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27th European Photovoltaic Solar Energy Conference and Exhibition; 1538-1544, In this paper a novel concept of applying a thin transparent Al2O3 layer as a replacement for the intrinsic amorphous hydrogenated silicon (a-Si:H) passivation layer normally used in heterojunction (HJ) solar cells is investigated. This concept has the advantage of a reduced parasitic absorption in the a-Si:H emitter stack. Furthermore, we investigate Al2O3 negative charge field effect passivation compared to a-Si:H surface passivation. In this paper, Al2O3 passivation layers were applied as thin intermediate layers on the illuminated emitter sides of solar cells fabricated on nand p-type Si substrates. We show that the introduction of thin Al2O3 layers leads to the S-shaped current-voltage (IV) curves for all fabricated cells, hence degrading the fill factors and energy conversion efficiencies of the devices. Simulations and experiments lead to the assumption that large energy band offsets at the Al2O3/c-Si interface are presumably the reason for the S-shape formation in the IV-curves.

26th European Photovoltaic Solar Energy Conference and Exhibition; 483-486, In this paper we investigate electrodeposited ZnO nanorods (NRs) on tin doped indium oxide (ITO)-coated glass for solar cells, targeted to incorporate metalorganic dyes, quantum dots or an extra thin absorber layer. The introduction of the NRs into such a cell allows to improve the electron transport and to enhance the light harvesting efficiency, providing at the same time a large three-dimensional interface. The NR morphology is therefore a key issue towards the solar cell development and is highly dependent on the parameters of the fabrication process. We have focused on the influence of the electrodeposition process parameters, namely the applied potential, concentration of solution precursors, deposition temperature and time, on the morphology of the ZnO NRs. It was shown that the aspect ratio of the NRs can be controlled by varying the concentrations of precursors in the solution, whereas their density depends mostly on the applied voltage. The process temperature, on the other hand affects mostly the NR crystallinity. The structural analysis revealed the competing NR growth from the early synthesis stages, giving rise to randomly oriented NRs on ITO.

25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain; 504-507, Light emission-based techniques, such as photo- and electroluminescence (PL, EL), have been demonstrated as excellent tools for developing and monitoring the fabrication of solar cells. In this paper, a PL-based, contactless method is developed to analyze III-V multi-junction solar cells. Characterization of these devices is usually challenging because it is difficult to access information about individual subcells using common measurement techniques. In our method, a tunable laser is employed for carrier photogeneration in individual component junctions and their voltages are measured from a photoluminescence signal. The main advantages of the introduced technique include the possibility of current-voltage (I-V) curve estimation in each of the sub-cells in a multi-junction cell and compatibility with both fully and partially processed solar cells.