VIDI project - Arno Smets
Innovative plasma processing of second and third generation photovoltaic materials
Subsidy: NWO-STW
Duration: 2010 – 2015
Post-doctoral researchers: T. Temple, R. Santbergen
The aim of the VIDI project is to work on a novel solar cell concept consisting of a (micro-) crystalline single junction silicon solar cell combined with a spectrum down converting top film. A film, with a densely packed ensemble of size distributed silicon nanocrystals (NCs), exhibiting the space-separation-quantum-cutting (SSQC) effect, is proposed as an efficient down-converter of the blue part of the solar spectrum. This novel concept basically provides a solution to resolve the outstanding issues of amorphous silicon (a-Si:H)/micro-crystalline silicon (μc-Si:H) tandem solar cells which inhibit high conversion efficiencies and cost effective manufacturing:
a) the instability of the a-Si:H top cell under light exposure,
b) a suboptimal open circuit voltage (Voc ) of the μc-Si:H bottom solar cell and
c) a suboptimal red response and a solar spectrum mismatch in the UV-blue region.
Innovative materials processing approaches of second and third generation photovoltaic materials will be pursued to achieve the aim of the VIDI project. By means of a novel plasma processing approach, the crucial requirements for high SSQC conversion efficiencies (approaching 200%), such as a high packing density of silicon NCs, with an optimum NC size distribution and a high quality passivation of NC surfaces will be met. Moreover, by carefully controlling the plasma process during the growth of μc-Si:H solar cells, the Voc will be increased, by growing larger crystalline grain sizes in the μc-Si:H bulk, by improving the passivation of grain boundaries and by decreasing the number of defects at the doped-intrinsic (p-i) interface. In addition, we will explore deposition technologies to include the plasmon resonance effects at metal particles in the transparent contacts of the μc-Si:H solar cell, which will result in an enhanced absorption of the red part of the solar spectrum.
