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Université de Neuchâtel

Photovoltaic Technology : The Case for Thin-Film Solar Cells

Shah, Arvind ; Torres, Pedro ; Tscharner, Reto ; Wyrsch, Nicolas ; Keppner, Herbert

In: Science, 1999, vol. 285, no. 5428, p. 692-698

The advantages and limitations of photovoltaic solar modules for energy generation are reviewed with their operation principles and physical efficiency limits. Although the main materials currently used or investigated and the associated fabrication technologies are individually described, emphasis is on silicon-based solar cells. Wafer-based crystalline silicon solar modules dominate in terms of...

Université de Neuchâtel

Scope of VHF plasma deposition for thin-film silicon solar cells

Keppner, Herbert ; Kroll, U. ; Torres, Pedro ; Meier, Johannes ; Fischer, Diego ; Goetz, M. ; Tscharner, R. ; Shah, Arvind

In: Conference Record of the 25th IEEE Photovoltaic Specialists Conference, 1996, p. 669-672

The world-wide attempts in obtaining thin-film crystalline silicon are reviewed. Based on literature published so far, it appears that high-temperature manufacturing steps seem to be unavoidable for obtaining high conversion efficiencies of crystalline silicon based solar cells. High process temperatures are in contradiction for the use of low-cost substrates like e.g. glass or aluminium. Such...

Université de Neuchâtel

Long term behaviour of passively heated or cooled a-Si:H modules

Hof, Ch. ; Lüdi, M. ; Goetz, M. ; Fischer, Diego ; Shah, Arvind

In: Conference Record of the 25th IEEE Photovoltaic Specialists Conference, 1996, p. 1057-1060

We compare the outdoor performance of single junction a-Si:H PV-modules which were mounted in three different ways. One was thermally well isolated against convection and radiation losses in order to reach maximum operating temperatures. A second one was fixed onto a radiator to keep its temperature as close as possible to the air temperature. A third one served as a reference and was mounted...

Université de Neuchâtel

Amorphous silicon solar cells with graded low-level doped i-layerscharacterised by bifacial measurements

Fischer, Diego ; Wyrsch, Nicolas ; Fortmann, C.M. ; Shah, Arvind

In: Conference Record of the 23th IEEE Photovoltaic Specialists Conference, 1993, p. 878-884

Bifacial spectral response characterization of solar cells under near operating condition illumination is used in conjuncture with a novel bifacial DICE analysis to establish the collection efficiency as a function of i-layer position in p-i-n amorphous silicon solar cells. A significant portion of solar cell degradation can be explained in terms of electric field distortions which increase...

Université de Neuchâtel

Preparation of undoped and doped microcrystalline silicon(μc-Si:H) by VHF-GD for p-i-n solar cells

Flückiger, R. ; Meier, Johannes ; Keppner, Herbert ; Goetz, M. ; Shah, Arvind

In: Conference Record of the 23th IEEE Photovoltaic Specialists Conference, 1993, p. 839-844

The electronic transport properties of μc-Si:H materials were investigated. The μc-Si:H was deposited by the very high frequency-glow discharge (VHF-GD) technique at an RF-excitation of 70 MHz. Very thin

doped layers (100-400 Å) were studied. Conductivities higher than 10-3 (Ω cm)-1 could be achieved for films thicker than 150 Å. The as-deposited μc-Si:H is a slightly...

Université de Neuchâtel

Measurement of ambipolar mobility-lifetime product and itssignificance for amorphous silicon cells

Sauvain, E. ; Shah, Arvind ; Hubin, J.

In: Conference Record of the 21th IEEE Photovoltaic Specialists Conference, 1990, vol. 2, p. 1560-1563

In order to evaluate correctly the ambipolar diffusion length (Lamb) or the ambipolar drift length (Le) from a steady-state photocarrier grating (SSPG) diffusion or drift measurement, the condition of charge quasi-neutrality has to be maintained everywhere in the material (ambipolarity condition). This is shown theoretically by calculating the experimentally accessible...

Université de Neuchâtel

a-Si:H films deposited at high rates in a 'VHF' silane plasma: potential for low-cost solar cells

Shah, Arvind ; Sauvain, E. ; Wyrsch, Nicolas ; Curtins, H. ; Leutz, B. ; Shen, D. S. ; Chu, V. ; Wagner, S. ; Schade, H. ; Chao, H. W. A.

In: Conference Record of the Twentieth IEEE Photovoltaic Specialists Conference, 1988, vol. 1, p. 282-287

The very-high-frequency glow discharge (VHF-GD) is a high-rate deposition method for amorphous silicon based on the use of plasma excitation frequencies in the range 30-150 MHz. Thereby the high-energy tail of the electron energy density function is enhanced, increasing the deposition rate R, without a corresponding increase in electric field and ion bombardment. Here, an extensive set of...

Université de Neuchâtel

High-rate deposition of hydrogenated amorphous silicon by the VHF-GD method

Curtins, H. ; Favre, M. ; Wyrsch, Nicolas ; Brechet M. ; Prasad K. ; Shah, Arvind

In: Proceedings of the 19th IEEE Photovoltaic Specialists Conference, 1987, p. 695-698

Université de Neuchâtel

Monitoring a-Si:H solar cells degradation by two sides blue lightcollection

Masini, G. ; Fischer, Diego ; Hubin, J. ; Palma, F. ; Shah, Arvind

In: Conference Record of the Twenty Fourth IEEE Photovoltaic Specialists Conference (1994 IEEE First World Conference on Photovoltaic Energy Conversion), 1994, vol. 1, p. 610-613

In view of the persistent lack of correlation between single layer material properties and solar cell performance, one is at present interested in experimental techniques which allow the characterisation of material properties within a full p-i-n cell. In this paper, the authors introduce a novel method to monitor i-layer properties during degradation of a-Si:H p-i-n solar cell. Two blue,...

Université de Neuchâtel

Intrinsic microcrystalline silicon (μc-Si:H)-a promising newthin film solar cell material

Meier, Johannes ; Dubail, S. ; Flückiger, R. ; Fischer, Diego ; Keppner, Herbert ; Shah, Arvind

In: Conference Record of the Twenty Fourth IEEE Photovoltaic Specialists Conference (1994 IEEE First World Conference on Photovoltaic Energy Conversion), 1994, vol. 1, p. 409-412

“Compensated” microcrystalline silicon is obtained by adding 8-20 ppm diborane in the plasma gas phase. p-i-n cells with such i-layers have increased infrared sensitivity when compared to a-Si:H p-i-n cells. The preparation of the world's first “mixed stacked” a-Si:H/μc-Si:H tandem cell with an initial efficiency of 9.1% is reported. The μc-Si:H cells showed no degradation of the cell...