A SIMPLE METHOD TO MAKE NON-ETCHING BACK CONTACT FOR CDTE SOLAR CELLS WITHOUT USING COPPER

摘要

The classical CdTe solar cell back contact formation procedure generally requires CdTe surface treatment such as chemical etching or CdTe surface doping using Cu compounds before depositing metal back contact to overcome Schottky barrier formation. In this manuscript, we present a simple procedure which can help to produce a back contact without etching and using copper. After the CdCl_2 activation process, methanolic SbCl_3 solution was applied onto the CdTe surface and subsequently heat treated for very short time. The X-ray photo electron spectroscopy measurements indicate the formation of a thin Sb_2Te_3 interlayer on the CdTe. The SbCl_3 based back contact yields solar cell performance comparable to the reference cell prepared with nitric-phosphoric acid etching procedure. In general, the SbCl_3 based solar cells show strong roll-over phenomena. In addition to the Sb_2Te_3 interlayer formation, the formation of complex native oxides might limit the free carrier concentration in the interlayer and might be responsible for the roll-over phenomena. Improved SbCl_3 solution application on CdTe surface and optimized thermal treatment can probably yield higher efficiency solar cells than the reference cell.