Title :
Effects of thermal stressing on CdTe/CdS solar cells
Author :
Tetali, B. ; Viswanathan, V. ; Morel, D.L. ; Ferekides, C.S.
Author_Institution :
Center for Clean Energy & Vehicles, Univ. of South Florida, Tampa, FL, USA
Abstract :
The effects of thermal stressing on CdTe/CdS thin film solar cells have been investigated. Cadmium telluride solar cells fabricated by close-spaced sublimation, and contacted with Cu-based back contacts have been subjected to temperatures ranging from 70 to 120°C in inert ambient for over 3500 hours. The average starting Voc and ff for all stressed devices were 840 mV and 72% respectively. The devices were periodically removed from the stress environment and their light and dark J-V characteristics were measured. It has been found that all cells exhibited some degree of degradation, which was accelerated with temperature. Changes in device characteristics appeared to be gradual for temperatures in the range of 70-90°C. In all cases a significant portion of the observed degradation took place within the first 500-600 hours. SIMS analysis indicated that the stress process resulted in Cu-accumulation near the CdTe/CdS junction, suggesting that Cu is at least partially responsible for the observed junction degradation.
Keywords :
II-VI semiconductors; cadmium compounds; copper; dark conductivity; doping profiles; photoconductivity; secondary ion mass spectra; semiconductor device measurement; solar cells; thermal stresses; 3500 hour; 500 to 600 hour; 70 to 120 degC; 840 mV; CdTe-CdS; CdTe/CdS solar cells; Cu; Cu-based back contacts; J-V characteristics; SIMS analysis; close-spaced sublimation; degradation; device characteristics; thermal stressing; Copper; Degradation; Glass; Manufacturing; Ovens; Photovoltaic cells; Stress measurement; Temperature distribution; Thermal stresses; Transistors;
Conference_Titel :
Photovoltaic Specialists Conference, 2002. Conference Record of the Twenty-Ninth IEEE
Print_ISBN :
0-7803-7471-1
DOI :
10.1109/PVSC.2002.1190636
