Leland Stanford Junior University

Electric Power Research Institute Incorporated

Sunpower Corporation

Ronald A Sinton

Richard M Swanson

Pierre J Verlinden

A silicon solar cell has increased efficiency by providing an anti-reflection and passivation layer comprising a layer of silicon dioxide thermally grown on a surface of a silicon body and a layer of titanium dioxide deposited on the layer of silicon oxide. In fabricating the composite anti-reflection passivation layer, a layer of aluminum is first deposited on a surface of the thermally grown silicon oxide. After annealing the aluminum layer, the aluminum is removed from the silicon dioxide layer, and the layer of titanium dioxide is then deposited on the surface of the silicon dioxide from which the aluminum was removed. A layer of magnesium fluoride can be deposited on the surface of the titanium dioxide.

Method of making a solar cell having improved anti-reflection

Series connected cells of a solar array formed in a monolithic semiconductor substrate are electrically isolated by forming grooves in a first major surface partially through the substrate between cells and then fracturing the substrate from the bottom of the grooves to an opposing major surface. Metallization interconnecting the cells provides physical integrity of the cell array after the fracturing of the substrate. The grooves can be formed prior to completion of fabrication of the cells or after fabrication of the cells. In an array embodiment where each cell extends from one major surface to the opposing major surface, the grooves can be formed in both major surfaces.

Monolithic series-connected solar cells having improved cell isolation

A high efficiency back side contact solar cell is fabricated using a self-aligning process that reduces the number of masks and alignments as compared with prior processes. The back surface of the cell is patterned by etching into an array of bilevel, interdigitated mesas and trenches, separated by inclined surfaces. Doping of the back surface region produces laterally alternating and overlapping P and N regions associated with the mesas and trenches. A metalization layer is deposited over the entire back side of the cell. The portions of the metalization on the inclined surfaces are readily removed by etching. Removal of the metalization on the inclines surfaces separates the mesa conductors from the trench conductors, leaving a well defined interdigitated array of positive electrodes and negative electrodes.

Bilevel contact solar cells

A photovoltaic converter includes a photovoltaic cell and an enclosure around the cell with a reflective inner surface that reflects light to the cell. An aperture through the wall of the enclosure has a size smaller than the size of the photovaltaic cell. Light enters the enclosure through the aperture and falls upon the cell. Some light is reflected or not absorbed by the cell. This light is re-reflected back to the cell by the reflective inner surface of the enclosure. The small size of the aperture minimizes the escape of reflected light back out of the enclosure.

Growing community of inventors

Palo Alto, CA, United States of America

Ronald A Sinton