Excitonic phenomena in perovskite quantum-dot supercrystals

Abstract

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.

Wide-Angle X-ray Diffraction Evidence of Structural Coherence in CsPbBr3 Nanocrystal Superlattices

“…Having a precise estimate of Λ that is independent of electron microscopy measurements is of key relevance for the study of LHP NC arrays, as NC orientation and spacing may strongly affect inter-NC effects, for example, exciton coupling. 21 , 22 …”

“…The utility of this parameter is demonstrated for two case studies: the contraction of NC SLs, hence the contraction of Λ, when the sample is put under vacuum (Figure ), and the actual formation of the SLs upon slow solvent evaporation (Figure ). Having a precise estimate of Λ that is independent of electron microscopy measurements is of key relevance for the study of LHP NC arrays, as NC orientation and spacing may strongly affect inter-NC effects, for example, exciton coupling. , …”

Band Structure and Intersubband Transitions of Three-Layer Semiconductor Nanoplatelets

“…The confinement of charge carriers in semiconductor nanostructures endows them with physical properties that are not observed in the macroworld [1][2][3][4][5][6] and which can be controlled at the fabrication stage or by exposing fabricated nanostructures to external stimuli, such as electric [7][8][9][10][11][12] or magnetic [13][14][15][16] fields. The properties of semiconductor nanostructures can be altered in many ways, because they depend on the material parameters, size, and shape of the nanostructure.…”

Nonlinear Optical Dynamics and High Reflectance of a Monolayer of Three-Level Quantum Emitters with a Doublet in the Excited State

“…The SC optical properties depend on the size of QDs, their shape, chemical composition, and lattice geometry and can be purposefully controlled (see [8] and the literature cited therein). So far, the energy structure [9][10][11] and linear optical properties [12,13] of 2D SCs of semiconducting QDs have been investigated. In these publications, large-scale capabilities of controlling the linear response of a 2D SC have been demonstrated, that provides a basis for application of such objects in nanophotonics.…”