基于石墨烯/一维硅纳米阵列新型光伏器件的研究

Recently, photovoltaice devices based on one-dimensional (1D) Si nano-arrays have attracted considerable attention due to the strong light absorption arising from the light trapping effect as well as the radial p-n junction structure formed in the Si nano-arrays, which can greatly facilitate the separation of the photo-generated carriers. However, the complex device fabrication process inherited from the conventional crystal-Si photovoltaic devices, such as high-temperature p-n junction diffusion or growth, will inevitably restricted their practical applications. Herein, we propose to fabricate graphene/Si nano-array hybrid devices via a simple transfer process at room temperature and ambient environment. Two types of photovoltaic devices will be constructed, including graphene/Si nano-array Schottky junction devices and graphene/polymer/Si nano-array organic/inorganic hybrid p-n junction devices. We will focus on the structure optimization of Si arrays, pursue of full contact between graphene and Si arrays, surface modification and passivation of the arrays, as well as tuning the electrical properties of graphene, to improve the device performances. Furthermore, flexible photovoltaic devices will be constructed by peeling off the Si nano-arrays from the etching/growth substrates. It is expected that photovoltaic devices with efficiency in the range of 10-15% (9-12% for flexible devices) will be achieved in this project. This project has important sense in the development of high-efficiency, low-cost, and environment-friendly carbon/silicon hybrid photovoltaic device.

一维硅纳米阵列结构具有陷光效应，且易于构筑径向p-n结，有利于改善器件光吸收效率及载流子分离效率，其在光伏电池中的应用引起广泛关注。但现有一维硅纳米阵列光伏器件主要沿用传统晶硅器件制备工艺，如高温下p-n结扩散或生长，工艺的复杂性对其应用和性能造成限制。本项目提出以石墨烯作为高性能透明电极，在大气及室温条件下，通过简单转移方式与一维硅纳米阵列构成肖特基型或有机-无机杂化p-n结光伏器件。通过阵列结构优化、石墨烯与阵列立体接触等方式，改善石墨烯与阵列接触。进而结合阵列表面修饰与钝化，以及石墨烯电学性能调控等手段，提高光伏器件性能。通过发展硅纳米阵列剥离与转移技术，构筑柔性光伏器件。期望获得转换效率在10-15%之间（其中柔性器件9-12%）的高性能石墨烯/一维硅纳米阵列光伏器件，器件性能具国际先进水平。本项目的实施对于高效、低成本、环境友好的碳/硅复合光伏器件的研究与应用具有重要意义。

石墨烯/硅异质结太阳能电池具有结构简单，可溶液法加工等特点，有望成为一种新型的高性能、低成本太阳能电池。一维硅纳米阵列结构具有良好的陷光效应，我们通过构筑基于硅纳米结构的石墨烯／硅异质结太阳能电池，利用硅纳米结构进行光学调控，有效增强了器件的吸光，进而提升了器件的光电转换效率。我们同时采用硅表面旋涂聚合物薄膜减反层的方法提高硅的光吸收，也取得了较好的减反射效果，最终获得效率超过13.5%的高效率石墨烯/硅异质结器件。此外，我们通过界面调控优化异质结的载流子分离和传输的性质，采用硅表面甲基化、表面沉积P3HT或石墨烯量子点等方法调控硅表面能带弯曲，减少硅的表面载流子复合，从而提高器件效率。我们在柔性硅太阳能电池方面开展了系统的研究，为了克服柔性超薄硅光吸收弱的缺点，我们在其表面构筑了硅纳米线阵列，有效降低了表面光反射，最终得到效率超过8%的石墨烯／柔性硅电池器件。在石墨烯／硅异质结太阳能电池的研究基础上，我们进一步发展了基于MoS2等垂直取向二维材料薄膜/硅纳米结构异质结光电器件，构筑了具有宽光谱探测、高探测率和高响应速度的高性能光电探测器。我们的工作有力提升了石墨烯/硅异质结太阳能电池的性能，对于发展基于二维材料/硅异质结的新型光伏与光电器件具有重要意义。