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29th European Photovoltaic Solar Energy Conference and Exhibition; 1448-1451, We present the latest process in the performance improvement of pin-type a-Si:H/a-SiGe:H/μc-Si:H triple junction solar cell and corresponding single junction solar cells in this paper. Based on the wet-etched sputtering ZnO:Al substrate with optimized surface morphology and photo-electrical material properties, after adjusting individual single junction solar cells which would be utilized in triple junction solar cells with different optimization techniques, we pay close attention to the optimization of tunnel recombination junctions (TRJs). By means of the optimization of individual a-Si:H/a-SiGe:H and a-SiGe:H/μc-Si:H tandem solar cell, we compensated the Voc loss at a-Si:H/a-SiGe:H TRJ resulting from a high p type μc-Si:H activation energy. Combining the optimized single junction solar cells and top/middle, middle/bottom TRJs with little electrical losses, an initial efficiency of over 16% was achieved for pin-type a-Si:H/a-SiGe:H/μc-Si:H triple junction solar cell.

27th European Photovoltaic Solar Energy Conference and Exhibition; 2140-2142, The main purposes are to obtain natively textured surface ZnO-based transparent conductive oxide (TCO) layers for thin film solar cells. Natively textured surface hydrogenated Ga-doped ZnO (HGZO) thin films have been directly deposited without any surface treatment on glass substrates via pulsed direct-current (DC) magnetron sputtering at the substrate temperature of 573 K. The influences of W-doped In2O3 (IWO) buffer layers on the microstructure, electrical and optical performances of HGZO thin films have been investigated. The experiments indicate that the IWO buffer layer can effectively improve the surface roughness of HGZO thin films and enhance the light scattering ability of HGZO thin films. The haze values at 550 nm wavelength increases from 7.05% of HGZO thin film to 18.37% of IWO/HGZO thin film. Through the optimization of process conditions, the IWO/HGZO thin film with 10 nm-IWO buffer layer exhibits high optical transmittance of ~82.18% in the visible and near infra-red region (~400-1100 nm), excellent electrical properties with a relative low sheet resistance of ~3.6Ω/ and as a high haze value of 18.37% at the wavelength of 550 nm. Such an in situ texturing method for sputtered ZnO-TCO thin films has advantages of efficiently reducing production costs and dramatically saving time in photovoltaic (PV) industrial processing.

23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 2297-2300, We studied the boron contamination at the interface between the p and i layers of μc-Si:H solar cells deposited in a single-chamber PECVD system. The boron depth profile in the i layer was measured by Secondary Ion Mass Spectroscopy. We founded that the mixed-phase μc-Si:H materials with 40% crystalline volume fraction is easy to be affected by the residual boron in the reactor. The experimental results showed that both a 500-nm thick μc-Si:H covering layer and a 30 seconds of hydrogen plasma treatment can effectively reduce the boron contamination at the p/i interface. However, from cost reduction point of view, the hydrogen plasma treatment is desirable for solar cell manufacture because the substrate is not moved during the hydrogen plasma treatment.