Friday, June 21, 2019

Abstract-Metal-Organic Framework Photoconductivity via Time-Resolved Terahertz Spectroscopy




Brian Pattengale, Jens Neu, Sarah Ostresh, Gongfang Hu, Jacob A Spies, Ryotaro Okabe, Gary W. Brudvig, Charles A. Schmuttenmaer

https://pubs.acs.org/doi/10.1021/jacs.9b04338

While metal-organic frameworks (MOFs) have been under thorough investigation over the past two decades, photoconductive MOFs are an emerging class of materials with promising applications in light harvesting and photocatalysis. To date, there is not a general method to investigate the photoconductivity of polycrystalline MOF samples as-prepared. Herein, we utilize time-resolved terahertz spectroscopy along with a new sample preparation method to determine the photoconductivity of Zn2TTFTB, an archetypical conductive MOF, in a non-contact manner. Using this technique, we were able to gain insight into MOF photoconductivity dynamics with sub-picosecond resolution, revealing two distinct carrier lifetimes of 0.6 ps and 31 ps and a long-lived component of several ns. Additionally, we determined the frequency dependent photoconductivity of Zn2TTFTB which was shown to follow Drude-Smith behavior. Such insights are crucially important with regard to developing the next generation of functional photoconductive MOF materials.

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