CsPbX_(3)钙钛矿纳米晶中Mn(Ⅱ)离子的可控掺杂及其发光性能研究

Controlled Doping of Mn(Ⅱ)Ions in CsPbX_(3) Perovskite Nanocrystals and Luminescence Properties

Mn离子掺杂策略被广泛用于提高CsPbX3钙钛矿纳米晶(Nanocrystals,NCs)的稳定性和调控Pb的含量,但离子掺杂反应速率极快,不易控制。本文分别采用一步和两步热注射法对Mn^(2+)的掺杂含量进行大范围和精确调控,制备出具有不同Mn^(2+)掺杂含量的CsPbCl_(3)∶Mn^(2+)NCs。通过对其结构及发光性能的研究,将其区分为合金结构和掺杂结构,并进一步揭示了一步法和两步法进行Mn^(2+)调控时的不同机制,明确了在相同Pb∶Mn投料比的情况下,一步法合成的合金结构纳米晶具有更高的Mn^(2+)掺杂量,使得纳米晶在610nm左右与Mn相关的发射峰更为强烈,最高光致发光量子产为77%,而两步法合成的掺杂结构纳米晶在较少的Mn^(2+)情况下同样具有较高的光致发光量子产率。同时,Mn^(2+)的可控掺杂使得钙钛矿纳米晶的稳定性有效提升,放置四周后形貌和发光性能仍稳定。值得注意的是,合金结构对于本征激子发光稳定性的提升比掺杂结构更加有利。此外,还合成了具有优异发光性能的CsPb(Cl_(x)Br_(3-x))∶Mn^(2+)钙钛矿纳米晶,其荧光光谱可在404~640nm之间调控;但当Br-含量较高时,与Mn相关的发射峰消失,这是由于CsPbBr_(3)的能带与Mn^(2+)的^(4)T_(1-)^(6)A_(1)能级不匹配所致。本文强调了在CsPbCl_(3)∶Mn^(2+)钙钛矿制备过程中Mn^(2+)可控掺杂的重要性,对于实现纳米晶的可控合成具有重要意义。

Mn ion doping strategy emerged as a widely employed strategy for enhancing the stability of CsPbX3 perovskite nanocrystals(NCs)and regulating Pb content.Nevertheless,the rapid reaction rate associated with ion doping poses significant challenges for controllable synthesis.Herein,we have employed both the one-step and two-step hot injection methods to synthesize CsPbCl_(3)∶Mn^(2+)NCs with varying levels of Mn^(2+)doping,allowing for ap‐proximate and precise control of Mn^(2+)incorporation.Through an investigation of their structural and luminescent properties,these NCs are divided into alloy structure and doping structure,elucidating distinct mechanisms in‐volved in one-step and two-step Mn^(2+)regulation.The alloy structure nanocrystals synthesized by one-step method have higher Mn^(2+)doping amount than that by two-step method under the same Pb∶Mn feeding ratio.Consequently,the Mn-related emission peak of nanocrystals at about 610 nm is more intense with maximum photoluminescence quantum yield(PLQY)of 77%,and the PLQY of the doped nanocrystals synthesized by the two-step method is al‐so higher in the case of less Mn^(2+).At the same time,the controlled doping of Mn^(2+)improves the stability of perovskite nanocrystals,and the original morphology and luminescence properties remained stable after four weeks.Notably,alloy structure is more favorable for improving the luminescence stability of intrinsic excitons compared with doping structure.In addition,CsPb(Cl_(x)Br_(3-x))∶Mn^(2+)perovskite nanocrystals with excellent luminescent properties have been synthesized.The fluorescence spectrum can be regulated between 404-640 nm,but when the Br-content is high,the emission peak associated with Mn disappears.This is due to the mismatch between the energy band of CsPbBr_(3) and the ^(4)T_(1-)^(6)A_(1) energy level of Mn^(2+).This paper emphasizes the significance of precise Mn^(2+)doping control in the preparation of CsPbCl_(3)∶Mn^(2+)perovskite NCs,which is of great significance for the controlled synthesis of nanocrystals.