Improved CdS buffer/window layers for thin film solar cells

Abstract A dip method to fine tune the absorbance of CdS thin polycrystalline films using the size-dependent band gap of this semiconductor is presented. The method consists of preparing pure and anisotropically capped CdS nanocrystals in an organic solvent. These particles have the property to self-connect on solid surfaces, leading to a textured homogeneous coating. The film can be converted thermally into a pure CdS film. The band gap of the thin film can be fine tuned through the size of the particle precursor or by controlling the conversion temperature during the capping ligand thermolysis. These films should provide a good buffer-window layer for thin film solar cells. In fact, the optical cut-off can be adjusted to avoid interfering with light collection. These films are compared with others made by classical chemical bath techniques.