Stress-induced bandgap-shifted semiconductor photoelectrolytic/photocatalytic/photovoltaic surface and method for making same
OwnerJohn M. Guerrainventor
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Abstract
Titania is a semiconductor and photocatalyst that is also chemically inert. With its bandgap of 3.0, to activate the photocatalytic property of titania requires light of about 390 nm wavelength, which is in the ultra-violet, where sunlight is very low in intensity. A method and devices are disclosed wherein stress is induced and managed in a thin film of titania in order to shift and lower the bandgap energy into the longer wavelengths that are more abundant in sunlight. Applications of this stress-induced bandgap-shifted titania photocatalytic surface include photoelectrolysis for production of hydrogen gas from water, photovoltaics for production of electricity, and photocatalysis for detoxification and disinfection.
Claims14
A photovoltaic cell comprising:
- a light-transmissive substrate having a first surface through which light can enter the substrate and an opposed second surface provided with undulations;
- a light-transmissive electrically conductive layer provided on the second surface of the substrate;
- a stress-induced bandgap shifted semiconductor thin film overlying the light-transmissive electrical conductive layer and capable of absorbing light;
- and
- an electrode layer overlying the semiconductor thin film,
- the undulations having a spatial pitch smaller than the wavelength of the light absorbed by the semiconductor layer, and induce regions of stress of at least about 1 GPa in the semiconductor thin film.
A photovoltaic cell comprising:
- a light-transmissive substrate having a first surface through which light can enter the substrate and an opposed second surface provided with undulations;
- a light-transmissive electrically conductive layer provided on the second surface of the substrate;
- a stress-induced bandgap shifted semiconductor amorphous film overlying the light-transmissive electrical conductive layer and capable of absorbing light, the undulations in the substrate having a spatial pitch smaller than the wavelength of the light absorbed by the semiconductor layer, and induce regions of stress of at least about 1 GPa in the semiconductor thin film sufficient to shift, decrease, and broaden the band-gap in the semiconductor amorphous film;
- and
- an electrode layer overlying the semiconductor amorphous film.
Dependencies are inferred from the claim text.