Energy Conversion Devices, Inc.

David Adler

Stanford R Ovshinsky

Chi C Yang

Arun Madan

The production of improved multiple cell photovoltaic amorphous silicon devices having improved wavelength threshold characteristics is made possible by adding one or more band gap adjusting elements to the silicon alloy material in one or more cells of the device. The adjusting element or elements are added at least to the active photoresponsive regions of constituent amorphous silicon cells, which regions preferably further include at least one of fluorine and hydrogen. One adjusting element is germanium which narrows the band gap from that of the silicon alloy materials without the adjusting element incorporated thereinto. Other adjusting elements can be used, such as carbon or nitrogen to widen the band gap. The silicon and adjusting elements are concurrently combined and deposited as amorphous silicon alloys by glow discharge decomposition techniques.

Multiple cell photoresponsive amorphous photo voltaic devices including

The production of improved multiple cell photoresponsive amorphous devices, such as photovoltaic, photoreceptive devices and the like; having improved wavelength threshold characteristics is made possible by adding one or more band gap adjusting elements to the alloys in one or more cells of the device. The adjusting element or elements are added at least to the active photoresponsive regions of amorphous cells containing silicon and fluorine, and preferably hydrogen. One adjusting element is germanium which narrows the band gap from that of the materials without the adjusting element incorporated therein. Other adjusting elements can be used such as carbon or nitrogen to increase the band gap. The silicon and adjusting elements are concurrently combined and deposited as amorphous alloys by vapor deposition, sputtering or glow discharge decomposition. The addition of fluorine bonding and electronegativity to the cell alloy acts as a compensating or altering element to reduce the density of states in the energy gap thereof. The fluorine bond strength allows the adjusting element(s) to be added to the alloy cells to adjust the band gap without reducing the electronic qualities of the cell alloy. Hydrogen also acts as a compensating or altering element to compliment fluorine when utilized therewith. The compensating or altering element(s) can be added to the alloy during deposition of the cells or following deposition. The addition of the adjusting element(s) to the cell alloys adjusts the band gap to a selected optimum wavelength threshold for particular cells to increase the photoabsorption efficiency to enhance the device photoresponsive without adding states in the gap of the cells which decrease the efficiency of the devices. The adjusting element(s) can be added in varying amounts, in discrete layers or in substantially constant amounts in the cell alloys.

Multiple cell photoresponsive amorphous alloys and devices

The disclosure is directed to photovoltaic devices having enhanced short circuit currents and efficiencies. The devices are made by depositing on a previously deposited doped amorphous semiconductor alloy layer a body of intrinsic amorphous semiconductor alloys including a first intrinsic layer, adjacent the doped layer, formed from the deposition of a non-etching starting material and a second intrinsic layer different in composition from the first intrinsic layer. The second intrinsic layer preferably includes silicon and fluorine while the first intrinsic amorphous alloy layer does not include fluorine. The first intrinsic layer may be formed by the glow discharge decomposition of silane gas alone. The thicknesses of the first and second intrinsic layers are adjusted so as to match the respective potential drops thereof with the first intrinsic layer being relatively thin as compared to the second intrinsic layer.

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Lexington, MA, United States of America

David Adler