環保金奈米團簇光物理性質探討及太陽能聚光板應用

Investigation of photophysical properties of greener gold nanoclusters and their applications in luminescent solar concentrators

蔡錕斌(Kun-Bin Cai)

指導教授 ： 院繼祖

中原大學/理學院/物理研究所/碩士(2018年)

https://doi.org/10.6840/cycu201800583

摘要

綠能意識提升，太陽能聚光板可以接收直射及散射的太陽光，這就是智慧窗戶的重要性。近幾年來，高效率的太陽能聚光板都是利用擁有異質結構的重金屬膠體量子點所製作的。不幸的，這些量子點都含有毒元素及需在有機溶劑裡合成。此外，它們都受到再吸收的損失及在固體中的聚集誘導螢光淬滅的現象，這些都是需要解決的問題才能實現大面積的太陽能聚光板。環保金奈米團簇可以直接在水溶液合成，且它的獨特的螢光光學適合應用在太陽能聚光板上引起我們的興趣，它的發光模式具有大的斯托克斯位移，這有利於在太陽能聚光板中再吸收的降低，不過，它本身的低量子產率影響它在太陽能聚光板中的性能。
在本論文，研究利用鋅離子交聯金奈米團簇，探討它在水溶液及固體中的光學特性，我們發現當鋅-金奈米團簇的pH值為4的時候，相較於金奈米團簇本身的低量子產率(~0.4%)，它提高了量子產率到達7%且也增大的斯托克斯位移的程度。更重要的是，鋅-金奈米團簇在固體中量子效率高達52%，這是因為抑制了非輻射覆合途徑及改變了不同的三重態放光。因為它優異的光學特性，選用鋅-金奈米團簇pH=4製作綠能太陽能聚光板，由於低再吸收及在固體中的高量子產率，鋅-金奈米團簇pH=4綠能太陽能聚光板的內部量子效率高達33%，可以與含有有毒元素的膠體量子點所製作的太陽能聚光板相比拚。

關鍵字

金奈米糰簇 ； 太陽能聚光板

並列摘要

A luminescent solar concentrator (LSC) can be used to concentrate both direct and diffused sunlight, which is the main component of solar windows. Recently, efficient LSCs based on heavy-metal colloidal quantum dots (CQDs) with carefully designed heterostructures have been demonstrated. Unfortunately, those CQDs involve toxic elements and need to be synthesized in the hazardous organic solvent. In addition, they still suffer from reabsorption losses and solid-state concentration-induced quenching, which need to be addressed for realizing large-area greener LSCs. Eco-friendly gold nanoclusters (AuNCs), which can be directly synthesized in an aqueous solution have attracted our attention due to their unique PL emission for LSC applications. The PL emission of GSH-AuNCs hold large Stokes shift, which would be beneficial for reducing the reabsorption losses in LSCs, however, the extremely low PL quantum yields (PL-QYs) significantly hinder their performance in LSCs.
In this thesis, the photophysical properties were investigated for Zn2+-induced cross-linked GSH-AuNCs (Zn-GSH-AuNCs) in solution and in the solid state. We found that the Zn-GSH-AuNCs at pH 4 exhibit enhanced PL-QYs of ~7% and enlarged Stokes shifts as compared with that of as-synthesized GSH-AuNCs (PL-QY~0.4%). More importantly, Zn-GSH-AuNCs embedded in a rigid polymer matrix hold extremely high solid-state PL-QYs up to ~53% along with blue-shifted PL spectrum due to suppression of non-radiative relaxation and switching of the emissive triplet states. Owing to appealing photophysical properties, greener LSCs were fabricated based on those Zn-GSH-AuNCs. The LSCs exhibit high internal quantum efficiency of ~33% thanks to low reabsorption losses and high solid-sate PL-QYs, which is already comparable with that of the LSCs based on conventional toxic CQDs.

並列關鍵字

gold nanoclusters ； luminescent solar concentrators

參考文獻

[1] M.G. Debije, P.P.C. Verbunt, Thirty Years of Luminescent Solar Concentrator Research: Solar Energy for the Built Environment, Advanced Energy Materials, 2 (2012) 12-35.

[2] G. Luo, H. Wu, Organic solar cells: Going green, Nature Energy, 1 (2016) 16001.

[3] B. Katherine, Quantum dots go on display, Nature, 493 (2013) 2.

[4] X. Gong, Z. Yang, G. Walters, R. Comin, Z. Ning, E. Beauregard, V. Adinolfi, O. Voznyy, E.H. Sargent, Highly efficient quantum dot near-infrared light-emitting diodes, Nature Photonics, 10 (2016) 253.

[5] Z. Wu, R. Jin, On the ligand's role in the fluorescence of gold nanoclusters, Nano Lett, 10 (2010) 2568-2573.