奈米幾何結構對矽晶薄膜太陽能電池光學吸收之影響與研究

Abstract

本論文是利用有限時域差分法對於2μm厚之薄膜矽晶提出三種不同之表面奈米結構(包含:奈米柱、奈米錐與奈米鏡陣列)並對其光學吸收提升進行數值計算。相較於奈米柱與奈米錐陣列，奈米鏡陣列展示出了最高能量轉換效率。此結果主因於奈米鏡陣列具有將入射光耦合至共振模態的能力，使得入射光子於長波長區間可增加其光學路徑。而本研究中，奈米柱、奈米錐與奈米鏡陣列其最佳能量轉換效率分別為η=17.4%、18.8%與22.0%。而奈米柱、奈米錐與奈米鏡陣列相對於具有抗反射模之平面矽晶薄膜來說，其轉換效率分別提升為26.1%、36.2%與59.4%。這些發現顯示出矽晶薄膜太陽能電池於其表面製作奈米結構將可提升光學之吸收。

We apply the finite difference time domain method to numerically calculate the enhanced optical absorption of three nanostructures (i.e., nanorod, nanocone, and nanolens arrays) that were decorated on the surface of 2 µm thick crystal silicon thin films. Compared with the nanorod and nanocone arrays, the nanolens array exhibits the highest power conversion efficiency. This result is mainly attributed to the natural capability of the nanolens array to optically couple incident light into in-plane guided modes, which increases the optical path of the incident photons in the long-wavelength regime. The power conversion efficiencies of the optimized nanorod, nanocone, and nanolens arrays are =17.4%, 18.8%, and 22.0%, respectively. These efficiencies correspond to enhancements of 26.1%, 36.2%, and 59.4% for the nanorod, nanocone, and nanolens arrays, respectively, compared with a planar Si thin-film with a standard quarter-wavelength antireflection layer. These findings show promises for the nanostructured design of silicon thin-film solar cells that exhibit enhanced optical absorption.