Abstract
Colloidal semiconductor nanocrystals (NCs) have undergone rapid development over the past two decades. Their solution-processable synthesis, narrow emission linewidth, and highly tunable optical properties have enabled a wide range of classical optoelectronic applications, including displays, lighting, and photovoltaics. Beyond their established role in conventional optoelectronics, recent advances have revealed the significant potential of colloidal NCs in quantum information science. Their strong oscillator strengths, discrete energy-level structures, and ligand-induced chiroptical responses create opportunities for quantum photonics and spintronics, positioning NCs as promising candidates for quantum information science.This thesis presents four projects that engineer the optoelectronic and chiroptical properties of colloidal NCs toward quantum information science. In Chapter 3, we developed a synthetic strategy for ultrasmall, strongly quantum-confined CsPbBr3 NCs with deep-blue emission, which served as efficient emitters in quantum dot light-emitting diodes. We further investigated their spin-decoherence dynamics, revealing an ultrafast timescale in the several-picosecond regime. In Chapter 4, we implemented a high-entropy alloying strategy to realize bright, stable single-photon emitters by incorporating multi-cations into CsPb(Br/Cl)3 NCs. The resulting high-entropy alloying NCs exhibited enhanced radiative recombination, suppressed nonradiative loss, and single-photon purity as high as 96% with minimal blinking at room temperature. In Chapter 5, we developed a liquid-phase ligand-exchange strategy using cysteine to induce chirality in AgBiS2 NCs. These NCs exhibited the highest dissymmetry factor reported for ligand-exchanged semiconductor NCs, arising from bidentate ligand coordination. Spin-dependent transport measurements confirmed chirality-induced spin selectivity, with spin polarization exceeding 85%, establishing AgBiS2 NCs as a promising lead-free spin-filter platform. In Chapter 6, we explored the spontaneous emergence of intrinsic chirality in CsPbBr3 NCs without chiral ligands. By introducing steric hindrance via racemic 4-methylbenzylammonium during growth, we observed time-resolved circular dichroism sign reversal and enhanced intrinsic chirality in CsPbBr3 NCs. Collectively, these studies open new design pathways for integrating colloidal NCs into quantum information platforms by engineering their optoelectronic and chiroptical properties.
| Date of Award | 2026 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Supervisor | Jonathan Eugene HALPERT (Supervisor) & Liang Guo (Supervisor) |
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