三重陽離子鈣鈦礦與過渡金屬二硫化物量子點新型奈米材料之合成與鑑定

由於各種新型奈米材料在物理、化學和光電特性方面表現出非凡獨特且有益的特性，因此得到了各界廣泛的研究。透過在合成和製造技術中的各種方法，其用於電子、醫學和其他相關領域的可能性是廣泛的。從這些奈米材料中，三重陽離子鈣鈦礦材料和過渡金屬二硫化物量子點的出現引起了人們的極大興趣，並且正在積極研究以獲得其可大規模應用的可能性。鈣鈦礦結構（ABX3）材料在遵循Goldschmidt公差係數的前提下可靈活地設計其A、B和X元素位置。使該材料在結構和環境方面均能夠穩定於一般環境條件下。在本研究中，通過研究和分析鈣鈦礦太陽能電池的最佳製備條件，特別是對三重陽離子鈣鈦礦進行了複雜的研究。本研究研究了添加反溶劑、陽離子含量、旋塗和熱退火條件等處理步驟的重要性，發現改善的三重陽離子鈣鈦礦太陽能電池的重要製造參數：通過兩階段轉速法，摻雜10％銫陽離子，在100°C下退火1小時。在該製程條件下，獲得了具有高表面覆蓋率的高純度薄膜，該薄膜的能量轉換效率為10.90％。在進一步了解三重陽離子鈣鈦礦的能力之後，我們可以調整該材料的特性，並在480 nm至750 nm之間獲得不錯的光致發光，並保持其純度，這使其成為其他光電元件的良好選擇。此外，黑色鈣鈦礦相可以在大氣條件下保持四個月，更展現了其穩定性。使用修改後的技術製造三重陽離子鈣鈦礦太陽能電池可以為更穩定的太陽能電池鋪路，這將對未來相關應用是有利的。過渡金屬二硫化物衍生物如二硫化鎢量子點與二硫化鉬量子點有特別的光學、物理和電子等性質，可應用於新型的元件。在這裡，我們用上而下的脈衝雷射削融法和微波輔助加熱法合成二硫化鎢量子點與二硫化鉬量子點。當二硫化鎢量子點加入二乙烯三胺與二硫化鉬量子點加入麩醯胺酸，發現這些量子點的吸收，光激螢光和光激螢光激發都增強。此外，我們在氨基官能基化的二硫化鉬量子點中，觀察到Frenkel型的激子離域化，發現改變量子點濃度可控制Davydov分裂，最多可達850 meV，並可調節激子離域長度，最長的激子離域長度為39個量子點。此外，我們在加麩醯胺酸的二硫化鎢量子點進行電壓-電流量測，觀察到負微分電阻的現象。由改變空氣量和相對濕度的條件，發現在氧氣和氮氣環境下沒有負微分電阻現象，因此空氣中的水分子具有關鍵的角色。我們提出一模型來解釋負微分電阻現象:當外加電壓改變方向時，可能水分子電偶極矩無法立刻轉向因而抵消外加電場，產生了負微分電阻現象。研究上述的各種機制，有助於過渡金屬二硫化物的物理現象了解與其在光電元件的應用。

關鍵字

三重陽離子；鈣鈦礦；激子離域； Davydov分裂；胺?官能團化；負微分電阻（NDR）

並列摘要

Different new types of nanomaterials are widely studied because they manifest extraordinary, distinct, and beneficial properties in terms of their physical, chemical, and optoelectronic properties. By using a different approach in synthesis and fabrication techniques, the possibility of which it can be utilized for different applications in electronics, medicine, and other fields are broad. From these nanomaterials, the emergence of triple cation perovskite materials and transition metal dichalcogenide quantum dots (TMD QDs) have gained rapid interest and are being investigated to extract all the properties that it can offer for large-scale applications. The flexibility of the perovskite materials to engineer its A- , B- and X-site while obeying the Goldschmidt tolerance factor made the material to be structurally and environmentally stable at ambient conditions. Here, a triple cation perovskite was intricately investigated by finding and analyzing an optimum fabrication condition for an effective perovskite solar cell (PSC). Emphasizing the significance of processing steps like the addition of anti-solvent, cation contents, spin-coating, and thermal annealing conditions, it was found out that the improved fabrication parameter of triple cation PSCs employs 10% cesium cation content via two-step spin-coating with the addition of anti-solvent annealed under 100 °C for 1 hour. In this process, a high purity thin film with full surface coverage was obtained which measures a power conversion efficiency (PCE) of 10.90%. With further understanding of the capacity of triple cation perovskites, it was examined that the material can be tuned its properties and expand its photoluminescence from 480 nm to 750 nm in electromagnetic spectrum maintaining its purity which makes it a good candidate for additional optoelectronic applications. Also, its stability has been tested by sustaining the black perovskite phase of the sample for four months even after exposure to atmospheric conditions. Using the modified techniques in fabricating the triple cation PSCs can pave the way to more stable solar cells which will be beneficial for future and upscale applications. The synthesis of TMD materials like MoS2 and WS2 to quantum dot (QD) derivatives have become facile and effective which unravel many optical, physical, and electronics mechanisms for creating novel devices. Here, a top-down approach was used for synthesizing MoS2 and WS2 QDs via pulse laser ablation (PLA) and microwave-assisted treatment. By introducing amino-functionalized diethylenetriamine (DETA) in MoS2 QDs and glutamine (GLN) in WS2 QDs, the enhancement in terms of its absorption, photoluminescence (PL) and PL excitation were noteworthy. Moreover, a Frenkel-type exciton delocalization that describes a spatial extension of the exciton spreads over aggregates was observed in amino-functionalized MoS2 QDs. Through this, a large Davydov splitting up to ~850 meV and an additional exchange narrowing with an exciton delocalization length of 39 QDs were measured and modulated by controlling the QD concentration. In addition, negative differential resistance (NDR) via GLN-functionalized WS2 QDs were observed in current-voltage (I-V) characteristics. Due to measurements of I-V curves by changing the exposure time in air and relative humidity, it was found out that water molecules in air greatly contributes to the NDR since no NDR was measured under O2 and N2 environment. We proposed a model to explain the NDR in GLN-functionalized WS2 QDs. Due to the hydrophilicity of GLN, water molecules in air can be easily trapped on the surface of QDs. When the direction of applied electric field was changed the induced dipole of water molecules on the surface opposes the applied electric field and resulted in NDR phenomenon. Investigating these different mechanisms in TMD QDs brought promising opportunities for the discovery of advantageous physical phenomena for the developing devices.

並列關鍵字

triple cation ； perovskite ； exciton delocalization ； Davydov splitting ； amino-functionalized ； negative differential resistance (NDR)

參考文獻

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三重陽離子鈣鈦礦與過渡金屬二硫化物量子點新型奈米材料之合成與鑑定

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