Analytical Techniques for the Determination Trace Impurities in Ii-Vi Compounds

摘要

The operating and failure mechanisms of Cu2S:CdS thin film solar cells were examined. The short circuit current of pilot production cells was found to be sensitive to the uniformity of Zn plating and to the texture of the metallized plastic substrate. The reason for this sensitivity is unknown, but it is probably related to the influence that the Zn plating has on the CdS film structure and on the ohmicity of the base contact. Extensive literature and experimental studies on the various forms of cuprous sulfide were carried out. An important experimental result was the discovery of the phase changes that result when the initially formed chalcocite is exposed to air, even at room temperature. Djurleite appears to be the phase present in normal cells. The phase transition that occurs in the vicinity of 100C is reversible and apparently does not damage the cell. The surface of the cuprous sulfide must be oxidized in order to obtain a strong photovoltaic effect. A reduced surface leads to excessive surface recombination probably aided by a surface junction having a polarity opposite to that of the Cu2S:CdS heterojunction. The threshold voltage for electrolytic deposition of Cu from Cu2S is the potential of a Cu-vacancy concentration cell in which the activity of Cu at the cathode is unity. (Author)