Interplay of structural dynamics and electronic effects in an engineered assembly of pentacene in a metal���organic framework

Autor: Shu Seki, Ritesh Haldar, Bryce S. Richards, Shahriar Heidrich, Weiwei Xie, Farhad Ghalami, Jan Freudenberg, Marcus Elstner, Hongye Chen, Uwe H. F. Bunz, Christof Wöll, Ian A. Howard, Wolfgang Wenzel, Michael Ganschow, Mariana Kozlowska, Samrat Ghosh, Yusuke Tsutsui, Marius Jakoby
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Chemical Science
Chemical science, 12 (12), 4477–4483
ISSN: 2041-6520
2041-6539
DOI: 10.5445/ir/1000131261
Popis: Charge carrier mobility is an important figure of merit to evaluate organic semiconductor (OSC) materials. In aggregated OSCs, this quantity is determined by inter-chromophoric electronic and vibrational coupling. These key parameters sensitively depend on structural properties, including the density of defects. We have employed a new type of crystalline assembly strategy to engineer the arrangement of the OSC pentacene in a structure not realized as crystals to date. Our approach is based on metal–organic frameworks (MOFs), in which suitably substituted pentacenes act as ditopic linkers and assemble into highly ordered π-stacks with long-range order. Layer-by-layer fabrication of the MOF yields arrays of electronically coupled pentacene chains, running parallel to the substrate surface. Detailed photophysical studies reveal strong, anisotropic inter-pentacene electronic coupling, leading to efficient charge delocalization. Despite a high degree of structural order and pronounced dispersion of the 1D-bands for the static arrangement, our experimental results demonstrate hopping-like charge transport with an activation energy of 64 meV dominating the band transport over a wide range of temperatures. A thorough combined quantum mechanical and molecular dynamics investigation identifies frustrated localized rotations of the pentacene cores as the reason for the breakdown of band transport and paves the way for a crystal engineering strategy of molecular OSCs that independently varies the arrangement of the molecular cores and their vibrational degrees of freedom.
Pentacene assembled into 1D arrays using a metal–organic framework (MOF) approach. This cofacial packing motif, which is not present in pentacene bulk, shows an interesting interplay of band-like and hopping-type transport.
Databáze: OpenAIRE
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