Formation of mechanism and excitonic luminescence of supercritical-fluid-synthesized ZnO nanoparticles

Brian Dusolle (1) , Veronique Jubera (1) , Evgeniy Ilin (1) , Patrick Martin (2) , Gilles Philippot (1) , Matthew Suchomel (1) , Bo Iversen (3, 4) , Samuel Marre (1) , Cyril Aymonier (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 CELIA - Centre d'Etudes Lasers Intenses et Applications
3 Center for Integrated Materials Research
4 iNANO - Interdisciplinary Nanoscience Center

Extensive research on nanosized ZnO has proven that its optical properties are challenging to control due to a number of possible defects producing various emissions in the visible range. Our group proposed a low-temperature, supercritical-fluid-driven synthesis of isotropic nanosized particles that exhibit a unique and unprecedentedly pure excitonic emission, comparable to that of single crystals. The present article reports the growth mechanism at the origin of the unexpectedly pure excitonic emission as well as a more detailed study of its optical properties at liquid helium temperatures. The ZnO phase is obtained via the thermal decomposition of an intermediate ZnO2 phase. No bulk defect luminescence is detected, and the synthesis route leaves a “ZnO2-like” surface able to neutralize the formation of surface defects, which can contribute to visible emissions. The luminescence measurements were performed at liquid helium temperature to enable the identification of excitons. The investigation of the photoluminescence properties confirms a strong excitonic emission in the UV region with no visible band and sheds light on a phonon coupling with the E2 high vibrational mode.

Mots clés: Crystal structure; Excitons; Metal oxide nanoparticles; Nanoparticles; Oxides

Domaines: Matériaux

Brian Dusolle, Veronique Jubera, Evgeniy Ilin, Patrick Martin, Gilles Philippot, et al.. Formation of mechanism and excitonic luminescence of supercritical-fluid-synthesized ZnO nanoparticles. Chemistry of Materials, 2023, 35 (10), pp.4057-4067. ⟨10.1021/acs.chemmater.3c00493⟩. ⟨hal-04098593⟩