COMPARISON OF CSS-CdTe AND PVD-CdTe WITH DIFFERENT ACTIVATION PROCESSES

摘要

CdTe polycrystalline thin film solar cells have a strong potential in scalability. They have shown long-termstable performance and high efficiency up to 16.5% under AM1.5 illumination. Amongst several attractive features highchemical stability of CdTe and a simple compound formation are the most important ones for large area production of solarmodules. A further simplification has been done by substituting the CdCl_2 step by treating CdTe films in an atmospherecontaining a non toxic gas that is inert at room temperature, like HCFCl_2, that belongs to the Freon~? family. The treatment istypically done at a temperature of 400°C, for a few minutes and in an atmosphere of 100 mbar of Ar containing 15% ofHCFCl_2. The change in the morphology of CdTe films after treatment is very similar to that obtained with CdCl_2 treatmentand an increase in the size of small grains is always observed. This process has been applied by N. Romeo et al. CdTe thinfilms deposited by on close spaced sublimation (CSS) with very interesting results (15.8% efficiency). In this work theapplication of this novel “activation process” on physical vapor deposited cells will be described and a comparison ofphysical and electrical features with the standard process and with CSS deposited layers will be presented.