Kenichi Okada

Production technology of large-area multicrystalline silicon solar cells

Abstract In 1996 a conversion efficiency of 17.1% had been obtained on 15xa0cm×15xa0cm mc-Si solar cell. In this paper, large-scale production technology of the high-efficiency processing will be discussed. Enlarging reactive ion etching (RIE) equipment size, technology of passivation, and fine contact grid with low resistance by screenprinted metallization, which is firing through PECVD SiN, have been investigated.

Surface and bulk-passivated large area multicrystalline silicon solar cells

Abstract We have investigated the surface and bulk passivation technique on large-area multicrystalline silicon solar cells, a large open-circuit voltage has been obtained for cells oxidized to passivate the surface and hydrogen annealed after deposition of silicon nitride film on both surfaces by plasma CVD method (Pue5f8SiN) to passivate the bulk. The texture surface like pyramid structure on multicrystalline silicon surface has been obtained uniformly using reactive ion etching (RIE) method. Combining these RIE method and passivation schemes, the conversion efficiency of 17.1% is obtained on 15 cm × 15 cm multicrystalline silicon solar cell. Phosphorus diffusion, BSF formation, passivation technique and contact metallization for low-cost process sequence are also described in this paper.

15 cm*15 cm high efficiency multicrystalline silicon solar cell

A large-area multicrystalline silicon solar cell with 15 cm*15 cm cell area using a substrate made by a casting method has been developed to obtain high efficiency at low cost. The bifacial silicon nitride solar cell (BSNSC) fabrication process has been applied to this large-area solar cell. By optimizing the surface structure to reduce the reflective losses, the p-n junction formation and the electrode pattern, conversion efficiencies of 15.6% and 15.3% (AM 1.5, global, 100 mW/cm/sup 2/, 25 degrees C) for large-area multicrystalline silicon solar cells have been obtained by an evaporation method and a screen-printing method, respectively.<<ETX>>

Large-area high efficiency single crystalline silicon solar cells

Abstract This paper reports on a 100 cm 2 single crystalline silicon solar cell with a conversion efficiency of 19.44% ( J sc = 37.65 mA/cm 2 , V oc = 638 mV, FF = 0.809). The cell structure is as simple as only applying the textured surface, oxide passivation, and back surface field by the screen printing method. The comparison between cell performances of the CZ (Czochralski) and FZ (Floating zone) silicon substrates was investigated. The higher efficiency cells were obtained for the FZ substrate rather than the CZ substrate. The influence of the phosphorus concentration of the emitter on the cell efficiency has also been investigated. A good result was obtained when the surface concentration of phosphorus was 3 × 10 20 cm −3 and the junction depth was about 0.6 μm.

Over 16% efficiency large area-multicrystalline silicon solar cell

Since 1989, Kyocera has been carrying out research into high efficiency solar cells using multicrystalline silicon substrates (15 cm/spl times/15 cm) made by the Sumitomo Sitix Co. Ltd. The bifacial Silicon nitride solar cell (BSNSC) fabrication process developed by Kyocera has been applied to this large area solar cell. A conversion efficiency of 16.4% (global AM 1.5, 100 mW/cm/sup 2/, 25/spl deg/C) for the 15 cm/spl times/15 cm multicrystalline silicon solar cell has been obtained by optimizing the front surface structure to reduce the reflective losses, and by improving the front electrode pattern using an evaporation method.<<ETX>>