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Poster Award EUPVSEC 2014

The contribution entitled ‘Efficiency Enhancement in Tandem Thin-Film Silicon Solar Cells by Industrial Light Management Concepts’ received the poster award in the section ‘Thin Film Solar Cells’ at the ‘29. European Photovoltaic Solar Energy Conference and Exhibition (EUPVSEC)’ (, held in September 2014 in Amsterdam. On the poster and in the corresponding paper results were presented, which were achieved in the EU-project ‘Fast Track’ ( Therein the effect of industrially relevant measures for a better light exploitation in tandem solar cells was investigated. This type of solar cell is designed as a stack of an amorphous (a-Si:H) and microcrystalline (µc-Si:H) silicon solar cell. For reference tandem solar cells with a standard-textured front contact of etched zinc oxide (ZnO) were employed, which achieved a maximum power conversion efficiency (under AM1.5 solar illumination) of 11.7%. A comparison of the respective solar cells with the highest conversion efficiencies showed the following results:

a)      Antireflection coating at the front glass by means of SiOx particles in a silicon matrix fabricated via APCVD by the company CVD Technologies Ltd. ( in Salford (UK): Efficiency increase to 12.0%.

b)      Periodic grating structure at the front side between glass and ZnO - front contact fabricated via nanoimprint technology by the company OM&T B.V. in Eindhoven (Netherlands): Efficiency gain to 12.1%.

In both cases the efficiency enhancement of the solar cells relies on the improvement of their short-circuit current Isc. In case a) this rise is achieved by a wavelength independent reduction of the reflectance over the whole wavelength range of the AM1.5 solar spectrum  relevant for this type of solar cells (300 nm to 1100 nm). In case b) the Isc gain is mainly achieved in the long wavelength range  due to a better light-trapping obtained by the periodic grating structure at the front side.