胶体量子点激子动力学及其纳米金属表面等离子体调控机制

As the energy needs of today's society is growing increasingly tense, to improve power conversion efficiency of solar cells appear particularly important and urgent. Effective acquisition of photo carrier and separation of multiple exciton in quantum dots are expected to break through the bottlenecks of lower conversion efficiency of solar cells, so the study on exciton dynamics have been a hotspot issue in our world today..This proposal put firstly forward to improve the conversion efficiency of solar cells by using localized field enhancement and spectral tuning properties of nanometal surface plasmon.Firstly, utilizing the effect of local field enhancement improve the exciton transport, mobility and collection of multiple carriers. Secondly, utilizing spectral tuning properties acquire efficiently radiant energy in the infrared region for about 44% of the entire solar energy observed on earth..The contents of research concern primarily with 1)the generation, recombination, relaxation, transport, and separation process of exciton under surface plasmon of nano-metallic periodic structure, 2)transport and collection process of charge carrier (electron and hole) due to exciton forming, 3) energy transfer in colloidal quantum dots from infrared radiation absorbed by nano-metallic periodic structure, 4) to explore improving methods of optical and electrical properties for colloidal quantum dots FET configuration with nano-metallic structure..This proposal aims itself at providing theoretical basis for preparation of high performance photoelectric material as well as technological foundation for solar-cells with highly-efficient power conversion,photodetectors with high detectivity and LED with low power consumption and high brightness.

在能源需求日趋紧张的当今社会，提高太阳能电池转换效率显得尤为重要和迫切。量子点中多激子分离和光生载流子有效提取有望突破太阳能电池转换效率低的瓶颈，因此激子动力学已经成为国际研究的热点。本项目首次提出用纳米金属等离子体的局域光场增强和光谱调谐功能提高太阳能电池的转换效率。首先，用局域光场增强效应提高激子转运和光生载流子输运提取能力；其次，用光谱调谐效应有效获取太阳能中大约44%的红外辐射。主要研究周期性纳米金属等离子体作用下，胶体量子点中激子的生成、复合、驰豫和离化过程；激子形成电荷载流子（电子和空穴）后的输运获取过程；纳米金属结构吸收的红外辐射在胶体量子点中的能量转移；探索具有纳米金属结构的胶体量子点场效应管的电学和光学特性改善方法。项目目标是为制备高性能的光电材料提供理论基础，也为高转换效率的太阳能电池、高灵敏度的光探测器以及低功耗高亮度的发光二极管等器件的制备提供技术基础。

本项目主要研究了金属纳米等离子体与量子点的相互作用，希望通过金属纳米等离子体的物理特性来增强量子点的发光强度。主要研究内容包括：1) 周期性纳米金属等离子体作用下，胶体量子点中激子的生成、复合、输运和离化过程；2）激子形成电荷载流子（电子和空穴）后的输运获取过程；3）纳米金属结构吸收的红外辐射能在胶体量子点中的能量转移；4）探索胶体具有金属纳米结构的胶体量子点场效应管的电学和光学特性改善方法。.结果表明：1）表面等离子体对量子点中激子的影响主要是近场效应，这种影响不仅有能量转移效应而且还存在载流子(空穴和电子)的电荷转移过程。如果量子点与纳米金属之间距离太近，激子中的空穴将会与金属中的电子复合，形成焠灭效应。量子点与纳米金属之间一般存在一个最佳距离，使得量子点的发光强度最大。2）纳米金属与量子点之间的能量传递与量子点导带的波函数和金属纳米等离子体的波函数的交叠有关，重叠越大耦合效率越高。3）当纳米金属内部的表面等离子体的共振能量略大于量子点导带电子跃迁能量时，能量从纳米金属传递到量子点；反之，则能量从量子点传递到纳米金属。这些结果为进一步提高量子点光电子功能器件提供了有力的证据。