探討具胺基酸摻雜氧化石墨烯量子點的光電特性

Optical and Electrical Properties of Graphene Oxide Quantum Dots with Amino Acid

周芸瑄(Yun-Syuan Chou)

指導教授 ： 沈志霖

中原大學/理學院/物理研究所/碩士(2018年)

https://doi.org/10.6840/cycu201800489

摘要

本論文利用脈衝雷射消融法合成出具不同胺基酸摻雜的氧化石墨烯量子點，當於UV紫外燈照射下時表現出高強度的藍色螢光。透過紫外-¬¬可見吸收、光激螢光、時間解析光激螢光、電子顯微鏡和X射線光電子能譜探討胺基酸摻雜氧化石墨烯量子點的結構及其光學特性。其中組胺酸摻雜的氧化石墨烯量子點平均粒徑大小為4.6 ± 0.04 nm，而光激螢光強度比原始的氧化石墨烯量子點增強了約110倍，主要是摻雜後吡咯氮增加而提升其螢光強度。
另外，我們進一步的探討具胺基酸摻雜氧化石墨烯的電學特性，發現具賴胺酸摻雜的氧化石墨烯量子點呈現出最佳的導電性質。利用紫光雷射進行光電流量測，發現摻雜氧化石墨烯量子點具有負光電導行為。更進一步測量其響應度及光響應時間，發現賴胺酸摻雜的氧化石墨烯量子點有6833.3 nA·W-1的光響應度及較長的光響應時間。閘極電壓和汲極電流曲線圖表明賴胺酸摻雜氧化石墨烯量子點為P型半導體，載子遷移率為3.29 × 10-2 cm2·V-1·s-1。
再來於真空、氮氣、氧氣和空氣的環境下，以及利用不同波長的雷射光當作照射光源，觀察環境及照光後對胺基酸摻雜氧化石墨烯量子點的電性影響。我們提出負光電導其機制主要來自空氣中的水分子會吸附到氧化石墨烯量子點的表面，照光後脫附所導致的行為。

關鍵字

量子點；雷射消融法；氧化石墨烯；胺基酸；負光電導效應

並列摘要

In this research, pulsed laser ablation was used to synthesize graphene oxide quantum dots (GOQDs) doped with different amino acids. When exposed to Ultraviolet (UV)light, amino acid doped-GOQDs display blue photoluminescence (PL) with high-intensity. UV-vis absorption, PL, time-resolved PL (TRPL), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were used to investigate the effect of amino acid doping on the structure and optical properties of GOQDs. The average particle size of the histidine-doped GOQDs is 4.6 ± 0.04 nm with a PL intensity of about 110 times stronger than that of the undoped GOQDs, mainly due to the increase of the pyrrolic-nitrogen configuration within GOQDs structure after doping.
In addition, the electrical properties of amino acid doped-GOQDs were also studied. It is found that GOQDs doped with lysine showed highest conductivity compared to other amino-acid doped GOQDs in this research. In addition, electrical property of amino acid-doped GOQDs was observed. Here, the electrical response of the amino acid-doped GOQDs versus environment and illumination were observed. On the basis of environmental effects on electrical response, the amino acid-doped GOQDs were subjected in vacuum and air as well as in nitrogen and oxygen. The use of laser excitation of different wavelengths as the light source was utilized for investigation of effect of illumination wavelength versus electrical response. Photoelectric flow measurement was performed using a violet laser (405 nm) and demonstrated a negative photoconductivity (NPC) for amino acid doped-GOQDs. The responsivity and photoresponse time were also measured. It was found that the lysine-doped GOQDs has a photoresponsivity of 6833.3 nA·W-1 with a photoresponse time of 49.5 s. The curves of the gate voltage and the drain current reveal that the lysine-doped GOQDs are p-type semiconductors with carrier mobility of 3.29 × 10-2 cm2·V-1·s-1.
With regards, we propose that the mechanism of NPC is mainly due to the fact that water molecules in the air will adsorb on the surface of the GOQDs and de-absorb after irradiation.

並列關鍵字

Guantum dots；Laser ablation；Graphene oxide；Amino acid；Negative photoconductivity

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