平顶激光退火制备纳米Ag基透明导电陷光结构薄膜及其太阳能电池的研究

In this project, we proposed to prepare Ag nanoparticles integrated within transparent conducting oxide (TCO) thin films on the glass substrates by use of frequency-doubled Nd:YAG laser (λ=532nm) with a flat-top beam, which was introduced by two-stage fly-eye lens array, as the front electrodes of Si-based thin film solar cells. In order to research the newly growth process of TCO thin films with low resistivity, high transmittance and high thermal stability in visible and near infrared regions of solar spectrum annealed by energy-controlled laser, nano-Ag based TCO films with light-trapping surface and Ag nanoparticles controlled with plasmonic resonance have been constructed. We research the structure, optical and electrical properties in nano-Ag based TCO films and optimize plasma enhanced chemical vapor deposition process of the µc-Si:H(p)/a-SiOx:H(p) film with wide band gap and high conductivity as window-layer for solar cell. Optimization design of nano-Ag based TCO films has been made to enhance light absorption and conversion efficiency of thin film solar cells. This research work is very essential to open a new prospect to explore the fabrication of TCO films by laser annealing at low temperature and provide valuable basis for design and improvement of TCO films for Si-based thin film solar cells with broader spectrum and high conversion efficiency. .

本项目主要采用两级蝇眼整形的Nd:YAG（波长为532nm）平顶激光退火在玻璃衬底上制备了以纳米Ag基透明导电薄膜作为硅薄膜太阳电池的前电极材料。以探索能量可控的激光热退火新生长工艺制备在可见光和红外光范围低阻高透热稳定性高的透明导电薄膜为目标，设计构建了具有纳米陷光结构的Ag基透明导电复合薄膜以及有序可调的Ag等离子体共振效应的纳米颗粒体系。通过研究纳米Ag基透明导电复合薄膜的结构、光电性能和设计以宽带隙、高电导µc-Si:H(p)/a-SiOx:H(p)为窗口层的能带渐变缓冲层结构的等离子体增强化学气相沉积工艺条件，分析了增强太阳电池光吸收和提高转换效率的硅薄膜太阳电池结构的优化设计。本研究工作为探索激光退火低温制备透明导电薄膜的工艺开拓了新思路，并为寻找适合于宽光谱高效硅基薄膜太阳电池的透明导电薄膜材料的设计和研究提供了依据，具有十分重要的研究价值。

通过陷光结构的设计提高太阳能电池的转换效率己成为太阳能电池研究的热点问题。金属表面等离子体纳米结构在局域能量增强和宽带吸收方面表现出优良的性能，因而在薄膜太阳能电池结构设计中展现出重要的价值。利用Ag纳米颗粒激发的表面等离子体共振（SPR）频率在可见光或红外区，以此通过对入射光进行散射和俘获来加强对太阳光的吸收和利用，这对于提高Si基薄膜太阳能电池的转换效率是一种非常重要的方法。本项目从减少光反射损失和拓宽光谱吸收范围出发，通过薄膜制备工艺和热退火处理，特别是利用先进的激光退火工艺来高效、快速制备具有纳米陷光结构的Ag基透明导电薄膜以及有序可调的具有Ag等离子体共振效应的纳米颗粒体系。通过调控制膜工艺和退火方式，制备出多种形貌Ag纳米颗粒，AZO/Ag/AZO薄膜表现出红外SPR特性。具有纳米陷光结构AZO/Ag/AZO薄膜经过退火后品质因子可达4.8 10-2Ω-1。研究以宽带隙、高电导µc-Si:H(p)/a-SiOx:H(p)为窗口层的界面缓冲层结构的等离子体增强化学气相沉积工艺条件，结合多种Ag背反射电极设计，研究Ag SPR效应在Si薄膜太阳电池TCO前电极结构中增强光吸收和提高电池转换效率的原理，提出最佳纳米Ag基透明导电薄膜的结构设计。上述研究成果在提高Si薄膜太阳电池相关构件材料的性能以及电池结构的优化设计，进而提高Si薄膜太阳电池转换效率等方面具有重要的参考价值。