Department of Nanophotonics and Metamatarials, ITMO University, 49 Kronverkskii pr., Saint Petersburg 197101, Russia.
Nanoscale. 2019 Apr 4;11(14):6747-6754. doi: 10.1039/c8nr09837a.
Halide perovskite nanoparticles have demonstrated pronounced quantum confinement properties for nanometer-scale sizes and strong Mie resonances for 102 nm sizes. Here we studied the intermediate sizes where the nonlocal response of the exciton affects the spectral properties of Mie modes. The mechanism of this effect is associated with the fact that excitons in nanoparticles have an additional kinetic energy that is proportional to k2, where k is the wavenumber. Therefore, they possess higher energy than in the case of static excitons. The obtained experimental and theoretical results for MAPbBr3 nanoparticles of various sizes (2-200 nm) show that for particle radii comparable with the Bohr radius of the exciton (a few nanometers in perovskites), the blue-shift of the photoluminescence, scattering, and absorption cross-section peaks related to quantum confinement should be dominating due to the weakness of Mie resonances for such small sizes. On the other hand, for larger sizes (more than 50-100 nm), the influence of Mie modes increases, and the blue shift remains despite the fact that the effect of quantum confinement becomes much weaker.
卤化物钙钛矿纳米粒子在纳米级尺寸上表现出明显的量子限制特性，在 102nm 尺寸上表现出强烈的 Mie 共振。在这里，我们研究了中间尺寸，其中激子的非局域响应会影响 Mie 模式的光谱特性。这种效应的机制与这样一个事实有关，即纳米粒子中的激子具有与 k2 成正比的额外动能，其中 k 是波数。因此，它们具有比静态激子更高的能量。对于各种尺寸（2-200nm）的 MAPbBr3 纳米粒子，我们得到了实验和理论结果，表明对于与激子玻尔半径相当的粒子半径（在钙钛矿中为数纳米），与量子限制相关的光致发光、散射和吸收截面峰值的蓝移应该占主导地位，因为对于如此小的尺寸，Mie 共振较弱。另一方面，对于较大的尺寸（超过 50-100nm），Mie 模式的影响增加，尽管量子限制的影响变得较弱，但蓝移仍然存在。
