Growth evolution and phase transition from chalcocite to digenite in nanocrystalline copper sulfide: Morphological, optical and electrical properties

Abstract

SummaryCopper sulfide is a promising p-type inorganic semiconductor for optoelectronic devices such as solar cells, due its small band gap energy and its electrical properties. In this work nanocrystalline copper sulfide (CuxS), with two stoichiometric ratios (x = 2, 1.8) was obtained by one-pot synthesis at 220, 230, 240 and 260 °C in an organic solvent and amorphous CuxS was obtained in aqueous solution. Nanoparticle-like nucleation centers are formed at lower temperatures (220 °C), mixtures of morphologies (nanorods, nanodisks and nanoprisms) are seen at 230 and 240 °C, in which the nanodisks are predominant, while big hexagonal/prismatic crystals are obtained at 260 °C according to TEM results. A mixture of chalcocite and digenite phases was found at 230 and 240 °C, while a clear transition to a pure digenite phase was seen at 260 °C. The evolution of morphology and transition of phases is consistent to the electrical, optical, and morphological properties of the copper sulfide. In fact, digenite Cu1.8S is less resistive (346 Ω/sq) and has a lower energy band gap (1.6 eV) than chalcocite Cu2S (5.72 × 105 Ω/sq, 1.87 eV). Low resistivity was also obtained in CuxS synthesized in aqueous solution, despite its amorphous structure. All CuxS products could be promising for optoelectronic applications.

Colloidal synthesis of biocompatible iron disulphide nanocrystals

“…Two of these chalcogenides, cadmium (CdS) and lead sulphides (PbS) have been widely studied [1,3,4], but could cause environmental damage. At present, non-toxic metal sulphides, such as copper sulphide, zinc sulphide and iron sulphide, are considered promising semiconductors owing do their optoelectronic properties [2,5,6]. Iron sulphide presents different crystalline phases such as troilite, marcasite, pyrrohotite and pyrite [7,8].…”

Effect of laser fluence on structural and optical properties of CuxS films grown by pulsed laser deposition at different wavelengths

“…The dominant peak at 2q=26.49°corresponds to the Chalcocite (Cu 2 S) and the (002) diffraction plane, as well as the peak at 23.08°, is associated to S and the diffraction plane is (222); the peaks at 29.27, 31.78, 47.94, 52.71 and 59.34°, are related to covellite (CuS) hexagonal phase (PDF No. 06-0464) [10,11]. The crystallinity for samples at 8.7 and 13.6 J cm −2 is missed out, as diffraction patterns show.…”

Copper: Synthesis Techniques in Nanoscale and Powerful Application as an Antimicrobial Agent

“…The electrochemical synthesis (Figure 2(c)) is based on the application of an electrical current between two electrodes (cathode and anode) separated by an electrolytic solution; the reduction process occurs on the surface of the cathode electrode [40]. Microwaves and hydrothermal treatment are new alternatives to obtain regular particle size and morphology Cu NPs [41,42]. The microwave technique consists in an electromagnetic energy with frequencies in the range of 300 MHz to 300 GHz [43][44][45], where the adequate amounts of energy influence directly the configuration of the Cu NPs.…”