Development of flexible Cu(In, Ga)Se{sub}2 solar cells on polymers with lift-off processes

摘要

The choice of an appropriate substrate is very important for the development of lightweight and flexible Cu(In,Ga)Se{sub}2 (called CIGS) solar cells. Because of high CIGS deposition temperatures the choice of polymer substrates is restricted to polyimides. We have developed a process where high temperature stable polyimides with tailored thermo-physical properties can be used. Using a NaCl buffer layer and a lift-off process 12.8% efficiency CIGS solar cells have been grown on a 20 μm thin polyimide film. In another approach the CIGS cells are grown at > 500°C on a glass substrate covered with a buffer layer. A transparent polymer is applied after growth of the solar cell and the buffer layer is subsequently dissolved. 8% efficiency solar cells have been obtained.