Silicon Solar Cell Material Of The Light Trapping And Light Trapping Structure

To decrease the cost of photovoltaic system, the cost of the modules must be firstly decreased. However, the lower cost of package asks the lower the cost of materials. Firstly, how to increase the efficency; secondly, try to thin the thickness of silicon wafer. When the thickness of solar cells are decreased the light loss from transmitance light increase. To the indirect band gap silicon, these light loss are larger than direct band gap materials.The light trapping structure should include below: â‘ the fabrication of antireflection films on the surface of incident light; â‘¡light trapping method should be adopted to enhance light absorption after the light insident, for example, back reflection layer or layers that have lower refraction index be prepared to reflect light back to the absorption layer; â‘¢grids on the front surface should be as few as possible to increase aperture area so as to increase light induced current. Theoretical calculation implied: when material thickness was reduced to 50μm, if high effective light trapping structure which was designed from the optical path calculation was adopted, the light loss caused by decreasing the thickness of the material can be compensated.Presently, the thickness of the solar cells on the world is generally more than 50μm. And the light trapping structure mostly is surface texture and evaporated antireflection film: â‘ for solar cells based on single crystalline silicon wafers, diamond textures were mostly adopted using alkali eroding method; â‘¡for solar cells based on multicrystalline silicon wafers, merely S13N4 antireflection films were always prepared for large area commercially manufacturing. Although 16.8% efficiency had been achieved for rough surface multicrystalline silicon wafer based solar cells, rough surface method were not used for large scale manufacturing. The key to this method was to control the stability and surface contact. â‘¢for silicon thin film solar cells, light trapping method was always textured transparent conductive contact and surface antireflection films.At present, textured SnO₂ transparent conductive glass had been industrialized. But when used as substrate to prepare μc.Si.H thin films in PECVD, it could be deoxidized...