Ni2+掺杂和卤素空位填充协同抑制CsPbBr3纳米晶体中的离子迁移

卤化铅钙钛矿(LHPs)由于具有优异的光电性能和制备成本低等优点,已成为新一代光电器件的有力候选材料。然而,缺陷造成的离子迁移会导致LHPs纳米晶的晶体结构解离分解。因此,稳定性成为LHPs实际应用中亟待解决的问题。本文旨在研究镍离子替位掺杂及卤素空位填补对CsPbBr3纳米晶中的离子迁移抑制作用。通过离子迁移活化能的测定和高分辨透射电镜的原位观察,分析了前驱体掺杂剂对加强LHPs稳定性的作用原理。首先,选用乙酰丙酮镍和溴化镍作为掺杂剂,合成了掺杂LHPs纳米晶。其次,通过吸收-荧光光谱,X射线衍射,X射线光电子衍射,透射电子显微镜等测试手段对掺杂样品的光学及化学组成进行分析。最后,通过纳米晶薄膜电导率的温度依赖关系计算出其离子迁移活化能,并结合高分辨电镜原位观察纳米晶在高能电子束辐照下的形貌演变过程,揭示了不同掺杂剂对合成掺杂LHPs稳定性的影响。实验结果表明:Ni²⁺掺杂CsPbBr3样品的离子迁移活化能相较本征CsPbBr3样品(0.07 eV)有显著提升,其中乙酰丙酮镍掺杂样品的离子迁移活化能为0.238 eV,溴化镍掺杂样品的离子迁移活化能为0.487 eV。另外,电子束辐照测试表明溴化镍掺杂钙钛矿晶体表现出更高的结构稳定性,这主要归因于掺杂的Ni²⁺对卤素的强结合和卤素填补空位缺陷的协同钝化作用。Ni²⁺掺杂和卤素空位填充协同可以有效抑制卤化物钙钛矿纳米晶体中的离子迁移。

Suppressed ion migration in halide perovskite nanocrystals by simultaneous Ni2+ doping and halogen vacancy filling

Lead Halide Perovskites(LHPs)are promising candidates for next-generation optoelectronic application.However,defect-induced ion migration causes phase degradation in LHP nanocrystals.Therefore,material stability has become an urgent problem that impedes practical applications.In this paper,we aim to study the influence of doping cations on inhibiting the migration of halogen ions in perovskite nanocrystals.Through the measurement of ion migration activation energy and in-situ high-resolution transmission electron microscope technology,the effect of precursor dopants on the stability of LHPs were analyzed.Firstly,we synthesized two types of LHP nanocrystals with high crystal quality using nickel acetylacetonate and nickel bromide as precursor dopants,respectively.Secondly,the optical properties and component elements of the doped samples were analyzed by absorption-fluorescence spectroscopy,X-ray diffraction,X-ray photoelectron diffraction,and transmission electron microscopy.Finally,the ion migration activation energies of various LHP films were measured using temperature-dependent ion conductivity tests,and the influence of the precursor dopants on the stability of as-synthesized doped LHPs was compared with the results from high-resolution electron microscopy.The results showed that the activation energies of the doped CsPbBr3 samples were significantly improved compared to the intrinsic CsPbBr3 sample(0.07 eV),which were determined to be 0.238 eV for nickel acetylacetonate and 0.487 eV for nickel bromide.In addition,the electron irradiation experiments showed that the nickel bromide-doped perovskite nanocrystals exhibited higher structural stability.This is due to the strong bonding of doped Ni²⁺ to halogen and the synergistic passivation effect of halogen filling vacancy defects.It can be concluded that Ni²⁺ doping and halogen vacancy filling can effectively inhibit ion migration in halide perovskite nanocrystals.