Dynamic lattice distortions driven by surface trapping in semiconductor nanocrystals

Abstract

Nonradiative processes limit optoelectronic functionality of nanocrystals and curb their device performance. Nevertheless, the dynamic structural origins of nonradiative relaxations in nanocrystals are not understood. Here, femtosecond electron diffraction measurements corroborated by atomistic simulations uncover transient lattice deformations accompanying radiationless electronic processes in semiconductor nanocrystals. Investigation of the excitation energy dependence shows that hot carriers created by a photon energy considerably larger than the bandgap induce structural distortions at nanocrystal surfaces on few picosecond timescales associated with the localization of trapped holes. On the other hand, carriers created by a photon energy close to the bandgap result in transient lattice heating that occurs on a much longer 200 ps timescale, governed by an Auger heating mechanism. Elucidation of the structural deformations associated with the surface trapping of hot holes provides atomic-scale insights into the mechanisms deteriorating optoelectronic performance and a pathway towards minimizing these losses in nanocrystal devices.

arXiv comment17 pages, 4 figures

References in corpus (5)

• The influence of Auger recombination on the performance of quantum-dot light-emitting diodes
• The effect of Auger heating on intraband carrier relaxation in semiconductor quantumrods
• Influence of the Surface of a Nanocrystal on its Electronic and Phononic Properties
• Transferable Pair Potentials for CdS and ZnS Crystals
• On the Nature of Trapped-Hole States in CdS Nanocrystals and the Mechanism of their Diffusion

Cited by in corpus (2)

• Simulations of nonradiative processes in semiconductor nanocrystals
• Theory of photoluminescence spectral line shapes of semiconductor nanocrystals