Synthesis of copper quantum dots by chemical reduction method and tailoring of its band gap

P G Prabhash,Swapna S Nair

doi:10.1063/1.4948747

Abstract

Metallic copper nano particles are synthesized with citric acid and CTAB (cetyltrimethylammonium bromide) as surfactant and chlorides as precursors. The particle size and surface morphology are analyzed by High Resolution Transmission Electron Microscopy. The average size of the nano particle is found to be 3 - 10 nm. The optical absorption characteristics are done by UV-Visible spectrophotometer. From the Tauc plots, the energy band gaps are calculated and because of their smaller size the particles have much higher band gap than the bulk material. The energy band gap is changed from 3.67 eV to 4.27 eV in citric acid coated copper quantum dots and 4.17 eV to 4.52 eV in CTAB coated copper quantum dots.

Highlights

Transition metal nano structures have been the focus of considerable interest due to their unique optical and electrical properties and potential applications due to their excellent luminescent properties in semiconductor electroluminescence devices, fluorescence devices, non-linear optical devices, solar energy conversion devices and light-emitting diodes for flat panel displays.[1,2,3,4,5,6]Nanoparticle represents the state of matter, somewhere between the molecular and the extended solid state
The energy band gap is changed from 3.67 eV to 4.27 eV in citric acid coated copper quantum dots and 4.17 eV to 4.52 eV in CTAB coated copper quantum dots
The band gap depends upon the particle size because of quantum confinement effect, which implies that a single material can exhibit several different colours both by absorption and emission

Summary

INTRODUCTION

Transition metal nano structures have been the focus of considerable interest due to their unique optical and electrical properties and potential applications due to their excellent luminescent properties in semiconductor electroluminescence devices, fluorescence devices, non-linear optical devices, solar energy conversion devices and light-emitting diodes for flat panel displays.[1,2,3,4,5,6]. It is well known that the optical properties like absorption of the nanosized metals differ drastically from the properties of the bulk material due to the change in energy band gap. The band gap depends upon the particle size because of quantum confinement effect, which implies that a single material can exhibit several different colours both by absorption and emission. Quantum confinement of both electron and hole in all three dimensions leads to an increase in effective band gap energy of the material with decreasing the size of the particle.

EXPERIMENTAL TECHNIQUES

RESULTS AND DISCUSSION

CONCLUSION