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Search within results ((( Jean-Luc Brédas[Author]) AND 15[Journal]) AND year[Order]) AND OR NOT Title Author Institution Keyword Abstract PACS DOI Please wait a minute... For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails Select Band engineering in two-dimensional porphyrin- and phthalocyanine-based covalent organic frameworks: insight from molecular design Xiaojuan Ni, Jean-Luc Brédas Moore and More    2025, 1 (1): 26-39.   DOI: 10.1007/s44275-024-00007-y Abstract （6）      PDF（pc） （11882KB）（0）       Knowledge map    Save Two-dimensional covalent organic frameworks (2D COFs) represent an emerging class of crystalline polymeric networks, characterized by their tunable architectures and porosity, synthetic adaptability, and interesting optical, magnetic, and electrical properties. The incorporation of porphyrin (Por) or phthalocyanine (Pc) core units into 2D COFs provides an ideal platform for exploring the relationship between the COF geometric structure and its electronic properties in the case of tetragonal symmetry. In this work, on the basis of tight-binding models and density functional theory calculations, we describe the generic types of electronic band structures that can arise in tetragonal COFs. Three tetragonal lattice symmetries are examined: the basic square lattice, the Lieb lattice, and the checkerboard lattice. The potential topological characteristics of each lattice are explored. The Por-/Pc-based COFs exhibit characteristic band dispersions that are directly linked to their lattice symmetries and the nature of the frontier molecular orbitals of their building units. We show that the band dispersions in these COFs can be tailored by choosing specific symmetries of the molecular building units and/or by modulating the relative energies of the core and linker units. These strategies can be extended to a wide array of COFs, offering an effective approach to engineering their electronic properties. Reference | Related Articles | Metrics | Comments（0） Select Impact of the alkyl side-chain length on solubility, interchain packing, and charge-transport properties of amorphous π-conjugated polymers Qingqing Dai, Xingyou Lang, Jean-Luc Brédas, Tonghui Wang, Qing Jiang Moore and More    2025, 1 (1): 16-25.   DOI: 10.1007/s44275-024-00008-x Abstract （7）      PDF（pc） （2758KB）（0）       Knowledge map    Save Increasing the length of alkyl side chains is a typical way to improve the solubility of π-conjugated polymers designed for use in solution-processed devices. However, these modifications have also been reported to alter the film morphology. Given that the mechanism leading to improved solubility is not well documented yet and the nanoscale (local) morphologies of amorphous π-conjugated polymer films are difficult to characterize experimentally, here, we combine molecular dynamics simulations and long-range corrected density functional theory calculations to examine at the molecular scale the impact that the alkyl side-chain length has on polymer solubility and film morphologies. As a representative example, we consider poly(thieno[3,4-c]pyrrole-4,6-dione-alt-3,4-difluorothiophene) (PTPD[2F]T) with two different lengths of the alkyl side chains on the thieno[3,4-c]pyrrole-4,6-dione (TPD) moieties, i.e., 2-hexyldecyl (2HD) and 2-decyltetradecyl (2DT). A detailed analysis of polymer-solvent and polymer-polymer interactions provides a picture that describes the underlying mechanism for improved solubility in going from 2HD to 2DT. We then underline an intrinsic characteristic that decreasing the side-chain length brings a greater extent of backbone planarity and lesser side chain-TPD interactions, which leads to higher interchain π-π packing density and order, while the interchain π-π packing patterns remain similar in the two films. These morphologies are discussed in terms of the charge-transport properties between neighboring PTPD[2F]T chains, which point to a higher electron mobility in the PTPD[2F]T films with shorter alkyl side chains. Overall, our findings offer guidance in the field of solution-processed electronic devices by pointing out that the polymer alkyl side-chain length could be minimized to improve carrier mobility while ensuring polymer solubility. Reference | Related Articles | Metrics | Comments（0）