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A few aspects of the nano‐morphology of hydrated Nafion and other ionomers and polyelectrolytes in their acid form are revisited by examining the evolution of small angle X‐ray scattering (SAXS) data which are recorded for a wide range of water volume fractions (Φwater ≈ 7–56 vol%). A consistency check with the recent “parallel cylinder model” discloses that this is most likely biased by a large uncertainty of the experimentally determined water content. We rather find our data to be consistent with locally flat and narrow (around 1 nm) water domains . The formation of relatively thin water “films” is suggested to be a common feature of many ionomers and polyelectrolytes, and the underlying driving force is most likely electrostatics within these highly dissociated systems. The water films may act as a charged (e.g., with positive protonic charge carriers) “glue”, keeping together the oppositely charged polymer structures. While this interaction tends to produce flat morphologies, the formation process is suggested to be constraint by limited conformational degrees of freedom of the corresponding polymer and the interactions between polymer backbones. This may leave severe tortuosities on larger scales which depend on the sample history (including swelling, de‐swelling, aging, stretching, and pressing). 相似文献
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Han Wang;Jacopo Pinna;David Garcia Romero;Lorenzo Di Mario;Razieh Mehrabi Koushki;Mordechai Kot;Giuseppe Portale;Maria Antonietta Loi; 《Advanced materials (Deerfield Beach, Fla.)》2024,36(19):2311526
The phase-transfer ligand exchange of PbS quantum dots (QDs) has substantially simplified device fabrication giving hope for future industrial exploitation. However, this technique when applied to QDs of large size (>4 nm) gives rise to inks with poor colloidal stability, thus hindering the development of QDs photodetectors in short-wavelength infrared range. Here, it is demonstrated that methylammonium lead iodide ligands can provide sufficient passivation of PbS QDs of size up to 6.7 nm, enabling inks with a minimum of ten-week shelf-life time, as proven by optical absorption and solution-small angle X-ray scattering. Furthermore, the maximum linear electron mobility of 4.7 × 10−2 cm2 V−1 s−1 is measured in field-effect transistors fabricated with fresh inks, while transistors fabricated with the same solution after ten-week storage retain 74% of the average starting electron mobility, demonstrating the outstanding quality both of the fresh and aged inks. Finally, photodetectors fabricated via blade-coating exhibit 76% external quantum efficiency at 1300 nm and 1.8 × 1012 Jones specific detectivity, values comparable with devices fabricated using ink with lower stability and wasteful methods such as spin-coating. 相似文献
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Guillaume Fleury Daniel Hermida‐Merino Dong Jingjin Karim Aissou Aleksei Bytchkov Giuseppe Portale 《Advanced functional materials》2019,29(10)
Spin coating is one of the most versatile methods to generate nanostructured block copolymer (BCP) thin films which are highly desired for many applications such as nanolithography or organic electronics. The self‐assembly pathways through phase separation, both in solvent and in bulk, strongly influence the final BCP structure obtained after spin coating. As a demonstration, the formation of highly ordered in‐plane lamellae is elucidated herein by using in situ grazing incidence small‐angle X‐ray scattering. A key step in this complex fast organization process is the formation of intermediate micellar phases triggered by solvent affinity toward one of the block. Indeed, directional coalescence of a short‐lived intermediate hexagonal structure of cylindrical micelles enables the development of a final highly ordered lamellar structure, predominantly oriented parallel to the substrate surface. These results suggest that the existence of such transient micellar phases is a crucial process in order to produce highly ordered structures with a specific orientation directly after the BCP thin film deposition; and should be the focus of further optimization for the directed self‐assembly and, more generally, in the bottom‐up nanostructure fabrication. 相似文献
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Jian Liu Li Qiu Riccardo Alessandri Xinkai Qiu Giuseppe Portale JingJin Dong Wytse Talsma Gang Ye Aprizal Akbar Sengrian Paulo C. T. Souza Maria Antonietta Loi Ryan C. Chiechi Siewert J. Marrink Jan C. Hummelen L. Jan Anton Koster 《Advanced materials (Deerfield Beach, Fla.)》2018,30(7)
