Date of Award

2021

Publisher

North Dakota State University

Document Type

Dissertation

Degree Awarded

Doctor of Philosophy (PhD)

Program

Materials and Nanotechnology

College

Interdisciplinary Studies

Faculty Advisor

Kilin, Dmitri

Description

Lead halide perovskites nanocrystals (LHP NCs) are a recent novel material of ‘high-defect tolerance’ that has been synthesized which have provided a new platform for opto-electronic devices, such as photovoltaics and light-emitting diodes. Development of these materials for commercial devices requires a thorough understanding of their photo-physical properties. A comprehensive understanding of photo-physical properties involves studying the interplay between light-matter interactions, which produce photo-excited charge carriers and govern radiative recombination mechanism, carrier-lattice interactions, which play a dominate role in non-radiative dynamics such as hot-carrier cooling and recombination, and the NC surface chemistry which plays an important role in passivating surface sites which can potentially act as non-radiative recombination centers. In chapter 1 a review of the photo-physical phenomena and electronic processes which occur in materials is established and the motivation for incorporating nanomaterials into opto-electronic devise is provided. Chapter 2 describes in formal details the theoretical methods used to compute electronic structure, light-matter interactions, and carrier-lattice interactions are. Chapter 3 overviews simple physical models, such as particle-in-a-box photo-physics and two-level Redfield theory, which give intuition on how to understand the results of the research. Finally chapters 4-7 are devoted to original research on charge-carrier dynamics within a LHP NC atomistic model as free carriers, bound polarons, in the presence of surface defects, and finally in the presence of transition metal dopants. Chapter 4 provides computational evidence of slow electron cooling due to strong electronic confinement and large spin-orbit coupling contributed from Pb2+ 6p orbitals. Chapter 5 considers the effect of polaron formation on hot-carrier dynamics with the prediction of low efficiency polaron infrared photoluminescence. Chapter 6 provides mechanism for ‘defect tolerance’ due to bright electron surface trap states that form due to polaron reorganization. Chapter 7 models dual exciton-dopant luminescence due to Mn2+ doping.

Rights

NDSU policy 190.6.2

Rights Link

https://www.ndsu.edu/fileadmin/policy/190.pdf

Handle Identifier

https://hdl.handle.net/10365/32632

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