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

Abstract

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%.