Absorber layer for a thin film photovoltaic device with a double-graded band gap
AssigneeIntermolecular, Inc.
InventorHaifan Liang
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Abstract
A gallium-containing alloy is formed on the light-receiving surface of a CIGS absorber layer, and, in conjunction with a subsequent selenization or anneal process, is converted to a gallium-rich region at the light-receiving surface of the CIGS absorber layer. A second gallium-rich region is formed at the back contact surface of the CIGS absorber layer during selenization, so that the CIGS absorber layer has a double-graded gallium concentration that increases toward the light-receiving surface and toward the back contact surface of the CIGS absorber layer. The double-graded gallium concentration advantageously produces a double-graded bandgap profile for the CIGS absorber layer.
Claims13
A method of forming a thin-film solar cell absorber layer, the absorber layer having a first surface that is light receiving, the method comprising:
- forming a first layer on a substrate, wherein the first layer comprises copper, indium, gallium, and selenium and includes a gallium-rich region;
- forming a second layer above the first layer via thermal pyrolysis of trimethyl gallium (TMGa), wherein the second layer comprises gallium;
- and
- exposing the second layer to heat and a selenium-containing gas to convert the second layer to a third layer that comprises gallium and selenium.
A method of forming a thin-film solar cell absorber layer, the absorber layer having a first surface that is light receiving, the method comprising:
- forming a first layer on a substrate, wherein the first layer comprises copper, indium, gallium, and selenium and includes a gallium-rich region;
- forming a second layer above the first layer via thermal pyrolysis of trimethyl gallium (TMGa), wherein the second layer comprises gallium;
- exposing the second layer to heat and a selenium-containing gas to convert the second layer to a third layer that comprises gallium and selenium;
- and
- heating the third layer to convert the third layer to a gallium rich region at the light receiving surface of the absorber layer.
Dependencies are inferred from the claim text.