proposed in the perspective section.
Slippery liquid-infused porous surfaces, emerging bio-inspired surfaces which have attracted widespread research interest over the past few years, have great potential in both corrosion protection and biofouling prevention.
This paper reports two new fluorine-substituted polymer donors (BO2FC8, BO2FEH), with different side-chain architectures, and a new chlorine-substituted small-molecule acceptor ( m -ITIC-OR-4Cl) that ...are capable of simultaneous charge and energy transfer as the binary blend active layer for organic photovoltaics. We first resolved the single-crystal structure of m -ITIC-OR-4Cl and then used simultaneous grazing-incidence wide- and small-angle X-ray scattering to decipher the multi-length-scale structures—such as the shape and size of aggregated domains and molecular orientation—of the blends of BO2FEH and BO2FC8 with m -ITIC-OR-4Cl. The linear side chains of BO2FC8 facilitated its packing and, thus, induced m -ITIC-OR-4Cl to form smaller disc-shaped aggregated domains (thickness: 2.9 nm) than its aggregate domain (thickness: 5.4 nm) in the blend of the branched BO2FEH. That is, the binary blend system of linear-side-chain BO2FC8 with m -ITIC-OR-4Cl featured larger interfacial areas and more pathways for charge transfer and transport, as evidenced by their carrier mobilities. The highest power conversion efficiency (PCE) of 11.0% was that for the BO2FC8: m -ITIC-OR-4Cl device, being consistent with the predicted PCE of 11.2% using machine learning based on random forest algorism; in comparison, the PCE of the BO2FEH: m -ITIC-OR-4Cl device was 6.4%. This study has not only provided insight into the photovoltaic performances of new polymer donor/small-molecule acceptor blends but has also, for the first time, deciphered the hierarchical morphologies—from molecule orientation to nano-domain shape and size—of such blend systems, linking the morphologies to the photovoltaic performances. The use of side-chain architectures suggests an approach for tuning the morphology of the polymer/small-molecule binary blend active layer for use in organic photovoltaics.
Lead zirconate titanate (PZT)‐based piezoelectric ceramics are important functional materials for various electromechanical applications, including sensors, actuators, and transducers. High ...piezoelectric coefficient and mechanical quality factor are essential for the resonant piezoelectric application. However, since these properties are often inversely proportional, simultaneously high performances are hard to achieve, consequently, a wide range of applications are strongly restricted. In the present study, exceptionally well‐balanced performances are achieved in PZT‐based ceramics via innovative defect engineering, which involves multi‐scale coordination among defect dipole, domain‐wall density, and grain boundary. These materials are superior to many state‐of‐the‐art commercial counterparts, which can potentially satisfy high‐end requirements for advanced electromechanical applications, such as energy harvesting, structural health monitoring, robotic sensors, and actuator.
Exceptionally well‐balanced piezoelectric performances are achieved in (Pb0.92Sr0.08)(Zr0.533Ti0.443Nb0.024)O3‐xwt%Mn (abbreviated as PSZTN‐Mn) ferroelectric ceramics (d33 = 510–460 pC N−1, Qm = 614–750), which is superior to many state‐of‐the‐art commercial piezoelectric ceramics. The high performance is proposed to originate from multi‐sale coordination among defect dipoles, domain wall, and grain boundary.
Abstract
Solar‐driven evaporation process brings exciting opportunities to recover clean water and resources in a sustainable way from diverse sources like seawater and wastewater. Separation ...membranes, as a vital material in many environmental and energy applications, can contribute significantly to this process owing to their structural features. However, the unique roles of membranes in solar evaporator construction and process design are seldom recognized and not summarized yet from scientific principles and application demands, which forms the motivation of this review. Herein, the roles of membranes in different processes based on solar‐driven evaporation are focused and the design principles of membrane materials and devices to meet the requirements of these applications are discussed. Fabrication strategies for photothermal membranes are introduced primarily, followed by a discussion on how to design membrane materials, devices, and processes to pursue optimal performance and realize advanced functions accompanied by evaporation. Furthermore, the future of this field is forecast with both challenges and opportunities.
