Investigation of the Photoluminescence Properties and Nonlinear Optical Responses of CdTe/CdS Core/Shell Quantum Dots

Abstract

Photoluminescence and nonlinear optical properties of CdTe/CdS core/shell quantum dots (QDs) have been investigated in this work. X-ray diffraction analysis demonstrated cubic crystalline structure for synthesized QDs with an average size around 8 nm. Transmission electron microscope image indicated spherical core/shell QDs. Increase of the photoluminescence quantum efficiency of QDs, confirmed formation of core/shell structure. The obtained positive sign for nonlinear refractive index indicated a self-focusing effect. The linear absorption coefficient (α) was obtained about 1.17 cm⁻¹. The nonlinear refractive index was in order of 10⁻⁸ cm²/W and the nonlinear absorption coefficient was obtained in order of 10⁻³ cm²/W with a negative sign.

Keywords:

• CdTe/CdS Core/shell QDs
• nonlinear optical responses
• photoluminescence properties
• Z-scan technique