Improvements in stoichiometry and stability of p-CuxS in thin-film CdS solar cells

Abstract

To counter the problem of instability, irreproducibility, and low stoichiometry of p-CuxS layers in thin-film CdS solar cells, a new field-assisted chemiplating process of barrier formation is described. Using the dc-forming potential as a first-order variable, nominal deviation from Cu2S composition without any dependence on external process parameters has been obtained. The stability of higher composition CuxS is attributed to the formation of a Cd++, rich barrier layer at the growing CuxS interface towards the CdS side, as inferred from the spectral response and Auger Cu and Cd compositional depth profile of the solar cells.

Electrodeposition of Semiconductors

“…(14.26) by use of the triethylenetetramine masking agent, which reacts with Cu(II) and Cd(II). Al-Dhafiri and coworkers [120] showed that the phase of the Cu x S layers formed on CdS by dipping in a solution containing Cu ions can be controlled by applying a potential to the CdS substrate and that the most efficient photovoltaic cells made using this technique were produced when the CdS was biased in a narrow range between 0.01 and 0.02 V. It has been suggested that the applied bias affects the exchange of the Cd 2þ and Cu þ ions involved in the formation of the Cu x S by causing the formation of a Cd-rich layer at the Cu x S/CdS interface and preventing the diffusion of Cu þ ions deeper into the CdS [120][121][122]. In their earlier work Al-Dhafiri and coworkers [121] suggested that both substrate and postdeposition anneal play an important role in determining the stability of the CdS-Cu 2 S photovoltaic devices as well.…”

CuS-based thin films for architectural glazing applications produced by co-evaporation: Morphology, optical and electrical properties

“…A strong research activity was focused on Cu x S during the 1980s in order to achieve large scale production of stable solar cell devices with CdS [4][5][6]. However, it practically stopped a few years later after lacking encouraging results.…”

Phase-Selective Synthesis of Copper Sulfide Nanocrystals

“…Copper sulfide (Cu x S, x = 1−2) is well-known to form a wide variety of non-stoichiometric and mixed phases, of which at least five are known to be stable at room temperature: covellite (CuS) in the “sulfur-rich region”; and anilite (Cu 1.75 S), digenite (Cu 1.8 S), djurleite (Cu 1.95 S), and chalcocite (Cu 2 S) in the “copper-rich region” . Cu x S compounds in different stoichiometries have a wide range of well-established and prospective applications, for example, as p-type semiconductors, solar cells, superionic materials, and in many chemical sensing applications . Because of their unique optical and electrical properties, they are also widely applied as thin films , and composite materials. , Recently, Cu x S was demonstrated as a potential nanometer-scale switch …”

“…Cu x S compounds in different stoichiometries have a wide range of well-established and prospective applications, for example, as p-type semiconductors, solar cells, superionic materials, and in many chemical sensing applications . Because of their unique optical and electrical properties, they are also widely applied as thin films , and composite materials. , Recently, Cu x S was demonstrated as a potential nanometer-scale switch …”