Luminescence mechanisms of defective ZnO nanoparticles.

6533b831fe1ef96bd129866a

RESEARCH PRODUCT

Luminescence mechanisms of defective ZnO nanoparticles.

Lavinia Vaccaro Gianpiero Buscarino Roberto Lorenzi Marco Cannas Reinhard Schneider Radian Popescu Franco Mario Gelardi Dagmar Gerthsen Simonpietro Agnello Fabrizio Messina P. Camarda P. Camarda

subject

Materials science Photoluminescence General Physics and Astronomy Nanotechnology 02 engineering and technology Electron time resolved photoluminescence 010402 general chemistry 01 natural sciences symbols.namesake Lattice constant Physical and Theoretical Chemistry High-resolution transmission electron microscopy Raman FIS/03 - FISICA DELLA MATERIA Wurtzite crystal structure business.industry Settore FIS/01 - Fisica Sperimentale 021001 nanoscience & nanotechnology 0104 chemical sciences Absorption edge ZnO nanoparticles laser ablation Luminescence microscopy excitons defects symbols TEM ZnO Optoelectronics oxide nanoparticle 0210 nano-technology business Raman spectroscopy Luminescence

description

ZnO nanoparticles (NPs) synthesized by pulsed laser ablation (PLAL) of a zinc plate in deionized water were investigated by time-resolved photoluminescence (PL) and complementary techniques (TEM, AFM, μRaman). HRTEM images show that PLAL produces crystalline ZnO NPs in wurtzite structure with a slightly distorted lattice parameter a. Consistently, optical spectra show the typical absorption edge of wurtzite ZnO (Eg = 3.38 eV) and the related excitonic PL peaked at 3.32 eV with a subnanosecond lifetime. ZnO NPs display a further PL peaking at 2.2 eV related to defects, which shows a power law decay kinetics. Thermal annealing in O2 and in a He atmosphere produces a reduction of the A1(LO) Raman mode at 565 cm(-1) associated with oxygen vacancies, accompanied by a decrease of defect-related emission at 2.2 eV. Based on our experimental results the emission at 2.2 eV is proposed to originate from a photo-generated hole in the valence band recombining with an electron deeply trapped in a singly ionized oxygen vacancy. This investigation clarifies important aspects of the photophysics of ZnO NPs and indicates that ZnO emission can be controlled by thermal annealing, which is important in view of optoelectronic applications.

year	journal	country	edition	language
2016-06-03	Physical chemistry chemical physics : PCCP

10.1039/c6cp01513a https://pubmed.ncbi.nlm.nih.gov/27251452