Strong Collectivity of Optical Transitions in Lead Halide Perovskite Quantum Dots
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Strong Collectivity of Optical Transitions in Lead Halide Perovskite Quantum Dots Junais Habeeb Mokkath1 Received: 1 September 2019 / Accepted: 1 November 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Perovskite quantum dots (QDs) are attractive semiconducting materials for large-scale and low-cost optoelectronic devices owing to their size-tunable bandgap, high photoluminescence quantum yield, and outstanding charge transport. Comprehending/understanding their fundamental photo-physical properties is of significant applied importance. However, first-principles theoretical studies elucidating their optical features are relatively less explored. In this study, we investigate the optical characteristics of CH3NH3PbX3 (X = I, Br, Cl) perovskite QDs having sizes below the Bohr exciton radius. We base our calculations on the linear combination of atomic orbitals (LCAO) real-time-propagation rt-TDDFT technique. Our results underline the strong collectivity in the optical excitations, ascertained using the decomposition weight of the electronhole transition via transition contribution maps. We also demonstrate an appealing route to tune the optical excitations subject to an external electric field. The results presented in this work will contribute to enhancing our understanding of the optical properties of perovskite QDs. Keywords TDDFT · Quantum dots · Strong collectivity
Introduction Hybrid organic-inorganic halide perovskites, with the representative system methylammonium lead iodide (CH3NH3PbI3 ), have shown surging research interest over the last few years as low-cost solution-processed materials with promising applications in photovoltaics [1–8], photocatalysis [9–11], light-emitting diodes [12–19], and thermoelectrics [20], to list a few. They feature the chemical formula of ABX3 , where A and B are monovalent and divalent cations, respectively, and X is a monovalent halide anion. The B cation (typically Pb or Sn), occupy
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11468-019-01062-0) contains supplementary material, which is available to authorized users. Junais Habeeb Mokkath
[email protected] 1
Department of Physics, Quantum Nanophotonics Simulations Lab, Kuwait College of Science And Technology, Doha Area, 7th Ring Road, P.O. Box 27235, Doha, Kuwait
the central site of an octahedron formed by six halide ions and a cation A, typically methylammonium (MA) or formamidinium (FA), located between the octahedra. Elements of the success of these materials can be associated with their flexibility in composition (different combinations of cations and anions) and morphology [21–24]. For instance, thin films of CH3NH3PbX3 (X = Cl, Br, I) yield tunable emission spectra: Cl (410 nm) −→ Br (530 nm) −→ I (780 nm). The majority of the research on halide perovskites are focused on their bulk materials. However, recently, their low-dimensional forms such as quantum dots (QDs) has been synthesized [25–36]. QDs allow facile and scala
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