Mass-adoption of thin-film silicon (TF-Si) photovoltaic modules as a renewable energy source can be viable if the cost of electricity production from the module is competitive with conventional energy solutions. Increased module performance (electrical power generated) is an approach to reduce this cost. Progress towards higher conversion efficiencies for 'champion' large area modules paves the way for mass-production module performance to follow. At TEL Solar AG, Trübbach, Switzerland, significant progress in the absolute stabilized module conversion efficiency has been achieved through optimized solar cell design that integrates high-quality amorphous and microcrystalline TF-Si-deposited materials with efficient light management and transparent conductive oxide layers in a tandem MICROMORPH ™ module. This letter reports a world record large area (1.43 m 2 ) stabilized module conversion efficiency of 12.34% certified by the European Solar Test Installation; an increase of more than 1.4% absolute compared with the previous record for a TF-Si triple junction large area module. This breakthrough result generates more than 13.2% stabilized efficiency from each equivalent 1 cm 2 of the active area of the full module.
Novel quaternary Si-B-C-N materials are becoming increasingly attractive because of their possible high-temperature and harsh-environment applications. In the present work, amorphous Si-B-C-N films were deposited on Si and SiC substrates by reactive dc magnetron cosputtering using a single C-Si-B or B 4 C -Si target in nitrogen-argon gas mixtures. A fixed 75% Si fraction in the target erosion areas, a rf induced negative substrate bias voltage of −100 V, a substrate temperature of 350°C, and a total pressure of 0.5 Pa were used in the depositions. The corresponding discharge and deposition characteristics ͑such as the ion-to-film-forming particle flux ratio, ion energy per deposited atom, and deposition rate͒ are presented to understand complex relationships between process parameters and film characteristics. Films deposited under optimized conditions ͑B 4 C -Si target, 50% N 2 +50% Ar gas mixture͒, possessing a composition ͑in at. %͒ Si 32-34 B 9-10 C 2-4 N 49-51 with a low ͑less than 5 at. %͒ total content of hydrogen and oxygen, exhibited extremely high oxidation resistance in air at elevated temperatures ͑even above 1500°C͒. Formation of protective surface layers ͑mainly composed of Si and O͒ was proved by high-resolution transmission electron microscopy, Rutherford backscattering spectrometry, and x-ray diffraction measurements after oxidization. Amorphous structure of the Si-B-C-N films was maintained under the oxidized surface layers after annealing in air up to 1700°C ͑a limit imposed by thermogravimetric analysis in oxidative atmospheres͒.
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