Patent ID: 11876140
Assignee: FIRST SOLAR, INC.
Field: Semiconductors (Electrical engineering)
Classification: CPC H  C  Y | IPC C  H

Claim 0:
1. A photovoltaic device, comprising:
a transparent layer stack;
an absorber layer disposed directly in contact with the layer stack at a front interface of the absorber layer, the absorber layer consisting of a thickness between the front interface of the absorber layer and a back interface of the absorber layer, wherein:
the front interface of the absorber layer is closer to the transparent layer stack than the back interface of the absorber layer,
the absorber layer comprises a compound of cadmium, selenium, and tellurium, an atomic concentration of selenium varies across the thickness of the absorber layer,
the atomic concentration of selenium is greater at the front interface of the absorber layer relative to the back interface of the absorber layer,
a band gap of the absorber layer at the front interface of the absorber layer is lower than the band gap of the absorber layer at the back interface of the absorber layer,
the absorber layer consisting of:
a first region and
a second region, wherein:
the first region extends from the front interface of the absorber layer to the second region,
the second region extends from the first region to the back interface of the absorber layer,
the first region has a continuous uniform thickness between 100 nanometers to 3000 nanometers thick,
the second region has a continuous uniform thickness between 100 nanometers to 3000 nanometers thick, and
a ratio of an average atomic concentration of selenium in the first region to an average atomic concentration of selenium in the second region is greater than 10; and

a p+ type semiconducting layer, wherein:
the absorber layer is between the transparent layer stack and the p+ type semiconducting layer, and
the p+ type semiconducting layer comprises at least one of: zinc telluride, magnesium telluride, manganese telluride, beryllium telluride, mercury telluride, arsenic telluride, antimony telluride, or copper telluride.