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Universal Size-Dependent Stokes Shifts in Lead Halide Perovskite Nanocrystals.
The Journal of Physical Chemistry Letters ( IF 5.7 ) Pub Date : 2020-06-01 , DOI: 10.1021/acs.jpclett.0c01407
Michael C Brennan 1, 2 , Aaron Forde 3 , Maksym Zhukovskyi 4 , Andrew J Baublis 1 , Yurii V Morozov 1 , Shubin Zhang 5 , Zhuoming Zhang 1 , Dmitri S Kilin 6 , Masaru Kuno 1, 5
Affiliation  

Size-dependent photoluminescence Stokes shifts (ΔEs) universally exist in CsPbX3 (X = Cl, Br, or I) perovskite nanocrystals (NCs). ΔEs values, which range from ∼15 to 100 meV for NCs with average edge lengths (l) from approximately 13 to 3 nm, are halide-dependent such that ΔEs(CsPbI3) > ΔEs(CsPbBr3) ≳ ΔEs(CsPbCl3). Observed size-dependent Stokes shifts are not artifacts of ensemble size distributions as demonstrated through measurements of single CsPbBr3 NC Stokes shifts (⟨ΔEs⟩ = 42 ± 5 meV), which are in near quantitative agreement with associated ensemble (l = 6.8 ± 0.8 nm) ΔEs values (ΔEs ≈ 50 meV). Transient differential absorption measurements additionally illustrate no significant spectral dynamics on the picosecond time scale that would contribute to ΔEs. This excludes polaron formation as being responsible for ΔEs. Altogether, the results point to an origin for ΔEs, intrinsic to the size-dependent electronic properties of individual perovskite NCs.

中文翻译:

卤化钙钛矿纳米晶体中普遍的尺寸依赖性斯托克斯位移。

CsPbX 3(X = Cl ,Br 或I )钙钛矿纳米晶体(NCs)中普遍存在尺寸依赖的光致斯托克斯位移(ΔE s)。Δ ë小号值,其范围从〜15至100mev用于与平均边长(NCS)从约13至3nm,是卤化物依赖性使得Δ Ë小号(CsPbI 3)>Δ È小号(CsPbBr 3) ≳Δ ë小号(CsPbCl 3)。观察到的与尺寸相关的斯托克斯位移是不合奏尺寸分布的伪影通过单CsPbBr的测量证明3角NC斯托克斯位移(⟨Δ Ë小号⟩= 42±5兆电子伏),这是在相关联的合奏(接近定量协议= 6.8 ±0.8 nm)的Δ è小号值(Δ Ë小号≈50兆电子伏)。瞬态差分吸收测量还表明,在皮秒级的时间范围内没有显着的光谱动力学会影响ΔE s。这排除了极化子的形成对ΔE s的影响。总之,结果指向ΔE s的原点,是单个钙钛矿NC随尺寸变化的电子特性所固有的。
更新日期:2020-07-02
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