WP1 Plasma chemical etching for c-Si photovoltaics
    WP3 Structuring of TCO layers for TF-Photovoltaics
    WP5 Infection control: Process and Materials studies
    WP7 Energy storage – Process and materials R&D
    WP9 Interface technologies for durable adhesion
    WP11 Cross-cutting equipment development

The main objective is to increase the efficiency of thin film solar cells by introducing tailored 3D nano-structured layers with high light trapping performance, suitable for the next generation of solar cell technology. The aim is to achieve this by deposition of nano-structured TCO (transparent conductive oxide) films, in a stable reproducible process, and by development of a plasma post treatment process for TCO surface nano-texture modification. The objective is to improve the efficiency of thin film photovoltaics by between 10 and 25% (relative, compared to the use of standard TCO), enabling routes to thin-film PV cells with lower Eur/Wp manufacturing costs.

As part of the activities within this Work Package, fluorine-doped tin oxide (SnO2: F) nano-structured TCO films have been deposited by Atmospheric Pressure Chemical Vapour Deposition (AP-CVD) from a range of different precursors and co-reactants. These films have been characterized with respect to their optical properties (light scattering, transmission, absorption) and electrical properties (resistance, carrier concentration, mobility). Solar cells have been produced using these TCOs, and their performance in terms of photo-generated current and efficiency has been compared to commercially available “reference” or standard TCOs.

The main result from the work performed so far is that cells with the best TCO show an efficiency of at least 7% higher than cells on TEC-8 , which is an industrially produced on-line TCO, and that they are comparable to the efficiency of cells deposited on AGC U-type, a widely used off-line TCO. Within this project there is a clear outlook on further improvement of properties towards efficiency of at least 10% higher (relative) than reference TCO.

With respect to development of a plasma post treatment, experimental set-ups for two different atmospheric plasma techniques (plasma nozzle and linear DC arc plasma) have been built. Both have been tested for their ability to modify TCO surfaces. Surface nano-texture modification was successfully demonstrated, as indicated by changes in surface morphology and conductivity measurements.

In order to develop a stable, reproducible process, in-situ spectroscopic monitoring techniques have been developed. Spatial measurements of gaseous product species under the APCVD coating head during deposition of SnO2:F have been successfully demonstrated. A set-up for rapid spatial measurements has been built. It is expected that improved process control will be achieved by integration of monitoring techniques in production of nano-textured TCO.