表面等离子激元吸收增强型太阳能电池机理的超快光谱研究

Photovoltaic conversion, as the most efficient method to solve the current energy crisis, has become one of the most popular research fields at present. However, the relative low conversion efficiency is the major development bottleneck for solar cell technology. Recently, many experiment studies indicate, the plasmonic absorption of surface metal nanoparticles is able to effectively improve the efficiency of solar cells; however, its physical mechanism is still unclear. Take such issue as the breakthrough point, this project proposes to measure the excited states dynamics of surface plasmonic enhanced solar cell with the aid of ultrafast spectroscopy, to analyze the energy transfer processes in samples by studying on the relationship between evolution (build-up and decay) processes of excited state and parameter (shape and size) of metal nanoparticles, and its impact of the samples on the photoelectric conversion efficiency, and to explore the physical mechanism of surface plasmonic enhanced absorption in solar cell. Therefore, to expand thoughts on the design of high efficient solar cells at low cost.

光伏转换作为解决能源问题最有效的方法，成为了当下热门的研究领域之一。而相对较低的转换效率是太阳能电池技术发展的主要瓶颈。近期，有许多实验工作表明，表面金属钠米颗粒的等离子吸收可以有效地提高太阳能电池的效率，但是其物理机制尚未清晰。本项目以此问题为出发点，提出借助超快光谱技术，对表面等离子吸收增强型太阳能电池的激发态动力学进行测量，通过寻找激发态的形成和衰变过程与金属纳米颗粒的形状和尺寸等参数之间的关系，以及对光电转换效率的影响，来分析该类样品中的能量传递过程，从而探索表面等离子激元引起太阳能电池吸收增强的的物理机制，为设计新型高效和低成本太阳能电池开阔思路。

围绕着本项目提出的：运用超快光谱技术研究太阳能电池材料的载流子动力学，以及表面等离子激元对该类材料弛豫过程的影响，来寻找设计新型高效太阳能电池的方法。我们开展了和完成了以下的工作：首先搭建了用来测量超快光谱的瞬态吸收和时间分辨荧光系统。在此基础上，研究了太阳能电池材料CZTS(Se)薄膜的载流子复合寿命，发现较快的复合速率是该类材料光电转换效率不高的主要原因之一；测量了太阳能电池材料InGaN薄膜，InGaN/GaN多量子阱的载流子弛豫特性，以及内部电场下的复合过程。发现内部电场能够显著的减缓载流子复合速率；对比了基于联噻唑的聚合物太阳能电池材料在不同极性环境中荧光态的复合过程，发现环境的极性对复合过程具有明显的影响；制备了Bi纳米颗粒，并对其非线性光学性质进行了测试，发现即使在非共振激发下，表面等离子效应也使得Bi纳米颗粒具有优异的非线性光学性质；制备了用于太阳能电池敏化剂的量子点材料CdSe/ZnS，以及CdSe/ZnS和Ag纳米颗粒的复合物，通过瞬态荧光技术研究了表面等离子激元对材料复合过程的影响。发现激子能量越接近表面等离子共振能量，复合速率越高。