Gradient control in thin film solar cells
This project aims at the development of annealing processes in sulfur, selenium or other vapours, for higher efficiency thin film solar cells based on Cu(In,Ga)Se2 and Cu2ZnSnS4. The specific aim is to make band gap graded films both at the back- and front interfaces for reduced solar cell losses. The starting material can be either graded or non-graded and is deposited by co-sputtering or co-evaporation. A custom-built furnace, with three sources, where temperature and partial pressure can be separately controlled, is used. The third source can for example be used for sodium- or potassium-based compounds for surface modifications. The process development, including fabrication, analysis and modelling of solar cell devices, is accompanied by fundamental studies of inter-diffusion, phase segregation, homogeneity and grain growth in these material systems. Large area depth profiling measurements are complemented by local characterization by atom probe tomography. Theoretical analysis by first-principles based methods is used to study properties such as phase stability, electronic structure, defect and cluster formation and grain boundary properties. Diffusion studies are supported by molecular dynamics simulations. The expected outcome is processes for increased device efficiency for these solar cells, or maintained efficiency with processes better suited for industrial processing. This is based on better understanding of fundamental limitations set by thermodynamic and kinetic concerns.
The project is led by Uppsala University's Institute for Engineering Sciences (organisation number 202100-29362; Ångström Laboratory, Lägerhyddsvägen 1, Box 534, SE-751 21, Uppsala, Sweden).
Funding agency
Swedish Foundation for Strategic Research
Beginning and end dates
1 July 2016 - 30 June 2022
Contact person
