Additive Mixing of Emissive Ligands in Covalent Organic Frameworks for White Light Emission
Not provided.
Materials Science↗
Engineering topics
Nyakuchena, James
Publications and source records attributed to Nyakuchena, James.
Manipulating Photoconduction in Cu–Pyrene 1-D Coordination Nanosheets by Modulating Interlayer π–π Stacking
2D conductive metal organic frameworks (MOFs) have become promising candidates for applications in electronic and photoelectronic devices. However, the lack of a fundamental understanding of the charge transport mechanism and synthetic design to alter their conductivity limits their potential applications. In this work, we report the design and synthesis of two 1D Cu–pyrene coordination nanosheets, Cu–pyrene-4,5,9,10 tetrathiol (Cu-PTT) and Cu–2,7-di-tert-butylpyrene-4,5,9,10-tetrathiol (Cu– tBu PTT), as models of 2D conductive MOFs, where the introduction of two different functional groups (H and tert-butyl groups) at the 2 and 7 positions of the PTT ligands is used to tune the interlayer distance and π–π stacking of MOFs. Using optical pump terahertz probe spectroscopy, we show that both nanosheets exhibit appreciable photoconduction, but the photoconduction in Cu– tBu PTT is reduced with respect to that in Cu–PTT, which can be attributed to the larger interlayer distance in the former leading to the decoupling of the interlayer charge transport pathway. Furthermore, these results demonstrate a unique strategy to investigate the impact of out-of-plane extended conjugation on photoconduction in conductive conjugated polymers, MOFs, or coordination nanosheets through adjusting their interlayer spacing.
14 SOLAR ENERGY↗
Dominant Role of Hole Transport Pathway in Achieving Record High Photoconductivity in Two‐Dimensional Metal–Organic Frameworks
Abstract Metal–organic frameworks (MOFs) with mobile charges have attracted significant attention due to their potential applications in photoelectric devices, chemical resistance sensors, and catalysis. However, fundamental understanding of the charge transport pathway within the framework and the key properties that determine the performance of conductive MOFs in photoelectric devices remain underexplored. Herein, we report the mechanisms of photoinduced charge transport and electron dynamics in the conductive 2D M−HHTP (M=Cu, Zn or Cu/Zn mixed; HHTP=2,3,6,7,10,11‐hexahydroxytriphenylene) MOFs and their correlation with photoconductivity using the combination of time‐resolved terahertz spectroscopy, optical transient absorption spectroscopy, X‐ray transient absorption spectroscopy, and density functional theory (DFT) calculations. We identify the through‐space hole transport mechanism through the interlayer sheet π–π interaction, where photoinduced hole state resides in HHTP ligand and electronic state is localized at the metal center. Moreover, the photoconductivity of the Cu−HHTP MOF is found to be 65.5 S m −1 , which represents the record high photoconductivity for porous MOF materials based on catecholate ligands.
Wang, Denan↗
Dominant Role of Hole Transport Pathway in Achieving Record High Photoconductivity in Two‐Dimensional Metal–Organic Frameworks
Abstract Metal–organic frameworks (MOFs) with mobile charges have attracted significant attention due to their potential applications in photoelectric devices, chemical resistance sensors, and catalysis. However, fundamental understanding of the charge transport pathway within the framework and the key properties that determine the performance of conductive MOFs in photoelectric devices remain underexplored. Herein, we report the mechanisms of photoinduced charge transport and electron dynamics in the conductive 2D M−HHTP (M=Cu, Zn or Cu/Zn mixed; HHTP=2,3,6,7,10,11‐hexahydroxytriphenylene) MOFs and their correlation with photoconductivity using the combination of time‐resolved terahertz spectroscopy, optical transient absorption spectroscopy, X‐ray transient absorption spectroscopy, and density functional theory (DFT) calculations. We identify the through‐space hole transport mechanism through the interlayer sheet π–π interaction, where photoinduced hole state resides in HHTP ligand and electronic state is localized at the metal center. Moreover, the photoconductivity of the Cu−HHTP MOF is found to be 65.5 S m −1 , which represents the record high photoconductivity for porous MOF materials based on catecholate ligands.
14 SOLAR ENERGY↗
Metal–Organic Framework as a Dual Support for Organic Photosensitizers and Single-Atom Catalysts
Metal–organic framework (MOF)-supported single-atom catalysts (SACs) possess integrated unique capabilities of both MOF and SACs, which represent a promising class of catalysts for photocatalytic applications. Herein, we report the incorporation of nickel (Ni) SACs onto its zirconium node and the functionalization of the organic linker of the zirconium MOF with perylene tetracarboxylic dianhydride (PDA), resulting in the formation of a hybrid MOF (denoted as Ni-PiU) with significantly enhanced light absorption ability in the visible region. Using the combination of time-resolved emission and X-ray absorption spectroscopy, we show that efficient charge separation occurs by electron transfer from incorporated PDA to Ni SACs with super slow charge recombination dynamics. As a result of these important photophysical properties, Ni-PiU MOF exhibits excellent photocatalytic activity and durability for the hydrogen evolution reaction. Finally, this work demonstrates the unique ability of MOFs as a dual platform to incorporate both SACs and a light absorption unit into their framework, providing a promising strategy for rational design of next-generation photocatalytic materials.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