Amorphous Submicron Layer in Depletion Region: New Approach to Increase the Silicon Solar Cell Efficiency

Abstract

The insertion of a thin amorphized layer (AL) in the space charge region of a silicon solar cell is proposed as a way to improve the conversion efficiency due to the impurity photovoltaic effect. Previously, this approach had been applied to a cell with a layer inserted in the emitter by the ion implantation. The insertion of such layer in the space charge region is founded to be preferable, because a better control over the recombination (via energy levels in the band gap and local states of interfaces) can be achieved. The parameters of a modified device are investigated by the numerical simulation, and it is concluded that the layer parameters have a crucial influence on the cell conversion efficiency. Based on our simulation results, the optimal AL and the height of barriers are determined. In such a case, the short circuit current density is improved due to the absorption of photons with energy less than a silicon band gap of 1.12 eV in AL, whereas the open circuit voltage and fill factor remain unchanged. Theoretically, the increase in the efficiency by 1-2% is achievable. In the non-optimal case, the degradation of a short circuit current and the fill factor eliminate the positive effect of an additional photogeneration in AL.K e y w o r d s: amorphized layer, space charge region, + -silicon solar cell.

Influence of Substrate Type and Dose of Implanted Ions on the Electrical Parameters of Silicon in Terms of Improving the Efficiency of Photovoltaic Cells

“…They are aimed at better understanding and mastering the fundamental phenomena governing photovoltaic conversion and limiting the quantum efficiency of solar cells. The combination of optical spectroscopy and electric transport technology allowed to investigate the physical phenomena responsible for photoconversion [18]. Their main goal is to determine the presence of new phenomena such as impurity photovoltaic effect (IPV) and intermediate band generation (IBSC).…”