Pradhan Bapi, Mushtaq Aamir, Roy Dipanwita, Sain Sumanta, Das Bidisa, Ghorai Uttam Kumar, Pal Suman Kalyan, Acharya Somobrata
School of Basic Sciences and Advanced Material Research Center , Indian Institute of Technology Mandi , Kamand , Himachal Pradesh 175005 , India.
Department of Industrial & Applied Chemistry, Swami Vivekananda Research Center , Ramakrishna Mission Vidyamandira , Belur Math, Howrah , West Bengal 711202 , India.
J Phys Chem Lett. 2019 Apr 18;10(8):1805-1812. doi: 10.1021/acs.jpclett.9b00832. Epub 2019 Apr 2.
All inorganic mixed-halide perovskite, CsPb(Br I) (0 ≤ x ≤ 1), nanocrystals possess tunable photoluminescence with high quantum yield in the visible window. However, the photoluminescence degrades rapidly with postsynthetic aging due to the spontaneous ion separation and phase instability. Here we show that the postsynthetic aging of CsPb(Br I) nanocubes spontaneously forms highly uniform single-crystalline nanowires with a diameter of 9 ± 0.5 nm and length of up to several micrometers. The nanowires show bright photoluminescence with an absolute photoluminescence quantum yield of 41%. Rietveld refinement identifies the stable orthorhombic phase of the nanowires, implying a phase transition from the cubic crystallographic phase of the nanocubes during the morphology evolution. Transient absorption spectroscopy reveals a faster excited-state decay dynamic with a large exciton delocalization length in 1D nanowires. Our findings elucidate the insights into the postsynthesis morphology evolution of mixed-halide perovskite nanocrystals leading to luminescent nanowires with excellent crystal phase stability for potential optoelectronic applications.
所有无机混合卤化物钙钛矿CsPb(BrₓI₁₋ₓ)（0 ≤ x ≤ 1）纳米晶体在可见光窗口具有可调谐的光致发光且量子产率高。然而，由于自发离子分离和相不稳定，合成后老化会使光致发光迅速降解。在此我们表明，CsPb(BrₓI₁₋ₓ)纳米立方体的合成后老化会自发形成高度均匀的单晶纳米线，其直径为9 ± 0.5纳米，长度可达几微米。这些纳米线显示出明亮的光致发光，绝对光致发光量子产率为41%。Rietveld精修确定了纳米线的稳定正交相，这意味着在形态演变过程中从纳米立方体的立方晶体相发生了相变。瞬态吸收光谱揭示了在一维纳米线中具有大激子离域长度的更快的激发态衰减动力学。我们的研究结果阐明了对混合卤化物钙钛矿纳米晶体合成后形态演变的见解，从而产生了具有优异晶相稳定性的发光纳米线，可用于潜在的光电子应用。
