Thin film solar cells on the basis of CuInSe2 and related chalcopyrite (CIS) are the most promising options for low cost photovoltaics because they could combine high efficiency with low cost processes. World leading submodule efficiencies of close to 14% on 10x10cm2 substrates have been achieved by members of the consortium (ZSW/IPE). The general objective is to demonstrate technically the manufacturability of large area CIS based solar cell modules. The basis for the work is the successful development of coevaporation processes in the previous EUROCIS project which made the European effort world leading in this technology.
The extrapolations for the upscaling of processes made in the APAS project MusicFM will be critically evaluated. All technological steps and solutions for possible problems/bottlenesck will be investigated. New solutions will be experimentally tested and eventually implemented.
Improved process technologies will be finally demonstrated on 30x30 cm2 module area. The goal is an aperture area efficiency of 12% on 30x30cm2 substrates and 14% for small modules on 10x10 cm2 area. These values exceed the presently achieved performance by one percent unit.
Scientific and technical objectives are to:
- identify, with the input of the MusicFM study, the bottlenecks of the state of the art technology of all process steps with respect to: throughput, deposition speed, yield and material usage
- evaluate new and improved materials and processes.
- introduce process improvements to finally eliminate the bottlenecks identified.
- address environmental issues.
The work contains a comprehensive analysis and assessment of all process steps with respect to yield (material and process), throughput, cycle time and environmental impact. This analysis will be based on experimental work so that reliable data are obtained. Furthermore experiments are directed towards new issues for fabrication processes and device design. The most important items of the work are in particular:
- control of substrate quality and impurity diffusion
- semiconductor deposition for absorber films: detailed studies on limitation of deposition speed for coevaporation of absorber films with respe to basic (thermodynamic and reaction kinetics) and process related issues. - Junction and heterointerface: Thermodynamic stability, buffer layer materials and process optimisation, replacement of the Cd containing buffer layer by a novel junction formation technique.
- ZnO sputtering and ALE processes: interaction with heterointerface, electrical/optical figure of merit, throughput.
- Module technology: Laser scribing, new interconnects schemes, electrical connects and encapsulation.
- Devices: increase of the open circuit voltage of the single cell to 800 mV and at the same time achieving 16 % efficiency. This step makes module design (interconnects and thickness of conductive films) less critical. For each process step a clear description of throughput, yield and tolerances of each process step will be made. Alternative solutions will be worked out. A reassessment of module production costs will be carried out at the end of the project. Final goal is to demonstrate a manufacturing process for 30x30 cm2 module with an aperture area efficiency of 12% which complies with the requirements for upscaling at a low cost level.
Funding SchemeCSC - Cost-sharing contracts
164 21 Kista
751 21 Uppsala