Collecting up to 115% of Singlet-Fission Products by Single-Walled Carbon Nanotubes.

Abstract

In this contribution, we focused on integrating a phenylene-bridged dibenzodiazahexacene dimer (<i>o</i>-DAD), which is singlet fission (SF) active, onto single-walled carbon nanotubes (SWCNTs) as a low-energy sink for energetically low lying excited states that stem from SF. Spectroscopic and microscopic assays assisted in documenting that SWCNT/<i>o</i>-DAD feature high stability in THF as a result of electronic interactions between the individual constituents. For example, statistical Raman analysis underlined n-doping of SWCNTs in the presence of <i>o</i>-DAD. Fluorescence spectroscopy prompted an energy transfer between the individual constituents, a conclusion that was exclusively derived from the quenching of the <i>o</i>-DAD-centered fluorescence. Excitation spectroscopy with a focus on the SWCNT fluorescence confirmed independently this conclusion by showing <i>o</i>-DAD-centered features. Our work was rounded off by time-resolved transient absorption measurements with SWCNT/<i>o</i>-DAD, in which evidence was gathered for the sequential <i>o</i>-DAD-centered SF with an efficiency of 112% followed by a unidirectional energy transfer from <i>o</i>-DAD to SWCNT and a rapid deactivation. The energy transfer efficiency from SF products such as (S₁S₀)_CT and ¹(T₁T₁) exceeded the 100% threshold with values of 115%, which is conventionally found in energy transfer schemes.