- 學位論文
利用Spin-on Film 技術製作漸變式折射率的多層抗反射層膜應用於Ⅲ-Ⅴ族太陽能電池之研究
Multi-layer Anti-Reflection Coatings of Graded Index on Ⅲ-Ⅴ Solar Cell Using Spin-on Film Technology
摘要
本研究探討寬波域(broad band)與低反射率的多層抗反射薄膜之應用，來獲得高效率Ⅲ-Ⅴ族太陽能電池。為了使太陽能電池能有效的吸收太陽能光譜及降低表面反射率，我們使用Spin-on film (SOF) 技術製作出漸變式折射率(graded index)的多層抗反射層膜。由於SOF技術具有低成本、製程簡易及可用於大面積製程等特點，是相當適合應用於抗反射層膜之製作。 Ⅲ-Ⅴ族太陽能電池的優點為：(1)因為是直接能隙半導體所以電子容易躍遷，(2)具抗輻射能力，(3) 有較高的光吸收係數，電池只需要幾微米的厚度就可以吸收大部分的太陽光。 本文先利用SOF技術製作在Si基板上形成抗反射膜及進行反射率頻譜的分析，波長在440到640nm的波段有極低的反射率，其平均反射率為2.3%。我們再利用SOF方法在GaAs太陽能電池上製作出多層抗反射層膜，並成功製作出高效率Ⅲ-Ⅴ族太陽能電池。在AM1.5G、25˚C條件下，其單接面的GaAs太陽能電池在未形成多層抗反射層膜前，開路電壓(open circuit voltages , Voc)為1.07 V、短路電流密度 (short circuit current density , Jsc)為21.47 mA/cm2、填充因子(fill factor , FF)為84.84%、轉換效率(conversion efficiency , η)為19.45 %；在GaAs電池上用SOF技術去形成SiO2/TiO2/TiO2 三層抗反射層膜後，開路電壓為1.07 V、短路電流密度增加為28.74 mA/cm2、填充因子為84.05%、轉換效率更提高為25.83%。另外在InP蕭特基太陽能電池，在無抗反射膜，其太陽能電池開路電壓為0.73 V、短路電流密度為20.71 mA/cm2、填充因子為61.73%、轉換效率為10.69%，在表面覆蓋抗反射膜後，其開路電壓為0.73 V、短路電流密度增加為24.99 mA/cm2、填充因子為61.77%，而轉換效率提升至12.92 % 。
並列摘要
In this study, we investigate the application of optimized broadband and low reflectance of multi-layer anti-reflection thin films to fabricate a high efficiency Ⅲ-Ⅴ solar cell. For that the solar cells absorbed effectively solar spectrum and reduced surface reflectance, we use spin-on film (SOF) technology to fabricate multi-layer anti-reflection coatings (ARCs) of graded index. Owing to its potential low cost, reduced complexity and adaptability to large scale batch processing, SOF process is desirable techniques for deposit ARCs. The advantages of Ⅲ-Ⅴ solar cells contain (1) electron is easy to transit because Ⅲ-Ⅴ material is direct semiconductor, (2) with the ability of anti-radiation, (3) has high absorption coefficient, and requires a cell only a few microns thick to absorb most sunlight. In this thesis, at first, the reflection spectrum analysis shows that the spin-on thin films on Si-wafer, and there is an extremely low average optical reflectance of 2.3% in wavelength of 440-640 nm. And then, we use SOF method to prepare multi-layer ARCs for GaAs solar cells and have successfully fabricated high efficiency Ⅲ-Ⅴ solar cells. At AM1.5G, 25˚C, for single-junction GaAs solar cell without multi-layer ARCs, the open circuit voltages (Voc) was 1.07 V, short circuit current density (Jsc) was 21.47 mA/cm2, fill factor (FF) was 84.84%, and the conversion efficiency (η) was 19.45 %; after using SOF method to form triple-layer SiO2/TiO2/TiO2 ARCs on GaAs solar cell, the open circuit voltages (Voc) was 1.07 V, short circuit current density (Jsc) increased to 28.74 mA/cm2, fill factor (FF) was 84.05%, and the conversion efficiency (η) even enhanced to 25.83%. In addition, for InP Schottky solar cell without ARC, the open circuit voltages (Voc) was 0.73 V, short circuit current density (Jsc) was 20.71 mA/cm2, fill factor (FF) was 61.73%, and the conversion efficiency (η) was 10.69%; after covering the surface with ARC, the open circuit voltages (Voc) was 0.73 V, short circuit current density (Jsc) increased to 24.99 mA/cm2, fill factor (FF) was 61.77%, and the conversion efficiency (η) enhanced to 12.92%.