Browsing by Author "Huang, Hsiu-Ying"

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Coordination-induced emission enhancement in gold-nanoclusters with solid-state quantum yields up to 40% for eco-friendly, low-reabsorption nano-phosphors
(2019-03-11)
Huang, Hsiu-Ying
;
Cai, Kun-Bin
;
Talite, Maria Jessabel
;
Chou, Wu-Ching
;
Chen, Po-Wen
Colloidal quantum dots (CQDs) have gained much attention as light-emitting materials for light-conversion nano-phosphors and luminescent solar concentrators. Unfortunately, those CQDs involve toxic heavy metals and frequently need to be synthesized in the hazardous organic solvent. In addition, they suffer from severe solid-state aggregation-induced self-quenching and reabsorption losses. To address these issues, here we prepare Zn-coordinated glutathione-stabilized gold-nanocluster (Zn-GSH-AuNCs) assemblies without involving heavy metals and organic solvent. Unlike GSH-AuNCs dispersed in an aqueous solution with poor photoluminescence quantum yields (PL-QYs, typically similar to 1%), those Zn-GSH-AuNCs powders hold high solid-state PL-QYs up to 40 +/- 5% in the aggregated state. Such Zn-induced coordination-enhanced emission (CEE) is attributed to the combined effects of suppressed non-radiative relaxation and enhanced charge-transfer interaction. In addition, they also exhibit a large Stokes shift, thus mitigating both aggregation-induced self-quenching and reabsorption losses. Motivated by these photophysical properties, we demonstrated white-light emission from all non-toxic, aqueous-synthesis nano-materials.
Greener Luminescent Solar Concentrators with High Loading Contents Based on in Situ Cross-Linked Carbon Nanodots for Enhancing Solar Energy Harvesting and Resisting Concentration Induced Quenching
(2018-10-10)
Talite, Maria Jessabel
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Huang, Hsiu-Ying
;
Wu, Yao-Hsuan
;
Sena, Princess Genevieve
;
Cai, Kun-Bin
A luminescent solar concentrator (LSC) is composed of loaded luminophores and a waveguide that can be employed to harvest and concentrate both direct and diffused sunlight for promising applications in solar windows. Thus far, most of efficient LSCs still relied on the heavy-metal-containing colloidal quantum dots (CQDs) dispersed into a polymer matrix with a very low loading (typically <1 wt %). Such low-loading constraint is required to mitigate the concentration induced quenching (CIQ) and maintain high optical quality and film uniformity, but this would strongly reduce the light absorbing efficiency. To address all issues, greener LSCs with high loading concentration were prepared by in situ cross-linking organosilane-functionalized carbon nanodots (Si-CNDs), and their photophysical properties relevant to LSC operation were studied. The PL emission is stable and does not suffer from the severe CIQ effect for cross-linked Si-CNDs even with 25 wt % loadings, thus exhibiting high solid-state quantum yields (QYs) up to 45 +/- 5% after the calibration of the reabsorption losses. Furthermore, such LSCs can still hold high optical quality and film uniformity, leading to low scattering losses and high internal quantum efficiency of similar to 22%. However, the reabsorption losses need to be further addressed to realize large-area LSCs based on earth-abundant, cost-effective CNDs.
Visible-Transparent Luminescent Solar Concentrators Based on Carbon Nanodots in the Siloxane Matrix with Ultrahigh Quantum Yields and Optical Transparency at High-Loading Contents
(2020-01-16)
Talite, Maria Jessabel
;
Huang, Hsiu-Ying
;
Cai, Kun-Bin
;
Co, King Chester Capinig
;
Santoso, Phoa Adelina Cynthia
Visible-transparent luminescent solar concentrators (VT-LSCs) can be integrated with solar cells for designing solar glasses. Recently, rare-earth complexes, semiconductor nanocrystals, and carbon nanodots (CNDs) have been applied in developing VT-LSCs. However, several challenges still existed, such as quantum yields (QYs) at high-loading contents, scattering/reabsorption losses, and stability. Here, highly luminescent and visible-transparent composites based on organosilane-functionalized CNDs (Si-CNDs) cross-linked in the siloxane matrix were prepared. The composites with a high-loading content (similar to 10 wt %) possess ultrahigh QYs of similar to 94% due to surface passivation, cross-linking-enhanced emission, and negligible inter-CND energy transfer. Moreover, they still appear exceptionally transparent and, thus, are suitable for VT-LSCs. Eco-friendly VT-LSCs without colored tinting were fabricated, yielding high internal and external quantum efficiencies of similar to 66% and similar to 3.9%. Our demonstration would pave a bright way for the utilization of eco-friendly VT-LSCs in solar glasses.