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Different role of graphene for nonisothermal crystallization behavior of graphene filled poly(ether ether ketone) by different perparation methods
摘要： The nonisothermal crystallization investigation on different contents of graphene filled PEEK nanocomposites by ball milling and solution dispersed was performed on differential scanning calorimetry. Jeziorny and Mo's methods were selected to evaluate the result, so as to investigate the nonisothermal crystallization kinetics of pure PEEK and two kinds of PEEK/GE nanocomposites. Mo's method was demonstrated to be the most appropriate model to represent the crystallization behavior for neat PEEK and PEEK/GE nanocomposites under nonisothermal condition. The result showed that the absolute degree of crystallinity of both PEEK/GE nanocomposites decreased with increasing the content of graphene, but increased the nucleation activity for the nanocomposites. When the addition of graphene was 1 wt%, the dispersed method affected the crystallization mechanisms obviously, either promoting or hindering the polymer matrix crystallization. Overall, the method that filling graphene to PEEK matrix had influence on the nonisothermal crystallization process, hence affected the properties of nanocomposites.
关键词： dispersed methods,nonisothermal crystallization kinetics,nucleation activity,graphene,PEEK
更新于2025-09-23 15:19:57
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Interface Defects Passivation and Conductivity Improvement in Planar Perovskite Solar Cells Using Na2S Doped Compact-TiO2 Electron Transport Layers
摘要： Numerous trap states and low conductivity of compact TiO2 layers are major obstacles for achieving high power conversion efficiency and high stability perovskite solar cells. Here we report an effective Na2S doped TiO2 layer, which can improve the conductivity of TiO2 layers, the contact of TiO2/perovskite interface, and also the crystallinity of following perovskite layers. Comprehensive investigations demonstrate that Na cations would increase the conductivity of TiO2 layers while S anions would change the wettability of TiO2 layers, and improve the crystallinity of perovskite layers and passivate defects at the TiO2/PVK interface. Synergetic effects of dopants lead to a champion efficiency as high as 21.25% in unencapsulated PSCs, with much improved stability. Our work provides new insights on anion dopants in TiO2 layers which is usually neglected in previous reports, and also proposes a simple approach to produce low-cost and high-performance electron transporting layers for high performance PSCs.
关键词： electron extraction,additive,compact TiO2,perovskite solar cells,crystallization
更新于2025-09-23 15:19:57
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Kinetics of crystallization in 13.2Li2O-67.6SiO2-14.49Al2O3-3.3TiO2-0.4BaO-0.97ZnO glass ceramic powder: Part I: A model-free vs. model-fitting approach
摘要： Crystallization kinetics of lithium aluminosilicate glass powder has been investigated by model-free and model–fitting methods. Non-isothermal experiments were carried out using differential scanning calorimetry (DSC) to monitor crystallization behavior. Model-free activation energy has been calculated based on Ozawa-Flynn-wall (OFW), Kissinger-Akahira-Sunose (KAS) and Friedman (FR) methods during crystallization progress. Although activation energy does not significantly differ between the models (400 to 470 kJ/mol), partial Avrami coefficient n(α) varies considerably with rate and crystallization progress. A better description of the crystallization behavior could be observed by the comparison of model-free and model fitting methods. The conformity of one model has been approved with comparison of theoretical DSC curve and experimental results. Finally, a model which can more accurately describe the crystallization behavior of this material was suggested.
关键词： aluminosilicate,Kinetics,model-free,model-fitting,lithium,crystallization.
更新于2025-09-19 17:15:36
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Utilizing MVAD method to optimize crystallization and nanostructured surface of the perovskite film: Toward electroluminescent and ultraviolet photodetective bifunctional optoelectronics
摘要： Metal-halide perovskite of MAPbBr3, by exhibiting several remarkable optoproperties such as tunable energy bandgap, high absorption coefficients, high color purity, and long charge carrier diffusion lengths, has made great contributions to photovoltaic and electroluminescent (EL) technologies, i.e., solar cell, photodetector, light-emitting diode, and newly developed bifunctional optoelectronics. To realize high performance bifunctional optoelectronics, it is imperative to promote the balance of the trade-off between effective radiative recombination during EL process and fast exciton dissociation in photodetective process. Herein, we optimize the crystallization and nanostructured surface of MAPbBr3 film through applying multistep vapour assisted deposition (MVAD) method. Then, we enhance the optical field distribution and charge transfer feature of MAPbBr3 film by establishing an optical simulation model. Based on our modifed MAPbBr3 active layer, finally, we demonstrate a high performance device with EL and ultraviolet photodetective bifunctions, which exhbits a 6.27-fold improvement of brightness and a 3 orders of magnitude increase of detectivity. To the best of our knowledge, this work not only reports high bifunctional perovskite optoelectronics performance, but also illustrates the optical field redistribution process in horizontal orientation surface of MAPbBr3 films for relevant researchers.
