Electrosynthesis and Electrochemical Characterization of a Thin Phase of Cu_xS (x → 2) on ITO Electrode

Abstract

Cu x S (x → 2) thin films were obtained by sulfidization of copper thin films previously obtained by spin-coating from a dichloromethane solution of [Cu(II)(2-ethyl hexanoate)2(H2O)2] deposited on ITO substrate, irradiated with UV light and electrochemically reduced. Through cyclic voltammetry experiences performed in a 0.05 M Na2B4O7 buffer solution containing 5 mM Na2S, the electroformation mechanism of Cu x S phase is controlled by a first electron transfer, obtaining an initial formation of Cu(HS)ads that evolves to a Cu x S phase. Potentiostatic current transient recorded in the potential range of −0.8 V ≤ E ≤ −0.7 V showed that the nucleation and growth mechanism of the Cu x S phase obeys a two-dimensional instantaneous process with diffusional and charge-transfer contributions. AFM analysis of the deposits shows that Cu x S phase is preferentially deposited in the valleys left by ITO particles. The average size of Cu x S particles is close to 20 nm. Cyclic voltammetry results, electromotive force determination in the Cu/ /Cu x S galvanic cell, EDAX, and UV analysis demonstrate that the stoichiometric factor x in Cu x S is close to 2. The electro-obtained Cu x S phase was unstable and evolved to other nonstoichiometric compounds at open circuit. The processes responsible for the instability were the own oxidation of Cu x S phase and the water reduction that takes place over Cu x S and bare ITO particles. The last process was studied by electrochemical impedance spectroscopy. Photoelectrochemical measurements in the stability potential range of the Cu x S phase shows that the electro-obtained phase presents a p-type conductivity.

In situ growth of CuS thin films on functionalized self-assembled monolayers using chemical bath deposition

“…So far, a variety of methods were employed to the deposition of CuS thin films, such as chemical vapor deposition [25], thermal coevaporation [2], successive ionic layer adsorption and reaction (SI-LAR) [9], photochemical deposition [26], electrochemical method [27] and chemistry bath deposition (CBD) [28][29][30]. Among these, the chemical bath deposition is an attractive technique for the deposition of semiconductors as it does not require sophisticated instrumentation like vacuum system and other expensive equipments.…”

Directionally dendritic growth of metal chalcogenide crystals via mild template-free solvothermal method

“…Further more, Single HgS (cinnabar) crystal is a famous natural chiral crystal and expected to be used for stereochemical reactions [12]. Much effort has been devoted to the synthesis of metal chalcogenide of various morphologies, such as rods [13], wires [14], tubes [15], etc., with various techniques and methods involving microwave synthesis [16], sonasynthesis [17] and electrochemical deposition [18] and so on. The formation of spatial patterns of metal chalcogenide is of special interest because subtle influencing factors may result in completely different crystal shape.…”

The effect of complexing agent on crystal growth, structure and properties of nanostructured Cu2−xS thin films

“…Cu 2Àx S as materi- 13 als, particularly in its thin film form, maintain transmittance in the 14 infrared, low reflectance (<10%) in the visible, and relatively high 15 reflectance (> 15%) in the near-infrared region, which are ideal 16 characteristics for solar energy adsorption [2]. Copper sulfide can 17 exist as seven solid phases with various stoichiometries, Cu 2Àx S, 18 (0 < x < 1), including Cu-rich Cu 2 S (chalcocide), Cu 1.97 S (djurleite), 19 Cu 1.8 S (digenite), Cu 1.75 S (anilite) Cu 1.12 S (yarrowite), Cu 1.06 S 20 (talnakhite) and CuS (covellite) [3,4]. Nair and coworkers [5] 21 reported that all of Cu 2Àx S compounds exhibited a p-type 22 semiconductor characteristic with copper vacancy defect as 23 acceptors, which is the most important reason for their applica- 24 tions in the photovoltaic devices.…”

“…He and his coworkers synthesized uniform, 44 small sized CuS NCs prepared via a facile sol-gel method without 45 using template and complicated post-treatment [14]. Moreover, a 46 variety of methods were employed to deposit Cu 2Àx S thin films, 47 such as chemical vapor deposition, thermal co-evaporation [15], 48 photochemical deposition [16], electrochemical method [17] 49 and chemical bath deposition (CBD) [18][19][20][21]. Among these, 50 the chemical bath deposition is an attractive technique for 51 the deposition of semiconductors as it does not require sophisticated 52 instrumentation like vacuum systems or other expensive equip-53 ment.…”