Department of Chemistry, University of California Berkeley , Berkeley, California 94720, United States.
Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
J Am Chem Soc. 2017 May 17;139(19):6566-6569. doi: 10.1021/jacs.7b02817. Epub 2017 May 4.
We demonstrate postsynthetic modification of CsPbBr nanocrystals by a thiocyanate salt treatment. This treatment improves the quantum yield of both freshly synthesized (PLQY ≈ 90%) and aged nanocrystals (PLQY ≈ 70%) to within measurement error (2-3%) of unity, while simultaneously maintaining the shape, size, and colloidal stability. Additionally, the luminescence decay kinetics transform from multiexponential decays typical of nanocrystalline semiconductors with a distribution of trap sites, to a monoexponential decay, typical of single energy level emitters. Thiocyanate only needs to access a limited number of CsPbBr nanocrystal surface sites, likely representing under-coordinated lead atoms on the surface, in order to have this effect.
我们通过硫氰酸盐盐处理展示了 CsPbBr 纳米晶体的后合成修饰。这种处理将新合成的（PLQY≈90%）和老化的纳米晶体（PLQY≈70%）的量子产率提高到接近单位（2-3%的测量误差），同时保持形状、尺寸和胶体稳定性。此外，荧光衰减动力学从具有陷阱位点分布的纳米晶半导体的多指数衰减转变为单指数衰减，这是单能级发射器的典型特征。硫氰酸盐只需要与有限数量的 CsPbBr 纳米晶体表面位点接触，可能代表表面上配位不足的铅原子，才能产生这种效果。
