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The nanoscale electrical and mechanical properties in the CdTe thin films solar cells were investigated using the scanning probe microscopy. The comparative localized electrical and mechanical properties between as-grown and CdCl2 treated CdTe thin films for the grain and grain boundaries were studied using the conductive atomic force microscopy (cAFM) and force modulation microscopy (FMM). An increased electrical behavior and decreased elastic stiffness in the CdCl2 treated thin films were recorded to elucidate the impact from the grain growth of CdTe grains. On applying a simulated working electrical bias into the CdTe thin-film solar cells, the electric field across the CdTe film can increase the softness of CdTe thin film. The results imply the presence of a potential mechanical failure site in the CdTe grain boundary, which may lead to device degradation.
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CdMgTe as an Electron Reflector for MgZnO/CdSeTe/CdTe Solar Cells
CdMgTe with a 1.8-eV band gap was deposited at the back of MgZnO/CdSeTe/CdTe superstrates to create a conduction band barrier and reduce back surface recombination. To minimize CdCl2 passivation loss, substrate preheat time was varied. Photoluminescence, carrier lifetime, and quantum efficiency showed improvement with shorter preheat and secondary ion mass spectrometry profiles showed retention of CdCl2 passivation for short CdMgTe preheat. An HCl acid etch treatment and CdTe cap layer were incorporated independently after the CdMgTe on additional devices to minimize magnesium oxidation and the CdTe cap device showed initial promise with device efficiency reaching 13.1%.
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- Award ID(s):
- 1726898
- PAR ID:
- 10122048
- Date Published:
- Journal Name:
- IEEE PVSC 2019
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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