关键词： Nanostructured surface,Perovskite film,Multistep vapour assisted deposition,Crystallization,Bifunctional optoelectronics
更新于2025-09-19 17:15:36
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Bioinspired Stable and Photoluminescent Assemblies for Power Generation
摘要： Peptide assemblies are ideal components for eco-friendly optoelectronic energy harvesting devices due to their intrinsic biocompatibility, ease of fabrication, and flexible functionalization. However, to date, their practical applications have been limited due to the difficulty in obtaining stable, high-performance devices. Here, it is shown that the tryptophan-based simplest peptide cyclo-glycine-tryptophan (cyclo-GW) forms mechanically robust (elastic modulus up to 24.0 GPa) and thermally stable up to 370 °C monoclinic crystals, due to a supramolecular packing combining dense parallel β-sheet hydrogen bonding and herringbone edge-to-face aromatic interactions. The directional and extensive driving forces further confer unique optical properties, including aggregation-induced blue emission and unusual stable photoluminescence. Moreover, the crystals produce a high and sustained open-circuit voltage (1.2 V) due to a high piezoelectric coefficient of 14.1 pC N?1. These findings demonstrate the feasibility of utilizing self-assembling peptides for fabrication of biointegrated microdevices that combine high structural stability, tailored optoelectronics, and significant energy harvesting properties.
关键词： photoluminescence,cyclo-dipeptides,crystallization,mechanics,piezoelectricity
更新于2025-09-19 17:15:36
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Confined versus Unconfined Crystallization in Block Copolymer/Salt Mixtures Studied by Depolarized Light Scattering
摘要： Crystallization in an ordered lamellar diblock copolymer/salt mixture, polystyrene-block-poly(ethylene oxide) mixed with lithium bis(trifluoromethanesulfonyl)imide salt (SEO/LiTFSI), has been studied using a combination of small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and depolarized light scattering (DPLS). Such materials have applications as electrolyte membranes in solid-state lithium batteries. The grain structure of the electrolyte was controlled by manipulating thermal history. Poly(ethylene oxide) (PEO) crystallization was confined within the microphase-separated morphology and did not affect the grain structure in the case of shallow quenches. Deep quenches resulted in unconfined crystallization, where crystal formation does not affect the microphase-separated morphology but does alter the grain structure. The difference between the two modes of crystallization can only be detected by DPLS. This knowledge is particularly relevant for nanostructured electrolytes wherein ion transport is a strong function of grain structure.
关键词： grain structure,block copolymer,crystallization,electrolyte,depolarized light scattering
更新于2025-09-19 17:15:36
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Optimizing the Phase-Separated Domain Size of the Active Layer via Sequential Crystallization in All-Polymer Solar Cells
摘要： Proper domain size of the active layer plays a key role in determining the exciton dissociation and charge transport in all polymer solar cells (all-PSCs). However, fine-tuning the domain size remains challenging due to low glass transition temperature and negligible mixing entropy in polymer blends. Herein, we systematically studied the influence of “crystallization kinetics” on the domain size and proposed that if donor and acceptor crystallize simultaneously, it is prone to form large domain size; while if sequential crystallization of donor and acceptor occurs, a fine phase separation structure with proper domain size can be obtained. Taking PBDB-T/PNDI blends for instance, the domain size was decreased by using sequential crystallization, meanwhile, the crystallinity and molecular orientation were optimized as well, boosting the power conversion efficiency (PCE) from 6.55% to 7.78%. This work provides a novel way to finely tune the heterojunction phase separation structures.
