Buffer layer of copper-indium-gallium-selenide thin film solar cell chip, preparation method of buffer layer and copper-indium-gallium-selenide thin film solar cell chip

The invention discloses a buffer layer of a copper-indium-gallium-selenide thin film solar cell chip, a preparation method of the buffer layer and the copper-indium-gallium-selenide thin film solar cell chip. The buffer layer is a CdS:O buffer layer; the side, close to an adsorption layer, of the CdS:O buffer layer comprises epitaxial growth CdS; and the side, away from the adsorption layer, of the CdS:O buffer layer comprises nanocrystalline CdS. The nanocrystalline CdS in the buffer layer can effectively prevent Cd from diffusing into the copper-indium-gallium-selenium (CIGS) adsorption layer, the band gap of the CdS can be effectively increased through the introduction of oxygen, the light absorption of the CdS on light is reduced, the battery efficiency is improved, and the buffer layer has a buffering effect and also has an effect of preventing metal diffusion. According to the preparation method, the CdS is easier to grow epitaxially at the interface of the CIGS absorption layer,and CdS nanocrystals are