Leem Jung Woo, Yu Jae Su
Department of Electronics and Radio Engineering, Kyung Hee University, Giheung-gu, Yongin-si, Gyeonggi-do, South Korea.
Opt Express. 2012 May 7;20(10):A431-40. doi: 10.1364/oe.20.00a431.
We fabricated the parabola-shaped subwavelength grating (SWG) nanostructures on indium tin oxide (ITO) films/Si and glass substrates using laser interference lithography, dry etching, and subsequent re-sputtering processes. The efficiency enhancement of an a-Si:H/μc-Si:H tandem thin film solar cell was demonstrated theoretically by applying the experimentally measured data of the fabricated samples to the simulation parameters. Their wetting behaviors and effective electrical properties as well as optical reflectance properties of ITO SWGs, together with theoretical prediction using a rigorous coupled-wave analysis method, were investigated. For the parabola-shaped ITO SWG/ITO film, the solar weighted reflectance (SWR) value was 10.2% which was much lower than that (i.e., SWR20%) of the conventional ITO film, maintaining the SWR values less than 19% up to a high incident angle of 70° over a wide wavelength range of 300-1100 nm. Also, the ITO SWG with a superhydrophilic surface property (i.e., water contact angle of 6.2°) exhibited an effective resistivity of 2.07 × 10(-3) Ω-cm. For the a-Si:H/μc-Si:H tandem thin film solar cell structure incorporated with the parabola-shaped ITO SWG/ITO film as an antireflective electrode layer, the conversion efficiency (η) of 13.7% was theoretically obtained under AM1.5g illumination, indicating an increased efficiency by 1.4% compared to the device with the conventional ITO film (i.e., η = 12.3%).
我们使用激光干涉光刻、干法蚀刻以及后续的再溅射工艺，在氧化铟锡（ITO）薄膜/硅和玻璃基板上制备了抛物线形亚波长光栅（SWG）纳米结构。通过将制备样品的实验测量数据应用于模拟参数，从理论上证明了非晶硅氢化（a-Si:H）/微晶硅氢化（μc-Si:H）串联薄膜太阳能电池的效率提高。研究了ITO SWG的润湿性、有效电学性能以及光学反射特性，并使用严格耦合波分析方法进行了理论预测。对于抛物线形ITO SWG/ITO薄膜，太阳加权反射率（SWR）值约为10.2%，远低于传统ITO薄膜的SWR值（即SWR~20%），在300 - 1100 nm的宽波长范围内，直至70°的高入射角，其SWR值均保持低于19%。此外，具有超亲水表面特性（即水接触角为6.2°）的ITO SWG的有效电阻率为2.07×10⁻³Ω·cm。对于将抛物线形ITO SWG/ITO薄膜作为减反射电极层的a-Si:H/μc-Si:H串联薄膜太阳能电池结构，在AM1.5g光照下理论上获得了13.7%的转换效率（η），这表明与使用传统ITO薄膜的器件（即η = 12.3%）相比，效率提高了1.4%。
