Revealing Metal-Node-Dependent Intralayer Conjugation and Thickness-Dependent Interlayer Interactions in...

Area of Science:

• Materials Science
• Chemistry
• Physics

Background:

• Triphenylene (TP) based 2-dimensional (2D) metal-organic frameworks (MOFs) are promising for sensing, photo(electro)catalysis, energy storage, and optoelectronic applications.
• Understanding charge transport mechanisms in these materials is crucial for their application but remains poorly understood.

Purpose of the Study:

• To investigate the origins of charge transport behaviors in hexahydroxytriphenylene (HHTP) based MOFs.
• To identify strategies for tuning charge transport mechanisms in HHTP-based MOFs.

Main Methods:

• Utilized multiple spectroscopic techniques: steady-state X-ray absorption, UV-Visible-NIR absorption spectroscopy, and transient absorption spectroscopy.
• Employed first-principles calculations to complement experimental findings.
• Examined charge transport behaviors in hexahydroxytriphenylene (HHTP) based MOFs.

Main Results:

• The metal-to-ligand charge-transfer band is governed by the metal node identity, indicating the significance of metal-ligand d-π interactions.
• The near-infrared absorption band is strongly dependent on film thickness, suggesting the contribution of interlayer π-π interactions.
• Two distinct strategies for tuning charge transport mechanisms were identified.

Conclusions:

• Metal-ligand d-π interactions and interlayer π-π interactions are key factors governing charge transport in HHTP-based MOFs.
• Findings provide mechanistic insights for the rational design of HHTP-based MOFs for practical device applications.
• This research advances the understanding of charge transport in 2D MOFs for optoelectronic applications.