Transport of thermal energy at nanoscale interfaces imposes practical limitations on optoelectronic devices such as LEDs or lasers. Direct measurements of interfacial thermal conductance in semiconductor nanoparticle systems are not, however, straightforward. This presentation will discuss ultrafast spectroscopic measurements to vibrationally excite organic ligand coatings on semiconductor nanoparticles and probe heat transfer processes into the particle with precision as good as 0.1 K. Thermal energy transfer is observed in the quasi-equilibrium regime, in which phonon occupation has a well-defined temperature, and the non-equilibrium regime, in which high-energy phonons are populated on a much slower time-scale. These infrared pump, electronic probe measurements may be used to extract through-bond thermal conductance from the ligand coating to the inorganic core and the slower dissipation of heat to the surroundings, such as solvent. Results comparing dependence on size and shape, fluence, temperature, and ligand coverage will be presented.

Spectroscopic measurements of heat transfer at organic-inorganic nanoscale interfaces

ACS Spring 2022

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