Photoexcited charge mobility in quasi two-dimensional polyacetylene
Nadiia Pastukhova a, Kejun Liu b, Renhao Dong b, Gvido Bratina a, Xinliang Feng b, Egon Pavlica a
a Laboratory of Organic Matter Physics, University of Nova Gorica, Slovenia, Vipavska cesta, Slovenia
b Chair for Molecular Functional Materials, Center for Advancing Electronics Dresden, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Germany, 01069 Dresde, Alemania, Dresde, Germany
Proceedings of Organic 2D Crystalline Materials: Chemistry, Physics and Devices (O2DMAT)
Madrid, Spain, 2022 September 15th - 16th
Organizers: Enrique Cánovas, Renhao Dong and Hai Wang
Contributed talk, Nadiia Pastukhova, presentation 005
Publication date: 11th July 2022

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 cmV-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.

The work was supported in part by the Slovenian Research Agency (Project No. Z1-3189).

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