Programm Photovoltaik Ausgabe 2009 ... - Bundesamt für Energie BFE

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Effective light trapping schemes were implemented on flexible plastic substrates produced by roll-toroll.
Many other strategies have also been investigated in order to produce higher efficiency single and
tandem cells. In the framework of the project, a focus was done for further development in solar cells
on plastic substrates.
The three most promising techniques for high rate deposition of �c-Si:H material were investigated i.e.
Very High Frequency Plasma Enhanced Chemical Vapour Deposition (VHF-PECVD), Hot Wire
Chemical Vapour Deposition (HWCVD) and Microwave Plasma Enhanced Chemical Vapour Deposition
(MW-PECVD).
A new encapsulation process was developed and led to the certification of the first BIPV product from
VHF-Technologies/Flexcell, according to CE-EN61646 norm.
The production costs for multi-megawatt production lines based on the different techniques mentioned
above were shown to be in-line with the market requirements, i.e. around 0.91 €/Wp for 200MW production
capacity by 2011/2012 and close to 0.5 €/Wp five years later, provided that higher efficiency,
higher deposition rate and more cost-effective material could be achieved.
Finally, significant developments could be made on all necessary steps towards monolithic series interconnection
of flexible thin film silicon modules in n-i-p configuration:
� Water based lift-off structuring and depth selective laser scribing process,
� Screen printing of low-temperature curing Ag and insulating inks,
� Optimization of module layout by simulations.
Some results on water based lift-off process and screen printing of low-temperature curing silver and
insulating inks are already implemented in production at VHF-Technologies.
Most of the results of the Flexcellence project are reported in journal papers and conference proceedings.
An updated list is available at www.unine.ch/flex.
Specific IMT results of the last project year
During this last reporting period, the IMT focused mainly on the development of high efficiency solar
cells on flexible plastic substrates.
The IMT investigated different strategies to increase the solar cell performances at the degraded state.
Particularly, carbide n-doped layers were developed on glass and implemented on nano-textured plastic
substrates so that Jsc up to 14.4 mA/cm 2 could be reached on plastic [1, 2] (see Figure 2).
Fig. 2: External quantum efficiencies of amorphous solar cells on roll-to-roll embossed plastic substrates.
On all textured substrates the current density exceeds 14 mA/cm 2 . The reference substrates
consist of flat silver in combination with flat and textured ZnO, respectively.
Flexcellence, V. Terrazoni, IMT Neuchâtel
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