2024 Robert H. Crabtree Lecture: 21st Century Alchemy: Making Copper Look Like a Noble Metal

Please join the Yale Department of Chemistry for the 2024 The Robert Howard Crabtree Lecture with keynote speaker Mark E. Thompson, professor of chemistry and chemical engineering and materials science, University of Southern California.

 

My talk will focus on the photophysical and electroluminescent properties of two coordinate copper, silver and gold carbene complexes, i.e. (carbene)MI(donor), where the carbene acts as an acceptor and the donor is an amide or aryl group.  These complexes show high phosphorescence quantum yield (PL = 0.7 – 1.0), giving radiative lifetimes in 0.2-3 s regime, with emission lines spanning from the violet to red.  The “tuning” of emission between violet and red involves careful manipulation of the acceptor (carbene) and donor ligands to control the donor-acceptor energy difference.    These photophysical properties rival those seen only for noble metal chromophores/luminophores previously.

 

Cryogenic photophysical measurements show these (carbene)MI(donor) complexes emit via thermally assisted delayed fluorescence (TADF).  We have prepared organic LEDs with these dopants and achieved ~ 100% EL quantum efficiency for blue and green emissive OLEDs at comparatively low drive voltages.  By careful ligand design we have achieved radiative lifetimes (carbene)MI(donor) complexes as low as 250 ns, while maintaining a high PL. Binuclear analogs show an increase in radiative rate. I will talk about our most recent model for what factors control the emission rates in these complexes and outline how to achieve fast (and slow) excited state decay.

 

I will also discuss the use of these materials as sensitizers for photo-electrochemical processes.  We have fond that these cMa materials can be efficient sensitizers for water reduction, when paired with a cobalt based electrocatalyst.  Giving good yields of hydrogen from water when irradiated at 470 nm.  We have also found that gold and copper nanoparticles are formed under irradiation that can also serve as catalysts for water reduction.  We are working toward stabilizing cMa complexes to prevent the formation metal nanoparticles on photolysis and will discuss our work in that direction, as well as our efforts to red shift the sensitizer absorption bands into the middle of the visible spectrum.

 

This seminar can be viewed at this link: Panopto