Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 79: Photovoltaics: Mainly Silicon

HL 79.3: Talk

Thursday, March 17, 2011, 15:00–15:15, FOE Anorg

Simulation of polycrystalline silicon thin film solar cells - model calibration and sensitivity analysis — •Ana-Maria Teodoreanu, Caspar Leendertz, Tobias Sontheimer, and Bernd Rech — Helmholtz-Zentrum Berlin, Kekuléstr. 5. 12489 Berlin

To gain a better insight into the efficiency-limiting processes in polycrystalline silicon (poly-Si) thin film solar cells, we developed a simulation model for the J-V characteristics and minority carrier lifetime based on experimental results using the numerical 1D simulation program AFORS-HET. The calibration of the model has been achieved through simultaneously fitting the measured dark and light J-V curves of twelve poly-Si thin film minimodules with dissimilar thickness and absorber doping concentration. Effective defect density, capture cross section products of 10…100cm⁻¹ have been determined in the poly-Si absorber by this procedure. Transient photoconductance decay measurements of the poly-Si absorbers have also been conducted in the low injection regime (4.5·10¹⁴cm⁻³). High lifetimes of 100µ s have been found which can be explained within our simulation model by field effect passivation. Furthermore simulations indicate that this field effect leads to a strong injection-dependence of carrier lifetime in the operation range of the solar cell. The sensitivity analysis performed with our calibrated model shows that the defects in the absorber layer are crucial for the cell efficiency. Thus, the improvement of the emitter and back surface field layers becomes important only if the absorber itself is of better quality. Moreover we discuss the optimum absorber thickness subject to different doping levels and absorber defect densities.