Faculté des sciences

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... Plus

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    Summary
    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 relative temperature coefficient of 0.27%/K. Applying the grain-boundary trapping model so far developed for CVD polysilicon to hydrogenated microcrystalline silicon deposited by VHF plasma, an upper limit for the average defect density of around 2 × 1016/cm3 could be deduced; this fact suggests a rather effective hydrogen passivation of the grain-boundaries. First TEM investigations on μc-Si : H p-i-n cells support earlier findings of a pronounced columnar grain structure. Using Ar dilution, deposition rates of up to 9 Å/s for microcrystalline silicon could be achieved.