EFFICIENCY IMPROVEMENT OF POLYCRYSTALLINE SILICON SOLAR CELLS

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Preparation of silcon films for solar cells; Preparation conditions of silicon thin films by the method of melt quenching were experimentally clarified especially on the relation of film dimentions and preparation parameters. These parameters were ejection pressure, atmospheric pressure, disc rotation speed, preparation speed, disc materials and atmospheric gases. Hydrodynamic analysis well interpreted these experimental results quntitatively.Electronic density of states at grain boundaries; The electronic conductivities and temperature dependence of Hall mobilities were measured on the undoped and intentionally boron and phosphorus doped samples. Double schottky barrier model which made double depletion layers at grain boundaties and works as sink for the photogenerated carries and reduce the collection efficiency. Field dependent conductivites under DC bias voltage were well interpreted qualitatively as the carrier transport through the thermionic emission across over the grain boundaries potential barriers.Grain boundaries electric field observation technique; A new method to analize electrically active grain boundaries of polycrystalline silicon by using a field effect of nematic liquid crystal with positive dielectric anisotropy is developed.Plasma passivation of grain boundaries were experimentally recognized.