Cl diffusion in CdTe solar cells activated by gaseous CHClF2 atmosphere

The activation treatment is consider of dramatic importance for CdTe solar cells. The most effective activation processes are based on chlorine compounds. However it is still not clear how Cl diffusion depends on the chlorination method. In this paper we activated CdTe solar cells by gaseous CHClF2 and investigated the Cl presence by TEM and XPS. Preliminary results show clear presence of Cl trapped at the CdS/CdTe interface. Thanks to the flexibility of the gaseous activation treatment, further samples will be prepared in order to force larger quantity of Cl into the absorber and they will be similarly analyzed. TEM will be used to investigate Cl presence at grain boundaries and XPS to determine the compounds formed by Cl

Photoluminescence imaging analysis of doping in thin film CdS and CdS/CdTe devices

The use of photoluminescence (PL) imaging analysis to assess the effectiveness of the passivation treatment due to the presence of chlorine in CdS thin films has been investigated. In this work, we show that the chlorine doping effect in the CdS window layer can be detected by PL imaging analysis, due to the formation of a defect complex of sulfur vacancy and ClS (VS-ClS) and complexes between halogen ions and cadmium vacancies (VCd-ClS). CdTe devices with differently doped CdS layers were investigated. PL imaging, TEM, IV performance indicators and EQE analysis were performed to understand the effect of the different dopants on the electrical performances of CdTe devices