过渡金属Mn离子掺杂的半导体纳米晶研究进展

Controlled Synthesis and Optical Properties of Mn-doped Semiconductor Nanocrystals

过渡金属掺杂的纳米材料具有高效、稳定和可调谐的可见-近红外发射光谱的特点,尤其是由于大的斯托克斯位移而抑制了发光材料自吸收的问题,已经成为光学材料中一个重要的分支。回顾了关于Mn离子掺杂纳米晶研究进展中的几个关键问题。得到晶核掺杂和生长掺杂方式相比于传统的"一锅法"在制备方式更有优势;从回顾关于Mn掺杂机理上的各种解释和在宿主纳米晶中引入大量的掺杂剂所面临的困难中,得出要获得掺杂浓度可控的量子点需要考虑纳米晶表面自清洁效应,纳米晶形状、晶体结构、晶面、表面活性剂以及Mn离子与宿主阳离子的尺寸差别引入的晶格压力等关键因素;利用理论和实验深刻解释了Mn离子的发光机理,指出宿主到Mn离子的高能量转移速率是获得高效的Mn离子发光的关键因素。通过对掺杂量子点的制备、掺杂机理以及发光机理的综合探讨,为制备掺杂浓度和掺杂位置可控的光学性能优良的掺杂量子点方面的研究提供参考。

Doped nanocrystals （NCs） have become an important class of optical materials that exhibit efficient, stable and tuna- ble dopant emissions in visible and near infra-red （NIR） spectral windows, and the large ensemble Stokes shift for avoiding the self-absorption process. In this paper, we focus on some key issues in several selected topics on the most widely investigated Mn doped semiconductor NCs. It is started with an overview of important advances in synthesis methods of high quality Mn- doped NCs and emphasize on the recently proposed methods of nucleation-doping strategy and growth-doping strategy. Then by dealing with the fundamental principles and mechanism studies for the doping process, this paper has discussed the difficulties for insertion of more dopants in the semiconductor host. This paper pointed out that in order to prepare Mn-doped NCs with controllable dopants concentration, it should consider following factors such as the NCs surface self purification function; the shape, crystal structures, crystal plane and surface ligand of the NCs~ as well as the lattice pressure induced by the size differ- ence of Mn ions and the host cation. At last the theoretical explanation and experimental demonstration are provided to in depth understanding of their optical properties, and point out that the fast energy transferred from the host to the Mn d states is the key factor for obtaining Mmdoped NCs with high emission quantum yields. This paper have presented here the important ad- vances in synthetic techniques, Mn ions doping mechanism, and photophysical properties of Mn-doped semiconductor nano- crystals, and thus can help to synthesis high quality Mn-doped NCs with controllable concentration and location.