Defect engineering is a well‐established approach to customize the functionalities of perovskite oxides. In demanding high‐power applications of piezoelectric materials, acceptor doping serves as the ...state‐of‐the‐art hardening approach, but inevitably deteriorates the electromechanical properties. Here, a new hardening effect associated with isolated oxygen vacancies for achieving well‐balanced performances is proposed. Guided by theoretical design, a well‐balanced performance of mechanical quality factor (Qm) and piezoelectric coefficient (d33) is achieved in lead‐free potassium sodium niobate ceramics, where Qm increases by over 60% while d33 remains almost unchanged. By atomic‐scale Z‐contrast imaging, hysteresis measurement, and quantitative piezoresponse force microscopy analysis, it is revealed that the improved Qm results from the inhibition of both extrinsic and intrinsic losses while the unchanged d33 is associated with the polarization contributions being retained. More encouragingly, the hardening effect shows exceptional stability with increasing vibration velocity, offering potential in material design for practical high‐power applications such as pharmaceutical extraction and ultrasonic osteotomes.
A novel strategy is developed for the hardening of piezoelectrics via the mediation of dopant‐exclusive oxygen vacancies to overcome the long‐term issue: the dilemma between the mechanical quality factor and piezoelectricity coefficient. The approach also makes the high‐power performance superior to many state‐of‐the‐art counterparts, offering a possible route to various piezoelectrics for high‐end applications.
Understanding the role of the oxidation state of the Cu surface and surface-adsorbed intermediate species in electrochemical CO2 reduction is crucial for the development of selective CO2-to-fuel ...electrocatalysts. In this study, the electrochemical CO2 reduction mechanism over the Cu catalysts with various oxidation states was studied by using in situ surface-enhanced infrared absorption spectroscopy (SEIRAS), in situ soft X-ray absorption spectroscopy (Cu L-edge), and online gas chromatography measurements. The atop-adsorbed CO (COatop) intermediate is obtained on the electrodeposited Cu surface which primarily has the oxidation state of Cu(I). COatop is further reduced, followed by the formation of C1 product such as CH4. The residual bridge-adsorbed CO (CObridge) is formed on the as-prepared Cu surface with Cu(0) which inhibits hydrocarbon formation. In contrast, the CV-treated Cu electrode prepared by oxidizing the as-prepared Cu surface contains different amounts of Cu(I) and Cu(0) states. The major theme of this work is that in situ SEIRAS results show the coexistence of COatop and CObridge as the reaction intermediates during CO2 reduction and that the selectivity of CO2-to-ethylene conversion is further enhanced in the CV-treated Cu electrode. The Cu catalysts modulated by the electrochemical method exhibit different oxidation states and reaction intermediates as well as electrocatalytic properties.
Hepatocellular carcinoma (HCC) is a highly heterogeneous disease, which makes the prognostic prediction challenging. Ferroptosis, an iron-dependent form of regulated cell death, can be induced by ...sorafenib. However, the prognostic value of ferroptosis-related genes in HCC remains to be further elucidated. In this study, the mRNA expression profiles and corresponding clinical data of HCC patients were downloaded from public databases. The least absolute shrinkage and selection operator (LASSO) Cox regression model was utilized to construct a multigene signature in the TCGA cohort. HCC patients from the ICGC cohort were used for validation. Our results showed that most of the ferroptosis-related genes (81.7%) were differentially expressed between HCC and adjacent normal tissues in the TCGA cohort. Twenty-six differentially expressed genes (DEGs) were correlated with overall survival (OS) in the univariate Cox regression analysis (all adjusted
< 0.05). A 10-gene signature was constructed to stratify patients into two risk groups. Patients in the high-risk group showed significantly reduced OS compared with patients in the low-risk group (
< 0.001 in the TCGA cohort and
= 0.001 in the ICGC cohort). The risk score was an independent predictor for OS in multivariate Cox regression analyses (HR> 1,
< 0.01). Receiver operating characteristic (ROC) curve analysis confirmed the signature's predictive capacity. Functional analysis revealed that immune-related pathways were enriched, and immune status were different between two risk groups. In conclusion, a novel ferroptosis-related gene signature can be used for prognostic prediction in HCC. Targeting ferroptosis may be a therapeutic alternative for HCC.
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