The invention discloses a
photonic crystal back reflector provided with an adjustable forbidden band and applied to a
silicon-based thin-film
solar cell. The
photonic crystal back reflector is composed of low-
refraction-index media and high-
refraction-index media which are overlapped in a periodic mode. Through adjustment of the thickness of a period, an average
reflectivity of 96% can be obtained in a
wave band of 500-750mm, an average
reflectivity of 99% can be obtained in a
wave band of 650-1100nm, and an average
reflectivity of 99% can be obtained in a
wave band of 700-1200nm. The
photonic crystal back reflector is suitable for serving as a back reflector of a unijunction
amorphous silicon thin film solar cell, a back reflector of a double-junction
amorphous silicon /
microcrystalline silicon laminated
solar cell and a back reflector of a triple-junction
amorphous silicon /
amorphous silicon germanium / amorphous
silicon laminated
solar cell. The photonic
crystal back reflector provided with the adjustable forbidden band and applied to the silicon-based thin-film solar
cell has the advantages that due to the fact that a photonic
crystal is used as the back reflector of the silicon-based thin-film solar
cell, the problems that an Ag back reflector is high in cost and other
metal back reflectors are low in reflectivity are solved, high efficiency and decrease of the cost of raw materials are guaranteed, improvement of the open-circuit
voltage of the
cell is facilitated, the stability of the cell is improved, the photonic
crystal back reflector is compatible with the
cell technology, reduction of equipment investment and the
plant area is facilitated, and productivity is improved.