利用陷光结构增加硅薄膜太阳能电池的吸收效率

Enhancement of Light Absorption in Thin Film Silicon Solar Cells with Light Traping

提出了一种含有光锥光子晶体防反射层和四棱锥光栅背反射层的a-Si薄膜太阳能电池结构,吸收层厚1μm,总厚度为1.45μm。根据光子晶体及亚波长光栅的衍射特性,利用严格耦合波方法对器件参数进行了优化。计算结果表明：当光锥结构倾角θ=72°、晶格常数T1=1 200 nm、介质底半径r=100 nm时,防反射层的透射率较高,在300-600 nm波长范围内,该薄膜太阳能电池的吸收效率比不含防反射层电池提高了11.54%;当四棱锥光栅结构周期L=1.2μm、占空比f=0.38、槽深h5=560 nm时,背反射层的反射效果较好,在600-850 nm波长范围内,电池的吸收效率提高了3.75%。所设计的薄膜电池结构在波长为300-750 nm、入射角为0°-75°范围内的吸收效率均在80%以上,平均吸收效率达92%,满足太阳电池对宽频谱、广角度的光俘获的要求。

An amorphous silicon thin-film solar cell with an anti-reflection coating of light cone photonic crystal and a back surface field layer of rectangular pyramid grating is proposed. The thickness of the cell is 1. 45 μm and the thickness of the absorbing layer is 1 μm. Using Rigorous Coupled Wave Analysis method,the parameters of the cell are optimized based the diffraction characteristics of the photonic crystal and the sub-wavelength grating. When the light cone angle is 72°,the lattice constant is 1 200 nm,and the bottom radius is 100 nm,a relative increase of 11. 54% for the integrated absorption inside the solar cell can be achieved between 300 nm and 600 nm,compared to an equivalent but no anti-reflection coating cell. When the rectangular pyramid grating period is 1. 2 μm,the duty cycle is 0. 38,and the depth of the grating is 560 nm,a relative increase of 3. 75% for the integrated absorption inside the solar cell can be achieved between 600 nm and 850 nm. According to the simulation,the absorption of the designed thin-film solar cell is over than 80% in the incident angle range of 0°- 75° and the wavelength between 300 nm and 750 nm,and the average absorption is up to 92%. This solar cell is designed to meet the demanding requirements of a wide spectrum and wide-angle light capture.