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2. Time-of-flight photoconductivity investigation of high charge carrier mobility in Ti3C2Tx MXenes thin-filmJurij Urbančič, Erika Tomsič, Manisha Chhikara, Nadiia Pastukhova, Vadym Tkachuk, Andraž Mavrič, Gvido Bratina, Egon Pavlica, 2023, original scientific article Abstract: 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.
Keywords: Charge transport in multilayered network of flakes, Time-of-flight photoconductivity, MXene exfoliation, High-mobility solution-cast thin-film, Semiconducting mxene
Published in RUNG: 31.03.2023; Views: 446; Downloads: 0
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3. Nanoscopic Roughness Characterization of Chitosan with Buried Graphene Oxide for Fuel Cell ApplicationAhmed Kreta, Egon Pavlica, Mojca Božič, Gvido Bratina, 2023, published scientific conference contribution Keywords: AFM, chitosan, graphene oxide, fuel cells, membrane, roughness
Published in RUNG: 01.03.2023; Views: 635; Downloads: 0
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4. 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, original scientific article Keywords: organic semiconductor, time-of-flight, charge carrier mobility, solid processing, large crystal
Published in RUNG: 28.02.2023; Views: 470; Downloads: 80
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5. 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, original scientific article Keywords: absorption, colloids, molecules, sensors, two dimensional materials
Published in RUNG: 28.02.2023; Views: 509; Downloads: 0 |
6. Influence of P3HT:PCBM Ratio on Thermal and Transport Properties of Bulk Heterojunction Solar CellsDorota Korte, Egon Pavlica, Domen Klancar, Gvido Bratina, Michal Pawlak, Ewa Gondek, Peng Song, Junyan Liu, Beata Beata Derkowska-Zielinska, 2023, original scientific article Keywords: organic bulk-heterojunction solar cells, polymer-fullerene solar cells, photothermal beam
deflection spectrometry, non-radiative recombination, thermal diffusivity, frequency domain methods
Published in RUNG: 09.01.2023; Views: 690; Downloads: 14
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7. Photoexcited charge mobility in quasi two-dimensional polyacetyleneNadiia Pastukhova, Kejun Liu, Renhao Dong, Gvido Bratina, Xinliang Feng, Egon Pavlica, 2022, published scientific conference contribution abstract Abstract: Two-dimensional conjugated polymers (2DCPs) have been described and recognised as crystalline, one- to two-layer polymer nanosheets prepared by 2D covalent polymerization exhibiting strong in-plane π-electron delocalization with two orthogonal directions and weak out-of-plane π-π stacking.[1,2] The extension of polymer dimensionality into two dimensions improves the alignment of individual polymer sheets 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, 2DCPs offer a high degree of flexibility in chemical design and are compatible with liquid-based processing methods. Various 2DCPs have been synthesised by surfactant monolayer-assisted interfacial synthesis (SMAIS).[5]
Of particular interest is the photoresponse of these materials due to their tunable properties, such as bandgap and associated wavelength-dependent photoexcitation, which enables a wide range of applications in optoelectronic devices. Using time-of-flight photoconductivity (TOF-PC) measurements [4], we investigate the charge transport properties of 2D polyacetylene prepared by SMAIS method. We preform TOF-PC measurement of 2D polyacetylene using a focused nanosecond pulse laser at 325 nm and electrode separation of 250 µm. From the bias polarity and time duration of the photocurrent, we can determine the polarity, velocity and mobility of photoexcited charge carriers as a function of applied bias voltage and excitation wavelength. Using excitation at 325 m, we observed an electron mobility in the range of 150 cm2 V-1 s-1, which is in the realm of most advances small-molecule single-crystal organic semiconductors and almost an order of magnitude higher than linear polymeric semiconductors.
Keywords: Two-dimensional conjugated polymers, 2DCPs, 2Dpolymers, charge mobility, time-of-flight photoconductivity
Published in RUNG: 29.11.2022; Views: 540; Downloads: 0
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8. Enhancement of indacenodithiophene–benzothiadiazole copolymer field-effect mobility with MXenesJurij Urbančič, Nadiia Pastukhova, Manisha Chhikara, Hu Chen, Iain Mcculloch, Huanhuan Shi, Ali Shaygan Nia, Xinliang Feng, Egon Pavlica, Gvido Bratina, 2022, published scientific conference contribution abstract Abstract: The predominant mode of charge carrier transport in thin layers of organic semiconductors (OSs) is thermally-activated hopping between localized states. This results in lower charge mobility compared to inorganic semiconductors precluding the use of OSs in high-speed electronic devices. Therefore, significant effort is invested to improve charge carrier mobility of OS thin layers, which form the basis of most of the organic electronic devices. Recent advances in the field of two-dimensional (2D) materials stimulated their use as addition to OS thin layers to boost the charge carrier mobility. MXenes promise to deliver most of the benefits of 2D materials coupled with large scale fabrication capability. Herein we examined Ti3C2X (X is O or OH group termination) MXene, as a candidate to improve charge carrier mobility in thin layer of indacenodithiophene-co-benzothiadiazole (IDTBT), a polymer exhibiting high electron mobility in defect-free crystalline layers. In our work we demonstrate that improvement in electron mobility in solution-cast IDTBT thin layers can be achieved by depositing a non-connected network of MXene flakes at the gate-dielectric/IDBT interface. Bottom-gate field-effect transistors (FETs) comprising of Au electrodes on n-doped silicon wafer covered with 230 nm of thermally deposited SiO2 were prepared and characterized. Charge carrier mobilities determined from transfer characteristics of FETs composing neat IDTBT channels were found to be in the range of 1 - 2×10−2 cm2/Vs. Devices comprising MXene flakes at the interface between SiO2 and IDTBT, instead exhibited a factor of four increase in electron mobility, while preserving the on/off ratio of 104.
Keywords: MXene, IDTBT, charge carrier mobility, OFET
Published in RUNG: 20.10.2022; Views: 642; Downloads: 6
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9. Electrochemical ZnO-based impedimetric sensor for aqueous ammonia detection for precision animal agricultureKateryna Vyshniakova, Huiwen Bai, Victor Marco Rocha Malacco, Egon Pavlica, Richard M. Voyles, Shawn S. Donkin, Amanda Gehman, Robert A. Nawrocki, 2021, published scientific conference contribution abstract Keywords: electrochemical impedance spectroscopy, mixed conduction, organic sensor
Published in RUNG: 07.06.2021; Views: 1551; Downloads: 36
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10. Impedimetric detection of histamine using PEDOT:PSS-based organic electrochemical sensor for precision animal agricultureHuiwen Bai, Kateryna Vyshniakova, Egon Pavlica, Victor Marco Rocha Malacco, Alexandros Yiannikouris, Thirupathi Reddy Yerramreddy, Richard M. Voyles, Shawn S. Donkin, Robert A. Nawrocki, 2021, published scientific conference contribution abstract (invited lecture) Keywords: electrochemical impedance spectroscopy, mixed conduction
Published in RUNG: 07.06.2021; Views: 1488; Downloads: 36
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