Strain Induced Polarization in CdSe(x)S(1-x)/Cd(x)Zn(1-x)S Seeded Nanorods with Graded Composition
Seeded semiconductor nanorods represent a unique family of quantum confined materials that manifest characteristics of mixed dimensionality. They show polarized emission with high quantum yield and fluorescence switching under an electric field, features that are desirable for use in display technologies and other optical applications. So far, their robust synthesis has been limited mainly to CdSe/CdS heterostructures, thereby constraining the spectral tunability to the red region of the visible spectrum. Lately, a novel synthesis of CdSexS1-x/CdxZn1-xS seeded nanorods with a radially graded composition was presented. These seeded nanorods show bright and highly polarized green emission with minimal intermittency, as confirmed by ensemble and single nanorods optical measurements. Using Finite Element simulation and multiband k·p theory, we analyze the potential influence of several factors affecting excitonic emission and show that strain induced by the ZnS in the shell is the mechanism promoting linear polarization. It favors energetically light hole excitons over heavy hole ones, via deformation potential, and makes their radiative recombination faster via piezoelectricity. Thus, the controlled addition of Zn influences and improves the nanorods’ optoelectronic performance by providing an additional handle to manipulate the degree of linear polarization and the quantum confinement beyond the common size control approach. These nanorods may be utilized in applications that require the generation of a full, rich spectrum such as energy-efficient displays and lighting.
Authors: Yossi Panfil, Hebrew University of Jerusalem, Israel
Ido Hadar, Hebrew University, United States
Uri Banin, Hebrew University, Israel
Corresponding: Yossi Panfil efraim.panfil@mail.huji.ac.il
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