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Title: Photo-physics of light amplification in lead halide perovskites
Authors: Tay, Eugene Yong Kang
Keywords: Science::Physics
Issue Date: 2020
Publisher: Nanyang Technological University
Source: Tay, E. Y. K. (2020). Photo-physics of light amplification in lead halide perovskites. Doctoral thesis, Nanyang Technological University, Singapore.
Abstract: Low temperature solution-processed Organic-Inorganic Hybrid lead-halide Perovskites (OIHPs) nanocrystals (NCs) are new and emerging class of semiconducting materials that possesses high quantum yields (PLQY), large linear and non-linear absorption cross-sections, tunable emission wavelength via facile halide substitutions/exchanges. These properties make OIHP NCs the ideal candidate for light-emitting applications such as LEDs and lasing. Although preliminary reports showed a consistent trend of low (sub μJcm−2) ASE and lasing thresholds, these NC ensembles suffer from ambient air and moisture attacks, causing degradation and inevitably imposes stringent storage and operation conditions. Furthermore, the main fundamental photo-physics behind its optical gain is still not well understood. Therefore, in this thesis, we focus on (I) proposing a synthetic treatment during the Ligand-Assisted RePrecipitation (LARP) of Methyl Ammonium Lead Bromide (CH3NH3PbBr3) NCs in order to improve its surface passivation, (II) using Photoluminescence (PL) and Time-Resolved Photoluminescence (TR-PL) spectroscopy to characterize its ASE/lasing properties and (III) elucidating its carrier dynamics leading to population inversion and subsequently light amplification via spin-dependent Pump-Probe techniques. Specifically, we show that the bound excitons (BX) in CH3NH3PbBr3 NCs play a crucial role in the formation of zero-spin biexcitons (XX) with low biexciton binding energies (EBXX ~ 20meV), which are responsible for intrinsically spin-unpolarized optical gain mechanisms.
DOI: 10.32657/10356/144521
Schools: School of Physical and Mathematical Sciences 
Rights: This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:SPMS Theses

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