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New and more stable a-Si: H based materials for photovoltaics


The project is concerned with enhancing the stability of the intrinsic layer of a-Si:H (Silicon-Hydrogen) based solar cells.

The well-known problem of light degradation of a-Si:H films, will be studied by parallel and interactive examination of the properties of the plasma and the material. The basic idea behind this approach is to optimize the deposition conditions in order to obtain not the lowest defect density in the as-deposited state, but the lowest defect density after light exposure. In this direction the stability problem will be addressed through the study of a-Si:H based materials grown under deposition conditions which differ from today's optimum conditions. In particular the study will include deposition at higher temperatures, at high deposition rates from Silane-Helium mixtures, low-hydrogen content films deposited from SiF4-H2 mixtures, low-gap a-Si, Ge:H films, a-Si:H films deposited under strong ion bombardment, deposition assisted by visible/UV light, in modulated plasma conditions and in very different discharge geometries. Thus it is possible to obtain very different a-Si:H films that have more stable properties. The different plasma conditions will be extensively studied by advanced optical and electrical diagnostics
while film growth will be examined by in-situ elipsometry. The study will include the combination of accelerated light-soaking techniques, the use of recent models to analyze the kinetics of the Staebler-Wronski effect in a-Si:H based materials and p-in-n solar cells, and the full characterization of the deposited films. The combined approach should permit identification of the main material parameters which determine the creation of metastable defects, and by correlation to the plasma parameters the definition of the optimum conditions for the production of the films with the lowest metastable defect density and the highest device
efficiency in the light-soaked state. The optimized conditions will be used for the fabrication of p-in-n solar cells, while the experience gained will be transferred to SOLEMS for the production of modules. The goals of this project include the achievement of an 11% stable 1cm2 solar cell and a 9% stable module.

Call for proposal

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University of Patras
University Campus-rio
26110 Patras

Participants (3)

Route De Saclay Ecole Polytechnique
91128 Palaiseau
Philipps-Universität Marburg
Renthof 5
35037 Marburg
Università degli Studi di Bari
Via Orabona 4
70126 Bari