Nanotechnology. 2016 Aug 12;27(32):325708. doi: 10.1088/0957-4484/27/32/325708. Epub 2016 Jun 29.
Green photoluminescence (PL) from CsPbBr3 nanocubes (∼11 nm edge-length) exhibits a high quantum yield (>80%), narrow spectral width (∼85 meV), and high reproducibility, along with a high molar extinction coefficient (3.5 × 10(6) M(-1) cm(-1)) for lowest energy excitonic absorption. In order to obtain these combinations of excellent properties for blue (PL peak maximum, λ max < 500 nm) emitting samples, CsPbBr3 nanocubes and nanoplatelets with various dimensions were prepared. Systematic increases in both the optical gap and transition probability for radiative excitonic recombination (PL lifetime 3-7 ns), have been achieved with the decreasing size of nanocubes. A high quantum yield (>80%) was also maintained, but the spectral width increased and became asymmetric for blue emitting CsPbBr3 nanocubes. Furthermore, PL was unstable and irreproducible for samples with λ max ∼ 460 nm, exhibiting multiple features in the PL. These problems arise because smaller (<7 nm) CsPbBr3 nanocubes have a tendency to form nanoplatelets and nanorods, eventually yielding inhomogeneity in the shape and size of blue-emitting nanocrystals. Reaction conditions were then modified achieving nanoplatelets, with strong quantum confinement along the thickness of the platelets, yielding blue emission. But inhomogeneity in the thickness of the nanoplatelets again broadens the PL compared to green-emitting CsPbBr3 nanocubes. Therefore, unlike high quality green emitting CsPbBr3 nanocubes, blue emitting CsPbBr3 nanocrystals of any shape need to be improved further.
CsPbBr3 纳米立方体（11nm 边长）具有高光致发光量子产率（>80%）、窄光谱带宽（85meV）和高重现性，同时具有高摩尔消光系数（3.5×10^6M^-1cm^-1），用于最低能量激子吸收。为了获得这些具有优异性能的蓝色（PL 峰最大值，λmax<500nm）发射样品，制备了具有不同尺寸的 CsPbBr3 纳米立方体和纳米薄片。随着纳米立方体尺寸的减小，光学带隙和辐射激子复合（PL 寿命 3-7ns）的跃迁概率都得到了系统的增加。高量子产率（>80%）也得到了保持，但对于蓝色发射的 CsPbBr3 纳米立方体，光谱宽度增加且变得不对称。此外，对于 λmax∼460nm 的样品，PL 不稳定且不可重现，在 PL 中表现出多个特征。这些问题是由于较小的（<7nm）CsPbBr3 纳米立方体倾向于形成纳米薄片和纳米棒，最终导致蓝色发射纳米晶体的形状和尺寸不均匀。然后，通过修改反应条件，实现了具有强烈厚度量子限制的纳米薄片，从而产生蓝色发射。但是，纳米薄片厚度的不均匀性再次使 PL 比绿色发射的 CsPbBr3 纳米立方体更宽。因此，与高质量的绿色发射 CsPbBr3 纳米立方体不同，任何形状的蓝色发射 CsPbBr3 纳米晶体都需要进一步改进。
