金屬鹵化物鈣鈦礦之合成、鑑定與應用

Metal Halide Perovskite: Synthesis, Characterization and Application

卡夏(Kashyap Dave)

指導教授 ： 劉如熹

國立臺灣大學/理學院/化學研究所/博士(2022年)

https://doi.org/10.6342/NTU202200466

摘要

含鉛之無機鹵化物鈣鈦礦材料因其高量子產率、發光波長可調性、高缺陷容忍性與窄半高寬之放射而受到光電元件相關之研究人員關注。儘管此材料具顯著之光學特性，然鉛所產生之毒性卻會實際影響生活中各個層面之應用，即使低濃度之鉛亦溶於水，會危害人體健康，此一缺點促使研究人員開始探索用於光電顯示器之無鉛鈣鈦礦材料。
本研究論文涵蓋三主題，一為經室溫再結晶方法提高CsPbBr3 奈米晶體之量子效率，二為合成應用於白光之無鉛雙鈣鈦礦材料Cs2AgInCl6，三為以Cs2AgInCl6 中之自陷激子能量轉移應用於光通訊。於主題一，本研究採用四種有機配體於再結晶法之實驗步驟合成高量子效率之CsPbBr3 奈米晶體，與傳統熱注射方法(45%)相比，此方法合成之量子效率高達83%。經自陷激子放射之寬帶放射為400 至800 nm，使無鉛雙鈣鈦礦材料Cs2AgInCl6 於此紫外光激發下呈現暖白光，然量子效率略差。為提高此材料之量子效率，於第二部分中則使用酸沉澱法合成摻雜鈉(Na) 、鉍(Bi) 與鉺(Er) 之Cs2AgInCl6 雙鈣鈦礦及其衍生物。將8%之Bi 摻雜於Cs2AgInCl6 系統中，可觀察其量子效率從2%上升至52.4%，光學鑑定中表明，於一般條件下此材料之自陷激子放射為白光，然於施加外部壓力下亦可觀測放射其原因為自由激子態。於第三部分中，Er3+摻雜於Cs2Ag0.4Na0.6In0.92Bi0.08Cl6 之系統中，應用於低能量損耗之光通訊。此雙鈣鈦礦材料增強自陷激子之放射，並觸發能量轉移至1540 nm 處Er 之放射(4I13/2→4I15/2)。

關鍵字

量子點 ； 雙鈣鈦礦 ； 自陷激子 ； 發光二極體

並列摘要

Inorganic lead halide perovskite structure gained attention among researchers in optoelectronics devices due to its high photoluminescence quantum yield (PLQY), easily tunable emission, high defect tolerance, and the narrow band with emission. Despite the remarkable properties, its toxic lead content is a constraining factor in the applicability of these materials in real-time applications. Even the low concentrations of lead are soluble in water, and it will affect the human body. This drawback urges the researchers to explore lead-free perovskite structures for optoelectronic applications. This research thesis contains three major parts as follows: enhancement in the quantum yield of CsPbBr3 nanocrystals by room temperature recrystallization method, synthesis of lead-free double perovskite Cs2AgInCl6 for white light emission, and self-trapped exciton (STE) based energy transfer in Cs2AgInCl6 for optical telecommunications. In the first part of the research, the tetra organic ligand-assisted recrystallization method is employed to synthesize CsPbBr3 nanocrystals and achieved PLQY of 83% in comparison to conventional hot injection (45%). Lead-free Cs2AgInCl6 exhibits warm white light due to the broadband emission (400–800 nm) via STE emission, but the PLQY is poor. To enhance the efficiency, we use an acid precipitation method to synthesize Cs2AgInCl6 double perovskite and its derivatives with sodium (Na), bismuth (Bi), and erbium (Er) in the second part. The PLQY of Cs2AgInCl6 increase from 2% to 52.4% by the doping of 8% Bi into Cs2AgInCl6 system. The detailed luminescence characterizations show that the white emission is because of STE emission at normal conditions, but the application of external pressure shows that the emission is because of the free exciton state. In the third part, we doped Er3+ in the Cs2Ag0.4Na0.6In0.92Bi0.08Cl6 system for the low loss optical telecommunication applications. This double perovskite system enhances self-trapped exciton emission, which triggers the energy transfer to Er (4I13/2→4I15/2) at 1540 nm.

並列關鍵字

quantum dots ； double perovskites ； self-trapped excitons ； light-emitting diodes

參考文獻

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