In this contribution, for the first time, the molecular n‐doping of a donor–acceptor (D–A) copolymer achieving 200‐fold enhancement of electrical conductivity by rationally tailoring the side chains without changing its D–A backbone is successfully improved. Instead of the traditional alkyl side chains for poly{[N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl](NDI)‐alt‐5,5′‐(2,2′‐bithiophene)} (N2200), polar triethylene glycol type side chains is utilized and a high electrical conductivity of 0.17 S cm?1 after doping with (4‐(1,3‐dimethyl‐2,3‐dihydro‐1H‐benzoimidazol‐2‐yl)phenyl)dimethylamine is achieved, which is the highest reported value for n‐type D–A copolymers. Coarse‐grained molecular dynamics simulations indicate that the polar side chains can significantly reduce the clustering of dopant molecules and favor the dispersion of the dopant in the host matrix as compared to the traditional alkyl side chains. Accordingly, intimate contact between the host and dopant molecules in the NDI‐based copolymer with polar side chains facilitates molecular doping with increased doping efficiency and electrical conductivity. For the first time, a heterogeneous thermoelectric transport model for such a material is proposed, that is the percolation of charge carriers from conducting ordered regions through poorly conductive disordered regions, which provides pointers for further increase in the themoelectric properties of n‐type D–A copolymers. 相似文献
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Jun Xi Herman Duim Matteo Pitaro Kushagra Gahlot Jingjin Dong Giuseppe Portale Maria Antonietta Loi 《Advanced functional materials》2021,31(46):2105734
Low bandgap lead-tin halide perovskites are predicted to be candidates to maximize the performance of single junction and tandem solar cells based on metal halide perovskites. In spite of the tremendous progress in lab-scale device efficiency, devices fabricated with scalable techniques fail to reach the same efficiencies, which hinder their potential industrialization. Herein, a method is proposed that involves a template of a 2D perovskite deposited with a scalable technique (blade coating), which is then converted in situ to form a highly crystalline 3D lead-tin perovskite. These templated grown films are alloyed with stoichiometric ratio and are highly oriented with the (l00) planes aligning parallel to the substrate. The low surface/volume ratio of the obtained single-crystal-like films contributes to their enhanced stability in different environments. Finally, the converted films are demonstrated as active layer for solar cells, opening up the opportunity to develop this scalable technique for the growth of highly crystalline hybrid halide perovskites for photovoltaic devices. 相似文献
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Jingjin Dong Shuyan Shao Simon Kahmann Alexander J. Rommens Daniel Hermida‐Merino Gert H. ten Brink Maria A. Loi Giuseppe Portale 《Advanced functional materials》2020,30(24)
Knowledge of the mechanism of formation, orientation, and location of phases inside thin perovskite films is essential to optimize their optoelectronic properties. Among the most promising, low toxicity, lead‐free perovskites, the tin‐based ones are receiving much attention. Here, an extensive in situ and ex situ structural study is performed on the mechanism of crystallization from solution of 3D formamidinium tin iodide (FASnI3), 2D phenylethylammonium tin iodide (PEA2SnI4), and hybrid PEA2FAn?1SnnI3n+1 Ruddlesden–Popper perovskites. Addition of small amounts of low‐dimensional component promotes oriented 3D‐like crystallite growth in the top part of the film, together with an aligned quasi‐2D bottom‐rich phase. The sporadic bulk nucleation occurring in the pure 3D system is negligible in the pure 2D and in the hybrid systems with sufficiently high PEA content, where only surface crystallization occurs. Moreover, tin‐based perovskites form through a direct conversion of a disordered precursor phase without forming ordered solvated intermediates and thus without the need of thermal annealing steps. The findings are used to explain the device performances over a wide range of composition and shed light onto the mechanism of the formation of one of the most promising Sn‐based perovskites, providing opportunities to further improve the performances of these interesting Pb‐free materials. 相似文献
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Daniela Mileva Dario Cavallo Lorenza Gardella Giovanni C. Alfonso Giuseppe Portale Luigi Balzano René Androsch 《Polymer Bulletin》2011,67(3):497-510
The solidification of random isotactic copolymers of propylene and 1-butene has been followed in real time by wide-angle X-ray
scattering as a function of the rate of cooling the quiescent liquid. The experimental setup allowed simultaneous recording
of cooling curves—sample temperature as a function of time—and X-ray patterns at high sampling rate of 20 Hz. This approach
allowed establishing a correlation between cooling rate, temperature of crystallization/mesophase formation, and X-ray structure,
which formerly has only been observed ex situ, after completion of structure formation during cooling and subsequent aging.
It is quantitatively confirmed that addition of 1-butene co-units into the propylene chain allows mesophase formation on cooling
the melt at distinctly lower rate than in case of the homopolymer. The experimental results are compiled into a continuous
cooling transformation (CCT) diagram and compared with data obtained earlier on random copolymers of propylene with ethylene. 相似文献
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