Title :
Impact of sheet resistance and contact shading on ´Suns-V/sub OC/´ measurements on thin-film solar cells
Author :
Harder, Nils-Peter ; Sproul, Alistair B. ; Brammer, Torsten ; Aberle, Armin G.
Author_Institution :
Centre of Excellence for Adv. Silicon Photovoltaics & Photonics, Univ. of New South Wales, Sydney, NSW, Australia
Abstract :
The measurement of the open-circuit voltage (V/sub OC/) as a function of the illumination intensity (Suns-V/sub OC/) is a useful tool for characterising solar cells, giving a characteristic curve with virtually no influence from series resistance. In particular, Suns-V/sub OC/ measurements allow the extraction of the diode properties without a complete contacting scheme. In this paper, using resistive network calculations, we show that the combination of contact shading and high sheet resistance can cause severe deviations of the measured Suns-V/sub OC/ curve from that measured without contact shading and/or negligible sheet resistance. These deviations bear the danger of erroneous assessment of the fundamental diode properties. For sheet resistances typical for thin layers of doped hydrogenated amorphous Si (a-Si:H), even the shadow of the tip of a needle-shaped contacting probe (O/spl sime/5 /spl mu/m) is sufficient to cause a severely distorted Suns-V/sub OC/ curve. Results of experiments performed on a microcrystalline p-i-n Si thin-film solar cell with an a-Si:H n/sup +/ layer are presented and explained within the framework of the resistive network model.
Keywords :
amorphous semiconductors; electrical resistivity; elemental semiconductors; hydrogen; p-i-n diodes; semiconductor device models; semiconductor thin films; silicon; solar cells; Si:H; contact shading; diode properties; hydrogenated amorphous silicon; microcrystalline p-i-n Si thin-film solar cell; needle shaped contacting probe; open-circuit voltage; resistive network calculations; sheet resistance; thin film solar cells;
Conference_Titel :
Photovoltaic Energy Conversion, 2003. Proceedings of 3rd World Conference on
Conference_Location :
Osaka, Japan
Print_ISBN :
4-9901816-0-3