Methods for fabricating thin film solar cells

A method of fabricating solar cells using a continuous roll-to-roll system, wherein continuously moving substrate through the units to deposit back contact electrode, electroplate copper, indium, gallium alloy, and selenium alloy for fabricating CIGS thin film solar cells, comprising steps of:

• depositing a back contact electrode on substrate;
• sequentially electroplating a stack comprising of at least one layer of copper, at least one layer of indium, at least one layer of gallium alloy, and at least one layer of selenium alloy;
• measuring and controlling the thickness of each stack layers
• thermally treatmenting the electroplated stack at a high temperature to form a p-type semiconductor thin film comprising of copper, indium, gallium, selenium, and sulphur;
• depositing a n-type semiconductor layer on the p-type semiconductor layer to form p-n junction
• depositing transparent conductive window layers on the n-type semiconductor layer
• forming front electrodes