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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Electrical Engineering and Computer Science

First Advisor

Qiquan Qiao

Second Advisor

David Galipeau


DSSCs have attracted much attention in recent years as an alternative to crystalline silicon solar cells because of the low cost and simple fabrication process. Typical DSSCs made from nanocrystalline TiO2 undergo UV-light induced degradation. SnO2 based DSSCs on the other hand can withstand UV-light as it has higher band gap. However, the efficiency of SnO2 based DSSCs is poor. Thus, there is a need for high efficiency dye sensitized solar cell with long term stability. The objective of this research was to improve the efficiency of SnO2 based DSSC to 6%. Photoanodes in DSSCs should have high light harvesting capability, and maximum dye attachment and the devices should have suppressed back charge transfer to the electrolyte. In this work, TiO2 coated urchin like SnO2 microspheres with high light scattering, enhanced dye loading, and suppressed back charge transfer to the electrolyte were studied for the first time in DSSCs. Diffuse reflectance and absorption spectroscopy were used to estimate light scattering and dye loading of photoanodes. Back charge transfer to the electrolyte was studied by EIS and transient photovoltage measurement. Urchin-like SnO2 microspheres showed broad reflection from 300 nm to 800 nm with maximum of 61% at 530 nm suggesting a high light scattering property. TiO2 coated Urchin-like SnO2 microspheres showed enhanced light scattering by 17%, enhanced dye loading by 45%, and suppressed recombination rate of interfacial electrons by 32 times. Coatings of TiO2 on bare urchinlike SnO2 microsphere photoanode led to a fourfold increment in efficiency (from 1.43% to 6.05%). Thus, TiO2 coated urchin-like SnO2 microspheres can provide a promising alternative for TiO2 in DSSCs with long term stability and high-efficiency.

Library of Congress Subject Headings

Dye-sensitized solar cells


Includes bibliographical references (pages 64-74)



Number of Pages



South Dakota State University


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