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The arrangement of organic semiconductor molecules in a material can be modulated using different supramolecular approaches, including the metal–organic framework (MOF) approach. These arrangements result in different frameworks topologies and structures. Fabrication of materials comprising optimized assemblies and functional molecules enables efficient tailoring of material properties, including electronic responses. Since semiconducting properties are sensitive to subtle changes in the nanostructure of the material, the exploitation of MOFs has promising potential in the development of new materials with designed structure and function. Based on decade-long method development, virtual design strategies have become ever more important, and such design methods profit from the availability of automated tools. Such tools enable screening of huge libraries of organic molecules in in silico models of the structure of three-dimensional nanoscale assemblies as the prerequisite to predict their functionality. In this report, we present and demonstrate the application of an automated workflow tool developed for MOFs of the primitive cubic (PCU) topology. We use pentacene-based ditopic linkers of a varied chemical composition and pillar linkers of different molecular sizes to automatically generate PCU MOFs, sample their structural dynamics at finite temperature, and predict electronic coupling matrix elements in vibrationally averaged assemblies. We demonstrate the change of the intermolecular ordering in the resulting MOFs and its impact on the semiconducting properties. This development lays the basis of an extendable framework to automatically model a wide variety of MOFs and characterize their function with respect to properties, such as conduction properties, absorption, and interaction with light. The developed workflow protocol and tools are available at https://github.com/KIT-Workflows/PCU-MOF.

In molecular solids, the intense photoluminescence (PL) observed for solvated dye molecules is often suppressed by nonradiative decay processes introduced by excitonic coupling to adjacent chromophores. We have developed a strategy to avoid this undesirable PL quenching by optimizing the chromophore packing. We integrated the photoactive compounds into metal-organic frameworks (MOFs) and tuned the molecular alignment by introducing adjustable “steric control units” (SCUs). We determined the optimal alignment of core-substituted naphthalenediimides (cNDIs) to yield highly emissive J-aggregates by a computational analysis. Then, we created a large library of handle-equipped MOF chromophoric linkers and computationally screened for the best SCUs. A thorough photophysical characterization confirmed the formation of J-aggregates with bright green emission, with unprecedented photoluminescent quantum yields for crystalline NDI-based materials. This data demonstrates the viability of MOF-based crystal engineering approaches that can be universally applied to tailor the photophysical properties of organic semiconductor materials., In molecular solids, photoluminescence of dye molecules is often suppressed owing to excitonic coupling with adjacent chromophores. Here the authors use a computational method to predict the optimal alignment of naphthalenediimide linkers in metal–organic frameworks to afford J-aggregates, and demonstrate the same by fabricating highly photoluminescent thin film.

An ideal material for photon harvesting must allow control of the exciton diffusion length and directionality. This is necessary in order to guide excitons to a reaction center, where their energy can drive a desired process. To reach this goal both of the following are required; short- and long-range structural order in the material and a detailed understanding of the excitonic transport. Here we present a strategy to realize crystalline chromophore assemblies with bespoke architecture. We demonstrate this approach by assembling anthracene dibenzoic acid chromophore into a highly anisotropic, crystalline structure using a layer-by-layer process. We observe two different types of photoexcited states; one monomer-related, the other excimer-related. By incorporating energy-accepting chromophores in this crystalline assembly at different positions, we demonstrate the highly anisotropic motion of the excimer-related state along the [010] direction of the chromophore assembly. In contrast, this anisotropic effect is inefficient for the monomer-related excited state., Exciton diffusion length and directionality are important parameters in artificial photosynthetic devices. Here, the authors present a way to make crystalline chromophore assemblies with bespoke architecture, fabricating one exhibiting anisotropic exciton transport properties.

An ideal material for photon harvesting must allow control of the exciton diffusion length and directionality. This is necessary in order to guide excitons to a reaction center, where their energy can drive a desired process. To reach this goal both of the following are required; short- and long-range structural order in the material and a detailed understanding of the excitonic transport. Here we present a strategy to realize crystalline chromophore assemblies with bespoke architecture. We demonstrate this approach by assembling anthracene dibenzoic acid chromophore into a highly anisotropic, crystalline structure using a layer-by-layer process. We observe two different types of photoexcited states; one monomer-related, the other excimer-related. By incorporating energy-accepting chromophores in this crystalline assembly at different positions, we demonstrate the highly anisotropic motion of the excimer-related state along the [010] direction of the chromophore assembly. In contrast, this anisotropic effect is inefficient for the monomer-related excited state.