Information Optical Technologies Centre, ITMO University, Saint Petersburg 197101, Russia.
Phys Chem Chem Phys. 2018 Oct 3;20(38):25023-25030. doi: 10.1039/c8cp04724c.
Quantum confinement and collective excitations in perovskite quantum-dot (QD) supercrystals offer multiple benefits to the light emitting and solar energy harvesting devices of modern photovoltaics. Recent advances in the fabrication technology of low dimensional perovskites has made the production of such supercrystals a reality and created a high demand for the modelling of excitonic phenomena inside them. Here we present a rigorous theory of Frenkel excitons in lead halide perovskite QD supercrystals with a square Bravais lattice. The theory shows that such supercrystals support three bright exciton modes whose dispersion and polarization properties are controlled by the symmetry of the perovskite lattice and the orientations of QDs. The effective masses of excitons are found to scale with the ratio of the superlattice period and the number of QDs along the supercrystal edge, allowing one to fine-tune the electro-optical response of the supercrystals as desired for applications. We also calculate the conductivity of perovskite QD supercrystals and analyze how it is affected by the optical generation of the three types of excitons. This paper provides a solid theoretical basis for the modelling of two- and three-dimensional supercrystals made of perovskite QDs and the engineering of photovoltaic devices with superior optoelectronic properties.
钙钛矿量子点（QD）超晶体中的量子限制和集体激发为现代光伏的发光和太阳能收集器件带来了多种好处。近年来，低维钙钛矿的制造技术取得了进展，使得这种超晶体的生产成为现实，并对其内部激子现象的建模提出了更高的要求。在这里，我们提出了一个具有正方形布拉维晶格的卤化铅钙钛矿 QD 超晶体中弗伦克尔激子的严格理论。该理论表明，这种超晶体支持三种明亮的激子模式，其色散和极化性质由钙钛矿晶格的对称性和 QD 的取向控制。发现激子的有效质量与超晶格周期与超晶体边缘处 QD 的数量的比值成正比，允许根据应用的需要对超晶体的光电响应进行微调。我们还计算了钙钛矿 QD 超晶体的电导率，并分析了它如何受到三种激子的光学产生的影响。本文为基于钙钛矿 QD 的二维和三维超晶体建模以及具有优异光电性能的光伏器件的工程设计提供了坚实的理论基础。
