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Hole Selective MoOx Contact for Junctionless Silicon Solar Cells, LEDs, Photodetectors and Transistors



Junctionless devices used for


Using an ultrathin (~15 nm in thickness) molybdenum oxide (MoOx , x<3) layer as a transparent hole selective contact to n-type silicon, researchers at Berkeley Lab demonstrated a room-temperature processed oxide / silicon solar cell with a power conversion efficiency of 14.3%. While MoOx is commonly considered to be a semiconductor with a band gap of 3.3 eV, from X-ray photoelectron spectroscopy, the researchers showed 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.

Specifically, in the absence of carbon contamination, they measured a work function potential of ~6.6 eV, which is significantly higher than that of all elemental metals. Their results on the archetypical semiconductor silicon demonstrate the use of nm-thick transition metal oxides as a simple and versatile pathway for dopant-free contacts to inorganic semiconductors. This work has important implications toward enabling a novel class of junctionless devices with applications for solar cells, light emitting diodes, photodetectors and transitors.

For more details, see the researchers' publication in NanoLetters, linked below.


Battaglia, C., Yin, X., Zheng, M., Sharp, I.D., Chen, T., McDonnell, S., Azcatl, A., Carraro, C., Ma, B., Maboudian, R., Wallace, R. M., Javey, A. “Hole Selective MoOx Contact for Silicon Solar Cells,” NanoLetters, 2014, 14, 967-971.

STATUS: Patent pending. Available for licensing or collaborative research.


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