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A4.05 - Silicon Heterojunction Solar Cell with Hole Selective MoOx Contact 
April 23, 2014   10:15am - 10:30am

Efficient carrier selective contacts and excellent surface passivation are key to solar cells with high power conversion efficiency. We explore substoichiometric molybdenum trioxide (MoOx, x<3) as a dopant-free, hole-selective contact for silicon solar cells. While MoOx is commonly considered to be a semiconductor with a band gap of 3.3 eV, we demonstrate that MoOx may be considered to behave as a high workfunction metal with a low density of states at the Fermi level originating from the tail of an oxygen vacancy derived defect band located inside the band gap at 2 eV above the valence band maximum. Using a hydrogenated amorphous silicon passivation layer between the oxide and the silicon absorber, we fabricate a silicon heterojunction solar cell with a high open-circuit voltage of 711 mV and a power conversion efficiency of 18.8%. Due to the wide band gap of MoOx, we observe a substantial gain in photocurrent of 1.9 mA/cm2 in the ultraviolet and visible part of the solar spectrum, when compared to a p-type hydrogenated amorphous silicon emitter of a traditional silicon heterojunction cell. Our results emphasize the strong potential for oxides as carrier selective heterojunction partners to inorganic semiconductors.

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Keynote Address
Panel Discussion - Different Approaches to Commercializing Materials Research
Business Challenges to Starting a Materials-Based Company
Fred Kavli Distinguished Lectureship in Nanoscience
Application of In-situ X-ray Absorption, Emission and Powder Diffraction Studies in Nanomaterials Research - From the Design of an In-situ Experiment to Data Analysis