Boosting Photoelectric Conductivity in Porphyrin-Based MOFs Incorporating C₆₀

Journal Article · Thu Jan 23 00:00:00 EST 2020 · Journal of Physical Chemistry. C

DOI:https://doi.org/10.1021/acs.jpcc.9b10834· OSTI ID:1714366

Pratik, Saied Md  ^[1]; Gagliardi, Laura  ^[1]; Cramer, Christopher J.  ^[1]

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1. Univ. of Minnesota, Minneapolis, MN (United States). Minnesota Supercomputing Inst., and Chemical Theory Center

Electronic structure calculations show that guest C60 in the porphyrin-containing metal organic frameworks Zn₂(TCPB)(DA-ZnP) (DA-MOF; H₄TCPB = 1,2,4,5-tetrakis(4-carboxyphenyl)benzene, DA-ZnP = [5,15-bis[(4-pyridyl)ethynyl]-10,20-diphenylporphinato]zinc(II)) and Zn₂(TCPB)(F-ZnP) (F-MOF; F-ZnP = [5,15-di(4-pyridyl)-10,20-bis(pentafluorophenyl)porphinato]zinc(II)) engenders high photoelectrical conductivity due to efficient donor–acceptor charge-transfer (CT) interactions. Structural modifications at the meso position of the porphyrin influence the preferred positions of C₆₀ within the frameworks, giving rise to host–guest interactions with different anisotropic structural, electronic, and optoelectronic properties. A preferred slipped-parallel π-stacked interaction of C₆₀ that is predicted for NH₂-substituted DA-MOF and F-MOF fosters strong CT transitions and lowers band gaps by ~1.0 eV compared to the pristine DA-MOF and F-MOF. Hopping rates computed using Marcus theory are found to be anisotropic and accelerated by multiple orders of magnitude across π-stacked interfaces created by C₆₀ incorporation, a consequence of strong electronic coupling between initial and final diabatic states. Calculations indicate that photoinduced electron transfer, as well as direct CT from porphyrin to C₆₀ upon irradiation, triggers a charge separation process that leads to the formation of what should be long-lived electron-trapped states at the heterojunctions. Lastly, design principles revealed here for the control of photophysical and electron-transfer processes will be useful for constructing new MOF-derived visible- and infrared-based optoelectronics.

• Research Organization: Univ. of Minnesota, Minneapolis, MN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0008688; FG02-17ER16362
• OSTI ID: 1714366
• Journal Information: Journal of Physical Chemistry. C, Vol. 124, Issue 3; ISSN 1932-7447
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Charge transfer
Pyrroles
Metal organic frameworks
Chemical calculations
Electrical conductivity