Low-temperature photoluminescence of CuSe2 nano-objects in selenium thin films

Abstract

Thin films of CuSe 2 nanoparticles embedded in selenium matrix were prepared by vacuum evaporation method on a glass substrate at room temperature. The optical properties of the films were investigated by photoluminescence spectroscopy (T = 20-300 K) and UV-VIS spectroscopy (T = 300 K). Surface morphology was investigated by scanning electron microscopy. The band gap for direct transition in CuSe 2 was found to be in the range of 2.72-2.75 eV and that for indirect transition is in the range of 1.71-1.75 eV determined by UV-VIS spectroscopy. On the other hand, selenium exhibits direct band gap in the range of 2.33-2.36 eV. All estimated band gaps slightly decrease with the increase of the film thickness. Photoluminescence spectra of the thin films clearly show emission bands at about 1.63 and 2.32 eV at room temperature, with no shift observed with decreasing temperature. A model was proposed for explaining such anomaly.

Homogeneity- and Stoichiometry-Induced Electrical and Optical Properties of Cu-Se Thin Films by RF Sputtering Power

“…The metal chalcogenide semiconductor Cu-Se is present in a variety of phases and crystallographic forms. It exists not only in various stoichiometric compositions, including CuSe, CuSe 2 , Cu 3 Se 2 , Cu 5 Se 4 , and Cu 7 Se 4 , but also in non-stoichiometric forms represented by CuSe 2−x and Cu 2−x Se [ 2 ]. Stoichiometric CuSe 2 refers to the ideal composition where the ratio of the Cu atoms to the Se atoms is precisely 1:2.…”

Molecular Decomposition Routes of Diaryl Diselenide Precursors in Relation to the Phase Determination of Copper Selenides

“…Copper selenides are an excellent example, and target for understanding how phase is controlled in bottom-up syntheses as the family is diverse in structure and consequently function. Copper selenides have been studied for their thermoelectric, semiconductor, and plasmonic behavior. − Copper selenides are also intermediates in the synthesis of important ternary semiconductors such as the photovoltaic material copper indium gallium selenide (CIGS), Cu­(InGa)­Se 2 , and thermoelectric CuAgSe 2 . − …”

“…This paper analyzes the use of copper metal, an often-overlooked component, in nanocrystal syntheses. Copper selenides were chosen specifically because they offer an important Lewis acid target because of their uses in thermo- and opto-electronics. − While often rare and difficult to synthesize, novel metastable phases of copper chalcogenides may be crucial for advancements in these applications.…”

Template free-synthesis of cobalt–iron chalcogenides [Co0.8Fe0.2L2, L = S, Se] and their robust bifunctional electrocatalysis for the water splitting reaction and Cr(vi) reduction

“…44–47 Many transition metal selenides of the type MSe 2 (here M = Fe, Co, Mo, Ni, Cu, and Mn) were used as an electrode in energy conversion or storage devices such as solar cells, battery, super capacitor, fuel cells, sensors, and in water-splitting reactions (HER and OER). 48–53 Xiao et al succeeded in depositing lamellar structured nanosheets of CoSe 2 on the Ti plate (CoSe 2 NS@Ti) by an in situ method, and they used it directly as a cathode for superior hydrogen evolution activity. 54 An active strategy of attaining advanced properties in the nanoscale regime is doping CoSe2 crystal structure with another element with the same electronic configuration and atomic radius.…”