(Invited) Innovative MOF-Based Strategies for Assembling Chromophores: Perspectives for Next-Generation Organic Electronics
Authors: Woell Christof 
Published: August 2024

In the realm of organic electronics, such as photovoltaics, photodetectors, and light-emitting devices, the integration of organic chromophores into solid-state assemblies and their connection with electrodes is crucial. A notable development in this area is the use of metal-organic frameworks (MOFs), also referred to as the MOF method [1], which has been gaining traction. This approach involves using organic chromophores like anthracene and other planar aromatics, including Hexa-peri-hexabenzocoronene (HBC), equipped with coupling units, to create ditopic linkers that connect with metal-oxo nodes in MOFs. In view of the challenges of integrating MOF powders into devices, recent advancements have led to the development of layer-by-layer methods yielding high-quality, monolithic MOF thin films [2]. These films offer exceptional optical qualities and show, in many cases, a reduced density of defects.

MOFs' periodic structures enable the deliberate design of chromophore assemblies, impacting optical absorption through inter-molecular interactions. This design approach has facilitated the creation of structures like J-aggregates, initially simulated in silico and later realized experimentally [3]. Additionally, MOFs enable the realization of band-structure phenomena, such as indirect band gaps [4], and chiroptical effects, including circularly polarized light emission [5] and the helical sensitivity in photodetectors [6].

We've also explored lbl architectures for constructing heterostructures, useful in photon up-conversion applications. This involves leveraging MOFs' porous nature, as seen in the integration of C60 into SURMOF pores for applications like photoconductivity [7] and organic diodes [8]. Recent efforts have also focused on assembling non-centrosymmetric SURMOFs for nonlinear optical properties, demonstrating substantial second harmonic generation (SHG) activity [9].

Our presentation will showcase key instances of successfully incorporating organic chromophores into SURMOFs for device fabrication, emphasizing the synergy with theoretical models. Given the vast number (> 120,000) of known MOFs, a theoretical approach is essential to guide experimental efforts efficiently.

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