Quantifying Size Effects on Thermal Transport in CsPbBr3 Nanocrystal Films

JY Park and D Chen and SR Li and Y Xia and BT Diroll and PJ Guo, NANO LETTERS, 25, 14286-14292 (2025).

DOI: 10.1021/acs.nanolett.5c03215

Colloidal lead halide perovskite nanocrystals (LHP NCs) are promising semiconductor materials for optoelectronic applications due to their strong quantum confinement, near-unity photoluminescence quantum yields, and tunable emission characteristics. However, their modest thermal stability remains a challenge, particularly at smaller core diameters due to enhanced phonon scattering at inorganic core-organic ligand interfaces. In this study, we directly quantify size-dependent thermal conductivity (kappa) in lecithin-capped CsPbBr3 NC thin films using a transducer-free, vibrational pump-visible probe (VPVP) spectroscopy technique. A mid-infrared pump thermally excites the ligand shell, while a broadband probe tracks transient reflectance change correlated to lattice temperature decay. Finite-element modeling of the decay dynamics yields kappa values from 0.13 to 0.16 Wm-1K-1 for NC films with sub-10 nm core diameter, significantly lower than those of its bulk counterpart. A steep kappa suppression with decreasing NC size emphasizes the dominant role of ligand shells and boundary effects in thermal transport.

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