基于金属纳米颗粒/透明介质层/砷化镓一维半导体复合纳米结构的光伏器件性能调控与机理研究

Due to their interesting optical and electrical properties compared to the flat structure, Gallium Arsenic (GaAs) nanowires (NWs) arrays have shown promising performance when used to fabricate next-generation solar cells. In the past few years, considerable work has been devoted to optimizing the NW’s preparation and device fabrication process. But less attention has been paid on adjusting the compositions and structures to improve the performance of the photovoltaic devices based on GaAs NWs. In this project, we propose a photovoltaic device, which is consisting of III-V nanowire decorated with the metal nanoparticles and transparent dielectric layer. Through interaction with surface plasmons of the metal nanoparticles, the incident light is resonantly coupled with the trapped waveguide modes of the semiconductor NW. This significantly increases the optical absorption of light in the active layer and improves photoelectron generation. Meanwhile, the surface passivation effects introduced by the addition of some transparent dielectric coatings can reduce the surface recombination rate. To improve the performance of such cells, the physical mechanism is firstly to be studied to understand the enhanced absorption in the decorated GaAs NW. Then, a systematic study on the influence of the compositions and structures of the proposed photovoltaic devices on the efficiency of the enhancement is to be performed. The successful implementation of this project will provide a new strategy to the fabrication of GaAs based nano-devices.

结合砷化镓材料独特的光电特性和一维纳米阵列在微尺度下展现出的新奇物理性质设计新型纳米光伏器件，是保证器件光电转换效率，降低制作成本的有效途径。目前，科研人员主要通过优化材料性能和器件工艺来提高电池输出特性，很少有研究探索纳米器件组成和结构改进对器件光电性能的影响。本项目通过在砷化镓纳米线表面修饰金属纳米颗粒和透明介质层，结合金属纳米颗粒的表面等离子激元效应和致密透明介质层的表面钝化作用提高器件的光电性能。我们将通过光反射谱和光学模拟，理解金属表面等离子激元增强半导体纳米线光吸收的物理机制，同时结合光电耦合分析和光伏器件输出性能表征，揭示阵列的组成、结构与器件光电特性之间的关联性。本项目的成功实施可为器件优化提供制备经验和科学依据，并为基于一维纳米结构光电器件的开发提供新设计思路。

在本项目中，我们主要研究纳米阵列电池组成、结构与器件光电特性之间的关联性，结合光电耦合分析揭示光伏器件输出性能的影响因素。首先，结合胶体球刻蚀技术和镓辅助分子束外延技术制备有序砷化镓纳米阵列，通过控制原始胶体球直径控制砷化镓纳米线的周期，控制催化剂液滴的尺寸进而实现砷化镓纳米线直径的控制，实现了两英寸衬底上砷化镓纳米阵列的制备。进一步，通过在半导体纳米线表面修饰透明介质层，结合致密透明介质层光学模式增强和表面钝化作用提高器件的光吸收性能。同时，通过光反射谱和光学模拟，理解光学模式增强半导体纳米线光吸收的物理机制。在此基础上，设计了新型GaInP纳米阵列/硅薄膜两结光伏器件，并提出了透过调节介质层厚度实现两结串联电池电流匹配的新思路。通过细致平衡原理计算，并结合表面复合数据，获得光伏器件在AM1.5G标准太阳光照射下开路电压Jsc=18.72mA/cm2，Voc=1.88V， FF=0.85， 电池效率可达η=29.9%。本项目工作可为器件优化提供制备经验和科学依据，并为基于一维纳米结构光电器件的开发提供新设计思路。