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

High-Ts amorphous top cells for increased top cell currents in micromorph tandem cells

Platz, R. ; Hof, Ch. ; Fischer, Diego ; Meier, Johannes ; Shah, Arvind

In: Solar Energy Materials and Solar Cells, 1998, vol. 53, no. 1-2, p. 1-13

In the present paper, the authors discuss the application of amorphous p–i–n solar cells containing i-layers which are deposited at high substrate temperatures as top cells in amorphous silicon/microcrystalline silicon tandem (“micromorph”) solar cells. Increasing the substrate temperature for the deposition of intrinsic a-Si : H results in a reduced optical gap. The optical absorption is...

Université de Neuchâtel

Correlation between transport properties of a-Si:H layers and cell performances incorporating these layers

Wyrsch, Nicolas ; Beck, N. ; Hof, Ch. ; Goerlitzer, M. ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 1996, vol. 198-200, p. 238-241

Using the new ‘quality parameter’, μ0τ0, the authors were able to show, for the first time, a clear correlation between transport properties of a series of a-Si:H films (grown at various deposition temperatures) and the efficiency of p-i-n cells incorporating the same material as i-layer. In this paper, additional experimental data are presented sustaining, on one...

Université de Neuchâtel

Stability of a-Si:H prepared by hot-wire and glow discharge using H2 dilution evaluated by pulsed laser degradation

Hof, Ch. ; Ziegler, Y. ; Platz, R. ; Wyrsch, Nicolas ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 1998, vol. 227-230, p. 287-291

The quality of intrinsic amorphous silicon films prepared by different deposition techniques was investigated. For very high frequency glow discharge, both the substrate temperature as well as the hydrogen dilution were varied. These layers were compared to hot wire material produced at comparable temperatures. To study the stability of these films, an optimised degradation method was developed...

Université de Neuchâtel

Recent progress in micromorph solar cells

Meier, Johannes ; Dubail, S. ; Cuperus, J. ; Kroll, U. ; Platz, R. ; Torres, Pedro ; Anna Selvan, J. A. ; Pernet, P. ; Beck, N. ; Pellaton Vaucher, N. ; Hof, Ch. ; Fischer, Diego ; Keppner, Herbert ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 1998, vol. 227-230, p. 1250-1256

Recently, we have demonstrated that intrinsic hydrogenated microcrystalline silicon, as deposited by the very high frequency glow-discharge technique, can be used as the active layers of p–i–n solar cells. Our microcrystalline silicon represents a new form of thin film crystalline silicon that can be deposited (in contrast to any other approach found in literature) at substrate temperatures...

Université de Neuchâtel

Influence of electric field distortion and i-layer quality on the collection function of drift-driven a-Si:H solar cells

Hof, Ch. ; Wyrsch, Nicolas ; Shah, Arvind

In: Journal of Non-Crystalline Solids, 2000, vol. 266-269, p. 1114-1118

A refined analytical model describing the photocurrent collection in amorphous silicon solar cells is presented. Thereby, variations of the electric field within the intrinsic layer are formally taken into account and it is shown that they can be summarized in a ‘form factor’, φ, which reduces the effective mobility recombination time product of the interior. Based on this model an...

Université de Neuchâtel

Towards high-efficiency thin-film silicon solar cells with the “micromorph” concept

Meier, Johannes ; Dubail, S. ; Platz, R. ; Torres, Pedro ; Kroll, U. ; Anna Selvan, J. A. ; Pellaton Vaucher, N. ; Hof, Ch. ; Fischer, D. ; Keppner, Herbert ; Flückiger, R. ; Shah, Arvind ; Shklover, V. ; Ufert, K. -D.

In: Solar Energy Materials and Solar Cells, 1997, vol. 49, no. 1-4, p. 35-44

Tandem solar cells with a microcrystalline silicon bottom cell (1 eV gap) and an amorphous-silicon top cell (1.7 eV gap) have recently been introduced by the authors; they were designated as “micromorph” tandem cells. As of now, stabilised efficiencies of 11.2% have been achieved for micromorph tandem cells, whereas a 10.7% cell is confirmed by ISE Freiburg. Micromorph cells show a rather low...

Université de Neuchâtel

Intrinsic microcrystalline silicon (μc-Si:H) deposited by VHF-GD (very high frequency-glow discharge): a new material for photovoltaics and optoelectronics

Shah, Arvind ; Vallat-Sauvain, Evelyne ; Torres, P. ; Meier, Johannes ; Kroll, U. ; Hof, Ch. ; Droz, C. ; Goerlitzer, M. ; Wyrsch, Nicolas ; Vaněček, M.

In: Materials Science and Engineering B, 2000, vol. 69-70, p. 219-226

The development of μc-Si:H technology and the introduction of intrinsic μc-Si:H as photovotaically active material is retraced. Special emphasis is laid on the use of very high frequency glow discharge as a particularly propitious deposition method for μc-Si:H. Thereby, the use of a gas purifier to reduce oxygen content and obtain intrinsic layers with ‘midgap’ character is described....

Université de Neuchâtel

Analysis of the inner collection efficiency in hybrid silicon solar cells

Nubile, P. ; Torres, P. ; Hof, Ch. ; Fischer, D.

In: Solid-State Electronics, 1997, vol. 41, no. 8, p. 1202-1206

The collection of photogenerated carriers in hybrid silicon solar cells structures were determined by the DICE (dynamic inner collection efficiency) technique. The hybrid solar cells have a microcrystalline n-type emitter and a crystalline p-type base. Cells with amorphous buffers of several thickness and p+ back surface field microcrystalline layers were also...

Université de Neuchâtel

Mobility lifetime product—A tool for correlating a-Si:H film properties and solar cell performances

Beck, N. ; Wyrsch, Nicolas ; Hof, Ch. ; Shah, Arvind

In: Journal of Applied Physics, 1996, vol. 79, no. 12, p. 9361-9368

The missing correlation between film characteristics and α-Si:H-based p-i-n solar cells is still a controversial subject. The authors present a new parameter µ0τ0, evaluated from steady-state transport measurements on a-Si:H layers, which can indeed relate film quality and cell performance as far as the latter is limited by the quality...