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HL: Halbleiterphysik

HL 27: Poster II: SiC (1-7), Ultrakurzzeitdynamik (8-15), Halbleiterlaser (16-20), GaN (21-38), III-V Halbleiter (39-56), Photovoltaik (57-64), Störstellen (65-68), Tern
äre Halbleiter (69-70)

HL 27.57: Poster

Mittwoch, 29. März 2000, 14:00–19:00, A

Theoretical Study of Buffer Layer Effect on Open Circuit Voltage in Solar Cells — •Gottfried Heinrich Bauer — Fachbereich Physik, C.v.O. Universität, D-26111 Oldenburg

The open circuit voltage Voc in solar cells can be formulated by

splitting of Quasi-Fermi levels via Boltzmann approximation for

minority carrier concentration in steady state under photo excitation.

Since large absorption coefficients providing large excess minority

densities are accompanied by short distances to regimes with high

recombination velocities as well, such as the light entrance surface,

the introduction of buffer/passivation layers for the prevention of

minority motion towards low life time regimes is a common

approach.

We have theoretically studied and numerically simulated the influence

of 3 types of buffer layers on minorizy darrier concentration that

has been translated into Voc:

- buffer /passivation layers with reduced diffusion length

i) due to drop in life time;

ii) due to decrease in mobility/diffusion constant;

- buffer layers preventing minority diffusion/motion to the surface,

and allowing for undisturbed majority transport.

We discuss our results in terms of departures of Voc in buffered

cells from un-buffered ones and need in chemical potential for

carrier motion accross these regions.