Investigation of Low Cost Solar Cells Based on Cu20.

摘要

Investigations have been conducted regarding fabrication of thin-film backwall Cu/Cu2O cells,collection efficiency measurements and analysis,MIS solar cell theory,and initiation of frontwall solar cell studies. A system was established for controlled oxidation of copper. Cu2O films on the order of 40micrometers thick typically have grain sizes greater than 100micrometers. Thin-film cells with Cu2O thickness 10micrometers that have been fabricated are more granular. Both thick-film and thin-film backwall cells have been fabricated and characterized. These cells typically have J about 0.00003 A/cm2and n 3.5. Analysis of thick-film diodes suggest that a high interface state density exists at the Cu-Cu2O junction. The thin-film cells have very low shunt resistances due to the granular structure. Spectral collection efficiency of thin-film backwall cells has been measured to be 25percent at 600nm. Assuming a reasonable collection efficiency for backwall cells,the upper limit of performance for backwall cells is projected to be 4percent. Frontwall cells have been fabricated by evaporating Cu and Pr onto polycrystalline Cu2O substrates. A maximum collection efficiency of 40percent was measured at 575nm for one of the first cells.