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

Département fédéral de l’environnement,
des transports, de l’énergie et de la communication DETEC
Office fédéral de l’énergie OFEN
NEW PROCESSES AND DEVICE
STRUCTURES FOR THE FABRICATION
OF HIGH EFFICIENCY THIN FILM SILICON
PHOTOVOLTAIC MODULES
Annual Report 2008
Author and Co-Authors C. Ballif, A. Feltrin, F. Sculatti-Meillaud, S. Fay, F.J. Haug,
V. Terrazzoni-Daudrix, R. Theron, R. Tscharner
Institution / Company Institute of Microtechnology / University of Neuchâtel
Address Rue A.L. Breguet 2, 2000 Neuchâtel
Telephone, E-mail, Homepage +41 32 718 33 30, +41 32 718 32 01, christophe.ballif@epfl.ch
http://www.unine.ch/pv
Project- / Contract Number OFEN 101191 / 153032
Duration of the Project (from – to) 1.12.2007 - 31.12.2011
Date 10.12.2008
ABSTRACT
The global project goal is to allow for a lowering of the cost of solar electricity based on thin film silicon.
In particular, this “technology push” project aims at developing the processes and device structure
for the future generation of thin film silicon modules, based on amorphous Si or SiGe alloys, and
microcrystalline silicon. The major project axes consider work on layers with new or better properties
(e.g. new materials with higher transparency), on improved processes (more stable, faster processes,
yielding higher quality layers, with potential lower production costs), on enhanced cells and modules
reliability, leading to increased device and module efficiencies while ensuring low costs and reliability.
The key results of this first year of the project can be summarised as follow:
� Intermediate reflector based on SiOx materials with low refractive index (n=1.7) were realised
and could be introduced in high efficiency micromorph cells (13.1% initial efficiency on 1 cm 2 ).
� Cells with ZnO deposited in chemical vapour phase (CVD) could be made virtually stable to
damp heat (85°, 85% humidity) without encapsulation.
� Microcrystalline cells with efficiency >7.1% could be fabricated in large areas reactor with deposition
rates as high as 1 nm/s.
� New asymmetric intermediate reflectors were designed and implemented in n-i-p micromorph
cells compatible with cells on plastic design. Stabilised efficiency of 10.1% could be achieved.
� Processes for high efficiency tandems a-Si/a-Si on glass were developed and stabilised efficiency
of 8.3% could be reached.
� All key steps for embedding of IMT’s cells and modules were tested and characterised.
Finally an important effort was made in terms of equipment and infrastructure upgrade, with the design
and/or acquisition of new state-of-the-art research tools (cluster PECVD systems, sputtering,
lasering, ellipsometry). These tools will be used in the next part of the project.
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