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Optical Simulations of the Effects of Transparent Conducting Oxide Interface Layers on Amorphous Silicon Solar Cell Performance

Published online by Cambridge University Press:  17 March 2011

Gelio M. Ferreira
Affiliation:
Materials Research Laboratory and Center for Thin Film Devices, The Pennsylvania State University, University Park, PA 16802
Andre S. Ferlauto
Affiliation:
Materials Research Laboratory and Center for Thin Film Devices, The Pennsylvania State University, University Park, PA 16802
Pablo I. Rovira
Affiliation:
Materials Research Laboratory and Center for Thin Film Devices, The Pennsylvania State University, University Park, PA 16802
Chi Chen
Affiliation:
Materials Research Laboratory and Center for Thin Film Devices, The Pennsylvania State University, University Park, PA 16802
Hien V. Nguyen
Affiliation:
Materials Research Laboratory and Center for Thin Film Devices, The Pennsylvania State University, University Park, PA 16802
Christopher R. Wronski
Affiliation:
Materials Research Laboratory and Center for Thin Film Devices, The Pennsylvania State University, University Park, PA 16802
Robert W. Collins
Affiliation:
Materials Research Laboratory and Center for Thin Film Devices, The Pennsylvania State University, University Park, PA 16802
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Abstract

Spectroscopic ellipsometry (SE) analysis of so-called “specular” (macroscopically smooth) and “textured” (macroscopically rough) thin film amorphous silicon (a-Si:H) based solar cell structures demonstrates the need to incorporate interface layers into the multilayer stack in order to simulate the observed Stokes vector of the specularly-reflected beam. In most cases, these layers can be attributed to microscopic roughness (e.g., at the SnO2/p-layer/i-layer interface in a-Si:H p-i-n solar cells), as verified by atomic force microscopy (AFM). In limited cases, the layers may include regions wherein chemical intermixing also occurs (e.g., at the ZnO/Ag interface in back-reflectors), particularly for overlying films prepared by sputtering. In spite of the clear evidence for the existence of interface layers, they have been neglected in previous simulations of the optical quantum efficiency (QE) of the solar cells. In this study, we incorporate the experimentally- observed characteristics of interface layers as input into optical models for the p-i-n solar cell structure. In this way, we demonstrate the beneficial effects of SnO2/p/i interface microroughness as an anti-reflector and the detrimental effects of the ZnO/Ag interlayer as a parasitic absorber.

Type
Research Article
Copyright
Copyright © Materials Research Society 2001

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References

REFERENCES

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