Cobalt and Iron Co-doped ZnSe Nanocrystals: Mid-IR Luminescence at Room Temperature

Fe:Co:ZnSe nanocrystals with different co-doping ratios of Fe²⁺/Co²⁺ ions were fabricated by hydrothermal synthesis.

These nanocrystals are spherical in shape and exhibit a cubic sphalerite structure with an average grain size of about 15 nm. Through the energy conversion between Co²⁺ and Fe²⁺ ions, mid-infrared fluorescences at 3.3 μm and 4.4 μm were detected under 1550 nm laser excitation at room temperature.

The facile method used in the present work from a research team led by Prof. Dr. GUO Haitao  from Xi'an Institute of Optics and Precision Mechanics (XIOPM) of the Chinese Academy of Sciences (CAS) avoids the mid-infrared quench effect induced by the organic molecular introduced in the past preparation process.

The fluorescence band of 4.4 μm in the Fe:Co:ZnSe nanocrystals is thought to be an overlapping emission involving the peak centered at 4648 nm corresponding to the Co²⁺ : ⁴T₁(F) → ⁴T₂ (F) energy transition and the peak centered at 4273 nm corresponding to Fe²⁺ : ⁵T₂(D) → ⁵E (D) energy transition.

These high-quality optically active nanomaterials show potential applications in mid-infrared devices such as composite fiber-amplifiers and lasers materials.

FE-TEM、HRTEM 、EDS spectra and the element distribution of 0.6 mol % Fe 3 mol % Co: ZnSe nanocrystals. (Image by XIOPM)

(Original research article “Journal of Luminescence”(2020) http://dx.doi.org/10.1016/j.jlumin.2020.117102 )