Photovoltaic devices and method of manufacturing

A photovoltaic device comprising:

• a transparent conductive oxide (TCO) layer;
• a back contact layer;
• and
• an absorber layer between the TCO layer and the back contact layer, wherein:
• the absorber comprises a surface proximate to the TCO layer and a surface proximate to the back contact;
• the absorber layer is p-type;
• the absorber layer comprises a CdSexTe1-x compound, wherein x is less than or equal to 0.30 throughout the absorber layer;
• the absorber layer has a concentration gradient of Se therein, wherein Se is present throughout the absorber layer;
• and
• a peak concentration of Se, of the concentration gradient of Se, is located within the absorber layer and between the surface proximate to the TCO layer and the surface proximate to the back contact;
• wherein:
• a total thickness of the absorber layer is in a range from about 1500 nm to about 4500 nm;
• a value of x proximate to the TCO layer is in a range of about 0.05 to 0.30;
• and
• the value of x is less than 0.01 at a distance from about 800 nm to about 2000 nm away from the TCO layer.

A method of forming a photovoltaic device comprising the steps of:

• depositing a transparent conductive oxide (TCO) layer over a substrate;
• depositing an absorber layer over the TCO layer, wherein the absorber layer comprises cadmium, selenium, and tellurium in a CdSexTe1-x compound, wherein x is less than or equal to 0.30 throughout the absorber layer;
• and wherein:
• a concentration of Se proximate to the TCO layer is higher than a concentration of Se proximate to the back contact;
• a total thickness of the absorber layer is in a range from about 1500 nm to about 4500 nm;
• a value of x proximate to the TCO layer is in a range of about 0.05 to 0.30;
• and
• the value of x is less than 0.01 at a distance from about 800 nm to about 2000 nm away from the TCO layer;
• and
• depositing a back contact over the absorber layer, whereby the absorber layer is between the TCO layer and the back contact.