Periodic Reporting for period 1 - MS2DCOFO (Multiswtichable Two-dimensional Covalent Organic Framework-based Optoelectronics)
Berichtszeitraum: 2023-11-01 bis 2025-10-31
Organic field-effect transistors (OFETs) are crucial elements for the fabrication of flexible, wearable, and biocompatible electronic devices. As miniaturization is approaching its limits, bringing an end to Moore’s law, beyond−CMOS devices, “More-than-Moore” technologies aimed at functional diversification are emerging as a technologically viable strategy to boost data storage capacity in tomorrow’s digital electronics. Two-dimensional covalent organic frameworks (2D COFs) are tailored by covalently tethering suitably designed small organic units to form planar π-conjugated 2D networks. Since 2D COFs are constructed through the chemical tethering of different building blocks (cornerstones and linkers) via dynamic covalent organic chemistry approaches, they can be seen as ideal platforms to simultaneously incorporate different switchable units into a given 2D skeleton exhibiting a precise and robust structure. In this framework, the making of multi-responsive semiconducting 2D COFs represents a grand challenge, which can offer major technological advancement for the next generation of electronic devices. In the MS2DCOFO project, we have synthesized a novel photo-switchable 2D COF, and also developed unique methodology to synthesize 2D COF films with smooth bottom surface, which can be coated on MoS2 to achieve heterostructure-based semiconductors. The newly developed nanotechnology offers an alternative approach for fabricating multi-switchable semiconducting devices. The overall objectives of this project were to incorporate different stimuli responsive organic building blocks into highly crystalline 2D COFs, and further integrate the 2D COF films into semiconducting devices for complex logic operations. In summary, the MS2DCOFO project provides a guideline to design and synthesize photo-switchable 2D COFs, offers a new methodology for the fabrication of 2D COF-based semiconducting devices, and achieved 2D COF-based multi-responsive semiconductors for the first time. These new findings have the potential to bring technology revolution in the materials and electronic industry.
In the MS2DCOFO project, we have performed innovative research in the field of synthesizing 2D COF materials and hybrid optoelectronic devices based on heterostructures of switchable 2D COF systems and 2D transition-metal dichalcogenide (TMD) materials. Switchable 2D COF systems include two parts: a multi-switchable 2D COF synthesized from porphyrin and tetrathiafulvalene for photo-responsive and electrochemically responsive properties; a photo-switchable 2D COF constructed from an azobenzene-based building block. In the MS2DCOFO project, MoS2 was mainly chosen for fabricating heterostructures with the 2D COFs. The functional groups in the 2D COFs undergo a reversible switching process upon exposure to external stimuli, i.e. azobenzene groups switch between two (meta)stable states with different properties under UV/visible light irradiation, tuning the optoelectronic properties of the 2D COFs. By in-situ growth of the 2D COFs on Si/SiO2 substrates, which can be wet transferred onto MoS2 to construct heterostructure-based semiconducting devices for multi-responsive properties, including optical and electrochemical signals. The newly developed 2D COF materials and methodology for fabricating 2D logic devices provide guidance for the development of electronic and optoelectronic devices.
In addition to the above topics, we also developed an unprecedented zirconium-based MOF (PCN-999) possessing Zr6 and biformate-bridged (Zr6)2 clusters simultaneously, which exhibits an exceptional perfluorooctanoic acid (PFOA) uptake of 1089 mg/g (2.63 mmol/g), representing a ca. 50% increase over the previous record for MOFs. Single-crystal X-ray diffraction studies and computational analysis revealed that the (Zr6)2 clusters offer additional open coordination sites for hosting PFOA. The coordinated PFOAs further enhance the interaction between coordinated and free PFOAs for physical adsorption, boosting the adsorption capacity to an unparalleled high standard.
In addition to the above topics, we also developed an unprecedented zirconium-based MOF (PCN-999) possessing Zr6 and biformate-bridged (Zr6)2 clusters simultaneously, which exhibits an exceptional perfluorooctanoic acid (PFOA) uptake of 1089 mg/g (2.63 mmol/g), representing a ca. 50% increase over the previous record for MOFs. Single-crystal X-ray diffraction studies and computational analysis revealed that the (Zr6)2 clusters offer additional open coordination sites for hosting PFOA. The coordinated PFOAs further enhance the interaction between coordinated and free PFOAs for physical adsorption, boosting the adsorption capacity to an unparalleled high standard.
The MS2DCOFO project was focused on the development of switchable 2D COF materials and the methodology for fabricating 2D COF-based semiconductors, which can independently respond to external stimuli. Although some switchable 2D COFs have been reported, well-designable crystalline photo-switchable 2D COFs are rarely reported, and high-quality 2D COF films are difficult to obtain for semiconducting devices.
In the MS2DCOFO project: (1) a universal approach was explored to realize high-quality 2D COF films, in particular, 2D COF films can be fabricated under high temperature by this new methodology; (2) the bottom surface of the 2D COF film is controlled by the roughness of the SiO2 substrate (∼0.5 nm), which is important for the fabrication of 2D COF-based semiconducting devices; (3) for the first time, we achieved a 2D COF-based multi-responsive semiconducting device; (4) a new photo-switchable 2D COF (COF-TPA-Benzo-Azo) was achieved; (5) we developed a new MOF, which showed state-of-the-art performance for PFOA absorption.
In the MS2DCOFO project: (1) a universal approach was explored to realize high-quality 2D COF films, in particular, 2D COF films can be fabricated under high temperature by this new methodology; (2) the bottom surface of the 2D COF film is controlled by the roughness of the SiO2 substrate (∼0.5 nm), which is important for the fabrication of 2D COF-based semiconducting devices; (3) for the first time, we achieved a 2D COF-based multi-responsive semiconducting device; (4) a new photo-switchable 2D COF (COF-TPA-Benzo-Azo) was achieved; (5) we developed a new MOF, which showed state-of-the-art performance for PFOA absorption.