飞秒激光刻蚀增强非晶硅薄膜太阳电池性能的研究

通过恒速移动线偏振飞秒激光焦点对非晶硅(a-Si) pin型薄膜太阳电池n型硅膜表面进行绒化刻蚀处理,形成不同周期间隔“凹槽”状结构.采用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对刻蚀后薄膜表面形貌进行了表征,证实了刻蚀区域表面能够诱导晶态多孔微结构形成.比较了飞秒激光刻蚀前后a-Si太阳电池的光电转换效率(η)、开路电压、短路电流密度和填充因子.结果表明,当飞秒激光脉冲能量为0.75 J/cm2、刻蚀周期间隔为15μm时,太阳电池光电转换效率达到14.9％,是未经过激光刻蚀处理电池光电转换效率的1.87倍.同时,反射吸收谱表明,电池表面多孔“光俘获”微结构的形成对其光电转换效率的提高起到了关键作用.

Study on the Performance Enhancement of Amorphous Silicon Thin Film Solar Cells by Femtosecond Laser Etching

An efficient light-trapping "porous-nanostructures" at different intervals on the n-type silicon surface of amorphous silicon (a-Si) pin type thin-film solar cells were fabricated using linearly polarized femtosecond lasers ablation by moving focal point at a certain speed.The surface morphology of the etching films was characterized by the scanning electron microscope (SEM) and X-ray diffractometer (XRD),and it was confirmed that the surface of the etching region could induce the formation of crystalline porous microstructures.Moreover,the photoelectric conversion efficiencies (η),open circuit voltages,short circuit current densities and fill factors of a-Si solar cells before and after femtosecond laser etching were compared.The results show that a-Si solar cells show a highest η of 14.9 ％ at the etching periodic interval of 15 μm and the femtosecond laser pulse energy of 0.75 J/cm2.The photoelectric conversion efficiency of the etched cell is 1.87 times as high as that of the cell without laser ablation.Meanwhile,the reflection absorption spectrum shows that the formation of the cell surface light-trapping porous nanostructures play a key role in improving the photoelectric conversion efficiency.