1. Air-water interface-assisted synthesis and charge transport characterization of quasi-2d polyacetylene films with enhanced electron mobility via ring-opening polymerization of pyrroleKejun Liu, Nadiia Pastukhova, Egon Pavlica, Gvido Bratina, Xinliang Feng, 2024, drugi sestavni deli Opis: Water surfaces catalyze some organic reactions more effectively, making them unique for 2D organic material synthesis. This report introduces a new synthesis method via surfactant-monolayer-assisted interfacial synthesis on water surfaces for ring-opening polymerization of pyrrole, producing distinct polypyrrole derivatives with polyacetylene backbones and ionic substitutions. The synthesis result in quasi 2D polyacetylene (q2DPA) film with enhanced charge transport behavior. We employed time-of-flight photoconductivity (TOFP) measurements using pulsed laser light of tunable wavelength for photoexcitation of the charge carriers within the q2DPA film. The charge transport was measured in the lateral direction as a function of external bias voltage ranging from 0 V to 200 V. We observed high electron mobility ({\mu}) of q2DPA reaching values of 375 cm2 V-1 s-1 at bias voltage Vb = -20V and photon energy of 3.8 eV.
Ključne besede: air-water interface-assisted synthesis, time-of-flight photoconductivity, 2D polymers, quasi 2D polyacetylene, q2DPA
Objavljeno v RUNG: 09.04.2024; Ogledov: 2889; Prenosov: 7
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2. High charge carrier mobility in thin films of quasi-two-dimensional polyacetylenes with sulphuric inter-chain linkersNadiia Pastukhova, Gvido Bratina, Egon Pavlica, 2023, objavljeni povzetek znanstvenega prispevka na konferenci Opis: Quasi-two-dimensional conjugated polymers (q2DCP) have been described and recognised as crystalline, one- or two-layer polymer nanosheets prepared by arranging linear conjugated polymer chains in a 2D plane via non-covalent interchain interactions.[1,2] The extension of polymer dimensionality to two dimensions improves the alignment of individual polymer layers and overcomes the limitations associated with charge carrier hopping between polymer chains in one-dimensional and crosslinked polymers [3] Compared to other two-dimensional materials such as graphene or transition metal dichalcogenides, q2DCPs offer a high degree of flexibility in chemical design and are compatible with liquid-based processing methods. Various q2DCPs have been synthesized by surface active monolayer-assisted interfacial synthesis (SMAIS) [5]
The photoreaction of these materials is of particular interest due to their tunable properties such as band gap and associated wavelength-dependent photoexcitation, which enables a wide range of applications in optoelectronic devices. Using time-of-flight photoconductivity measurements (TOF-PC) [4], we investigate the charge transport properties of 2D polyacetylene prepared by the SMAIS method. A typical TOFP measurement of q2D polyacetylene is shown in Figure 1, using a focused nanosecond pulse laser at 325 nm and an electrode spacing of 250 µm. From the polarity of the bias voltage and the duration of the photocurrent, we can determine the polarity, velocity, and mobility of the photo-excited carriers as a function of the applied bias voltage and excitation wavelength. and observed electron mobility of 250 cm2/Vs, which is in the range of the most advanced organic single-crystal small-molecule semiconductors and almost an order of magnitude higher than linear polymeric semiconductors. We investigated the optical absorption and transmission on a lateral scale using scanning near-field optical microscopy (SNOM).
Ključne besede: 2D polymers, organic semiconductors, q2DPA, SNOM, time-of-flight photoconductivity
Objavljeno v RUNG: 25.03.2024; Ogledov: 3265; Prenosov: 4
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6. Time-of-flight photoconductivity investigation of high charge carrier mobility in ▫$Ti_3C_2T_x$▫ MXenes thin-filmJurij Urbančič, Erika Tomsic, Manisha Chhikara, Nadiia Pastukhova, Vadym Tkachuk, Alex Dixon, Andraž Mavrič, Payam Hashemi, Davood Sabaghi, Ali Shaygan Nia, Gvido Bratina, Egon Pavlica, 2023, izvirni znanstveni članek Opis: Charge transport through a randomly oriented multilayered network of two-dimensional (2D) Ti3C2Tx (where Tx is the surface termination and corresponds to O, OH and F) was studied using time-of-flight photoconductivity (TOFP) method, which is highly sensitive to the distribution of charge carrier velocities. We prepared samples comprising Ti3C2Tx with thickness of 12 nm or 6-monolayers. MXene flakes of size up to 16 μm were randomly deposited on the surface by spin-coating from water solution. Using TOFP, we have measured electron mobility that reached values up to 279 cm2/Vs and increase with electric-field in a Poole-Frenkel manner. These values are approximately 50 times higher than previously reported field-effect mobility. Interestingly, our zero-electric-field extrapolate approaches electron mobility measured using terahertz absorption method, which represents intra-flake transport. Our data suggest that macroscopic charge transport is governed by two distinct mechanisms. The high mobility values are characteristic for the intra-flake charge transport via the manifold of delocalized states. On the other hand, the observed Poole-Frenkel dependence of charge carrier mobility on the electric field is typical for the disordered materials and suggest the existence of an important contribution of inter-flake hopping to the overall charge transport.
Ključne besede: charge transport, multilayered network, flakes, time-of-flight photoconductivity, MXene exfoliation, high-mobility solution-cast thin-film, semiconducting MXene
Objavljeno v RUNG: 31.03.2023; Ogledov: 3625; Prenosov: 30
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7. Nanoscopic roughness characterization of chitosan with buried graphene oxide for fuel cell applicationAhmed Kreta, Egon Pavlica, Mojca Božič, Gvido Bratina, 2023, objavljeni znanstveni prispevek na konferenci Ključne besede: AFM, chitosan, graphene oxide, fuel cells, membrane, roughness
Objavljeno v RUNG: 01.03.2023; Ogledov: 3725; Prenosov: 8
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8. Conjugated polymer mesocrystals with structural and optoelectronic coherence and anisotropy in three dimensionsLiyang Yu, Egon Pavlica, Ruipeng Li, Yufei Zhong, Carlos Silva, Gvido Bratina, Christian Műller, Aram Amassian, Natalie Stingelin, 2022, izvirni znanstveni članek Ključne besede: organic semiconductor, time-of-flight, charge carrier mobility, solid processing, large crystal
Objavljeno v RUNG: 28.02.2023; Ogledov: 2637; Prenosov: 84
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9. Solution-processed graphene-nanographene van der Waals heterostructures for photodetectors with efficient and ultralong charge separationZhaoyang Liu, Haixin Qiu, Shuai Fu, Can Wang, Xuelin Yao, Alex Dixon, Stéphane Campidelli, Egon Pavlica, Gvido Bratina, Sheng Zhao, Loïc Rondin, 2021, izvirni znanstveni članek Ključne besede: absorption, colloids, molecules, sensors, two dimensional materials
Objavljeno v RUNG: 28.02.2023; Ogledov: 2656; Prenosov: 0 |
10. Influence of P3HT:PCBM ratio on thermal and transport properties of bulk heterojunction solar cellsDorota Korte, Egon Pavlica, Domen Klančar, Gvido Bratina, Michal Pawlak, Ewa Gondek, Peng Song, Junyan Liu, Beata Derkowska-Zielińska, 2023, izvirni znanstveni članek Ključne besede: organic bulk-heterojunction solar cells, polymer-fullerene solar cells, photothermal beam deflection spectrometry, non-radiative recombination, thermal diffusivity, frequency domain methods
Objavljeno v RUNG: 09.01.2023; Ogledov: 3820; Prenosov: 24
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