1. Field of the Invention
This disclosure relates to a method of fabricating a thin film solar cell and an apparatus for fabricating a thin film solar cell.
2. Description of the Related Art
A solar cell converts solar energy into electrical energy. The solar cell, which includes a diode generally having PN junctions, can be classified into various compositional types of solar cell depending upon the composition of the material used to form the light absorbing layer.
A solar cell including a light absorbing layer of silicon may be subclassified as either a crystalline substrate (wafer) solar cell or a thin film (amorphous, polycrystalline) solar cell. In addition, a compound thin film solar cell based on a CIGS (CuInGaSe2) or CdTe material, a Group III-V solar cell, a dye-sensitive solar cell, and an organic solar cell may each be exemplified as representative solar cells.
Of these, the thin film solar cell which includes a light absorbing layer of CIGS or CdTe further includes a buffer layer of CdS between the light absorbing layer and an adjacent electrode, to compensate for a band gap difference and a lattice constant difference. The buffer layer is prepared in accordance with a chemical bath deposition (“CBD”) process. A CBD process may include dissolving, for example, a cadmium (Cd) source material and a sulfur (S) source material in an ammonia solution, immersing a substrate formed to have a light absorbing layer therein to coat the substrate, and heating the coated substrate to provide a buffer layer having a thickness of several tens of nm. However, the CBD process undesirably increases the process cost and causes environmental contamination due to its requirement of large quantities of hazardous chemicals.
USPTO Backgrounds
USPTO Backgrounds