Polycrystalline thin film solar cells of II-VI compound semiconductors are important because of their low cost, high efficiency and stable performance. Flexible and lightweight solar cells are interesting for a variety of terrestrial and space applications that require a very high specific power (ratio of output electrical power to the solar module weight). Moreover, light modules are advantageous in terms of transport and mounting. We have previously described the development of flexible CdTe/CdS solar cells on polyimide substrates with a novel method; efficiencies of 8.6 % were reported. Further improvements in the processing have now increased the solar cell efficiency to 11%. The CdTe solar cell is fabricated in a “superstrate” configuration where the light passes through the polyimide substrate. Absorption of the incident light and possible degradation of polyimide under UV and particle irradiation are the major limitations of this configuration. To overcome these a new approach is introduced here. The CdTe/CdS/TCO stacks are grown on a NaCl/glass substrate. After the solar cell has been processed, a polymer layer is spin coated on top and the flexible solar cells are detached from the glass by dissolving the NaCl buffer layer. Solar cells of 7.3% efficiency have been obtained.
Development of High Efficiency Flexible CdTe Solar Cells
ROMEO, Alessandro;
2002-01-01
Abstract
Polycrystalline thin film solar cells of II-VI compound semiconductors are important because of their low cost, high efficiency and stable performance. Flexible and lightweight solar cells are interesting for a variety of terrestrial and space applications that require a very high specific power (ratio of output electrical power to the solar module weight). Moreover, light modules are advantageous in terms of transport and mounting. We have previously described the development of flexible CdTe/CdS solar cells on polyimide substrates with a novel method; efficiencies of 8.6 % were reported. Further improvements in the processing have now increased the solar cell efficiency to 11%. The CdTe solar cell is fabricated in a “superstrate” configuration where the light passes through the polyimide substrate. Absorption of the incident light and possible degradation of polyimide under UV and particle irradiation are the major limitations of this configuration. To overcome these a new approach is introduced here. The CdTe/CdS/TCO stacks are grown on a NaCl/glass substrate. After the solar cell has been processed, a polymer layer is spin coated on top and the flexible solar cells are detached from the glass by dissolving the NaCl buffer layer. Solar cells of 7.3% efficiency have been obtained.
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