jz9b03383_si_001.pdf (2.61 MB)
Broad-Band Near-Infrared Doublet Emission in a Tetrathiafulvalene-Based Metal–Organic Framework
journal contribution
posted on 2020-01-16, 20:33 authored by Feifan Wang, Jue Wang, Sebastian F. Maehrlein, Yingzi Ma, Fang Liu, X.-Y. ZhuThe
upper limit in LED quantum efficiency from conventional closed-shell
molecules is 25% as dictated by singlet and triplet spin statistics.
Spin-doublet organic molecules are attractive candidates to exceed
this limit, thanks to their 100% theoretical quantum efficiency in
radiative recombination. However, examples of stable spin-doublet
molecules in the solid state are rare. Here we show broad-band near-infrared
emission in the columnar π–π stacked tetrathiafulvalene
(TTF) in a metal organic framework (MOF) single crystal. The broad
emission is similar to known TTF+• doublet emission
and is stabilized in the MOF crystal. This interpretation is supported
by the observation of enhanced PL emission following UV oxidation
of the MOF crystal to increase the doublet concentration. The findings
suggest tetrathiafulvalene-based MOFs as promising materials for near-IR
light emission and the MOF structure may be a general strategy to
stabilize radical cation species in the solid state.