关键词： domain size,crystallization kinetics,sequential crystallization,all-polymer solar cells,phase separation
更新于2025-09-19 17:13:59
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Synergistic effect of additives on 2D perovskite film towards efficient and stable solar cell
摘要： Recently，two-dimensional (2D) organic-inorganic hybrid perovskites have attracted tremendous attention due to their excellent environment stability. However, the inhibition of out-of-plane charge transport limits the performance of 2D based perovskite solar cells (PVSCs). To overcome this issue, we prepare the vertical-orientated 2D perovskite film via introducing dimethyl sulfoxide (DMSO) and thio-semicarbazide (TSC) as additives into the precursor solution. High-quality 2D (BA)2(MA)3Pb4I13 (BA = n-butylammonium, MA = methylammonium) films with uniform morphology, increased grain size, intensified crystallinity and vertical orientation are therefore fabricated by a synergistic effect of additives. As a result, the trap-state density in 2D (BA)2(MA)3Pb4I13 films is reduced and the charge transport is remarkably improved. The power conversion efficiency (PCE) of the PVSCs is boosted from the 1.05% to 14.15%. An unsealed device retains 90.3% of its initial PCE after 720 h storage in air atmosphere with relative humidity of 25 ± 5% at 25 °C. The results show the synergistic effect of TSC and DMSO on perovskite films is an effective approach toward efficient and stable 2D PVSC.
关键词： stability,charge transport,orientation,synergistic effect,crystallization process,2D perovskite
更新于2025-09-19 17:13:59
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Minutea??Scale Rapid Crystallization of a Highly Dichroic 2D Hybrid Perovskite Crystal toward Efficient Polarizationa??Sensitive Photodetector
摘要： 2D hybrid perovskites demonstrate better performances than 3D counterparts in certain optoelectronic devices, whereas their natural attributes cannot be extracted from microcrystalline films, such as the natural dichroism for polarized light detection. Herein, for the first time, unusual minute-scale rapid crystallization is developed to grow bulk crystals of 2D hybrid perovskite, (FPEA)2PbI4 (1, FPEA is p-fluorophenethylammonium), which enables superior carrier transport property (≈64.1 ns) and low trap density (≈1010 cm?3). The rapid growth rate of 27.3 mm3 h?1 is almost two orders of magnitude higher than for other 2D counterparts. Strikingly, its natural quantum-confined motif results in extraordinary dichroism with optical absorption ratio αc/αa ≈ 2.05, revealing great promises for polarized light detection. Consequently, crystal-based photodetectors exhibit large photocurrent dichroic ratio Imax/Imin ≈ 2.1, fast response time (400 μs), and high detectivity (1011 Jones) to the polarized light. This is the record-fast crystallization of highly dichroic 2D hybrid perovskites, which opens a new prospect for their future optoelectronic device applications.
关键词： optical dichroism,rapid crystallization,polarized light detectors,hybrid perovskites
更新于2025-09-19 17:13:59
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Understanding the Morphology of High-performance Solar Cells Based on a Low Cost Polymer Donor
摘要： A low cost and high performance bulk heterojunction (BHJ) solar cell comprising an emerging polymer donor, poly[(thiophene)-alt-(6,7-difluoro-2-(2-hexyldecyloxy)quinoxaline)] (PTQ10), shows an efficiency of 12.7%. To improve performance of the solar cells, a better understanding of the structure-property relationships of the PTQ10-based devices is crucial. Here, we fabricate PTQ10/nonfullerene and fullerene BHJ devices, including PTQ10/IDIC, PTQ10/ITIC, and PTQ10/PC71BM, processed with or without thermal annealing and additive, provide detailed descriptions of the relationships between the morphology and performance. PTQ10 is found to be highly miscible with nonfullerene IDIC and ITIC acceptors, and poorly miscible with fullerene PC71BM acceptors. Thermal annealing promotes the crystallization of PTQ10 and phase separation of all PTQ10/IDIC, PTQ10/ITIC, and PTQ10/PC71BM devices, leading to an increased power conversion efficiencies (PCE) of the PTQ10/IDIC and PTQ10/ITIC devices but a decreased PCE of PTQ10/PC71BM devices with 1,8-di-iodooctane (DIO) additive. Without thermal annealing, DIO greatly improves the morphology of PTQ10/PC71BM, leading to a higher PCE. The results show that the degree of phase separation and ordering in the PTQ10-based devices significantly influence device performance. The morphology-property correlations demonstrated will assist in the rational design of this low cost polymer donor based solar cells to achieve even higher performance.
关键词： morphology,phase separation,polymer solar cells,miscibility,crystallization
更新于2025-09-19 17:13:59