CuInSe2 film growth using precursors deposited at low temperature

A sequential deposition process for CuInSe2 leading to highly efficient thin film solar cells is described. Secondary phases and interdiffusion determine the growth mechanism of a process consisting of InSex and Cu deposition at a low substrate temperature followed by a high temperature selenization step. A model which clearly shows the difference between Cu-rich and Cu-poor growth is described. It is shown that sodium is mainly incorporated at the grain boundaries. Devices based on absorber layers produced by the new process exhibit efficiencies close to 14% for CuInSe2.