Ambient synthesis and optoelectronic properties of copper iodide semiconductor nanoparticles

Electrically conducting copper iodide (CuI) nanoparticles have been synthesized at room temperature via a simple single step chemical route, using ethyl alcohol as a solvent. The resulting material was characterized by X-ray diffraction, differential scanning calorimetry, optical absorption, photoluminescence, scanning electron microscopy, energy-dispersive X-ray spectroscopy and high resolution transmission electron microscopy to assess the quality of these semiconductor nanoparticles. Thin film was deposited on copper substrate that was used to investigate temperature dependent electrical conductivity. These investigations confirm that the material is semiconductor having a negative temperature coefficient of resistivity. Thermal analysis and X-ray diffraction studies reveal that it is of low temperature γ phase. Energy-dispersive X-ray spectroscopy measurements confirm the stoichiometry of as prepared material. The shift in optical absorption edge towards lower wavelength region (Eg ∼ 4.77 eV) as compared to its bulk absorption indicates that a decrease in particle size has a significant effect. Photoluminescence peak observed at 2.90 eV is unique to its material property. These optoelectronic properties of CuI will be helpful in the development of future electronic devices.

A simple chemical route to prepare crystalline γ-phase copper iodide semiconductor.Figure optionsDownload as PowerPoint slideHighlights
► A new facile technique is developed to synthesize CuI semiconductor nanoparticles.
► As prepared material is highly crystalline γ-phase and visible fluorescent.
► It exhibits good electrical conductivity ∼10−4 (Ω cm)−1.
► Strong quantum confinement is observed, 22 nm size shows band gap shift of 1.7 eV.
► The γ-phase is thermodynamically more stable.