金属离子掺杂提高全无机钙钛矿纳米晶发光性质的研究进展

Advances in improved photoluminescence properties of all inorganic perovskite nanocrystals via metal-ion doping

金属卤化物钙钛矿纳米晶由于其卓越的光电子性能,在发光二极管、激光器、X射线成像、太阳能电池及光电探测等领域中受到了极大的关注.与有机-无机杂化钙钛矿纳米晶相比,全无机钙钛矿CsPbX3(X=Cl,Br,I)纳米晶具有更优异的光电性能和更高的稳定性.为进一步提高CsPbX3纳米晶的光致发光量子效率和稳定性,有研究已经着手调控纳米晶的微观结构,减少作为非辐射复合中心的缺陷.近年来,在金属离子掺杂CsPbX3纳米晶过程中,发现不同种类和不同掺杂浓度的金属离子对其电子能带结构和光致发光性能有着巨大的影响,基于金属离子掺杂取得了光致发光量子效率接近100%的CsPbX3纳米晶.本文综述了近年来在CsPbCl3,CsPbBr3,CsPbI3和Mn^2+掺杂CsPbX3(Mn^2+:CsPbX3)四种体系中通过金属离子掺杂提高全无机钙钛矿纳米晶光学性能的研究进展及其性能提升的物理机制.此外,提出了下一步还需要深入研究的一些问题和策略,通过这些问题的深入研究,希望能促使全无机钙钛矿纳米晶在各种光电器件中得到更广泛的应用.

Metal halide perovskite nanocrystals(NCs)have attracted great attention in the fields of light-emitting diodes,lasers,X-ray imaging,solar cells and photoelectric detectors due to their excellent optoelectronic properties.Compared with organic-inorganic hybrid perovskite NCs,all inorganic perovskite CsPbX3(X=Cl,Br,I)NCs have good photoelectric properties and high stability.To further improve the photoluminescence(PL)quantum yields(QYs)and stability of CsPbX3 NCs,researchers reduced the defects as nonradiative recombination centers in NCs by the following strategies:1)surface treatment with different ligands;2)control of synthesis conditions with halide rich compounds;3)doping of metal ions.Among them,metal doping is considered as a universal and effective way to adjust the optoelectronic properties of semiconductors.It is found that the type and the concentration of metal ions have great influence on the electronic band structure and PL performance of NCs after the metal ions have been doped into CsPbX3 NCs.At the same time,compared with II-VI and III-V semiconductors,the unique structure of all inorganic perovskite NCs makes the doping of metal ions easier.Appropriate doping can not only enhance the intrinsic optical properties of the NCs without affecting their crystal structure,but also introduce new electronic energy levels into the NCs and new luminescent properties of doped metal ions.Based on metal ions doping strategy,the PLQYs of doped CsPbX3 NCs have been enhanced to nearly 100%.In this work,we summarize recent advances in metal doping of the four typical kinds of perovskite NCs,including CsPbCl3,CsPbBr3,CsPbI3,and Mn2+doped CsPbX3,and discuss the physical mechanisms of the improved properties through doping metal ions.It should be pointed out that the doping of some metal ions such as Ni2+and Cd2+into the above four kinds of NC systems can effectively passivate NC defects,thus improving the PL QY and stability of NCs.In addition,we put forward some personal perspectives on the future research subjects of interest and directions of metal doping for enhanced PL of CsPbX3 NCs,which needs to be further explored in order to promote extensive application of perovskite NCs to various optoelectronic devices.