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Search for Factors Determining the Photodegradation in High-Efficiency a-Si:H-Based Solar Cells; Annual Technical Progress Report, 16 January 1998-15 January 1999

Technical Report ·
DOI:https://doi.org/10.2172/9814· OSTI ID:9814
This report describes studies on glow discharge (GD) and hot-wire a-Si-based samples by the University of North Carolina-Chapel Hill during Phase I. We have characterized H-bonding and its light-induced changes by using infrared (IR) and differential IR (DIR). For the less stable film, there is a simultaneous decrease {approx} 2040 cm{sup -1} and increase {approx} 1880 cm{sup -1}; for the more-stable samples, the DIR near 2000 cm{sup -1} increases upon light-soaking. Nuclear magnetic resonance (NMR) dipolar relaxation time T{sub 1D} of the clustered H is slightly shorter, but the T{sub 1D} of the isolated H is 4 times longer in hot-wire (HW) film than that in GD films. The results indicate that the local motion of the isolated H is much slower in HW compared to that in GD film. High-Temperature NMR results show a second narrow line (less than 1 kHz wide) as the temperature is raised. In stress measurements, it is clearly shown that HW films with lower hydrogen content show lower compression. A photoinduced increase of the compression on the order of 10{sup -4} of the initial value upon light-soaking was found to be similar in all a-Si:H films which exhibit different amounts of Staebler-Wronski (SW) degradation. Hence, the volume expansion is not directly related to SW effect. Also, we have measured the electric field profile in a-Si:H and a-SiGe:H solar cells, and the results agreed with computer simulation.
Research Organization:
National Renewable Energy Lab., Golden, CO (US)
Sponsoring Organization:
US Department of Energy (US)
DOE Contract Number:
AC36-99GO10337
OSTI ID:
9814
Report Number(s):
NREL/SR-520-26522; ON: DE00009814
Country of Publication:
United States
Language:
English