應用於光感測器之AgInSe2量子點的合成與鑑定 & 室溫一步合成錫鈣鈦礦奈米板發光材料

Synthesis and characterization of AgInSe2 quantum dot for photodetector & One step, room temperature synthesis of tin perovskite nanoplate of photoluminescence material

陳旻億(Min-Yi Chen)

指導教授 ： 周必泰

國立臺灣大學/理學院/化學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201704048

摘要

我們嘗試以AgInSe2量子點這種三元半導體作為光感測器的吸收層，利用其塊材能隙，Eg = 1.19~1.24 eV，吸收可包含可見光至近紅外光的範圍，使應用面更多元。量子點不僅擁有高吸收係數、高量子效率以及放光穩定等特性，還有製作成本低的優勢，在量產及未來商業應用上有極大的潛能。除此之外，為求環境保護及永續發展，尋找低毒性材料也是一項重要課題，使用AgInSe2便可符合此一要求。
利用高溫油相合成AgInSe2量子點，並透過配體置換的手法將長碳鏈配體(oleic acid, oleylamine 和 1-dodecanethiol)換成短碳鏈(3-mercaptopropionic acid)之配體來使載子遷移率提高，以期優化元件之效能。

我們利用過飽和析出的方式得到高量子效率的二維錫鈣鈦礦奈米板，其化學組成為PEA2SnX4(PEA=C6H5(CH2)2NH3, X = Br, I)。藉由調控鹵素組成，來得到不同的放光波長位置，其範圍可從550 nm(PEA2SnBr4)到640 nm (PEA2SnI4)，量子效率為0.10~6.26%，半高寬則為36~80 nm。我們發現在合成過程中，在反溶液當中加入羧酸做為添加劑，可以有效阻止錫二價氧化成錫四價，避免缺陷產生。因此，可以進一步提高奈米板的量子效率及穩定性。除此之外，加入添加劑這種作法還能應用在其他類似的系統，L2MX4，其中L = BA, OA (BA= CH3(CH2)3NH3+, OA=CH3(CH2)7NH3+)。結果可證明量子效率及波長可調性都有所提升。

關鍵字

二硒化銀銦 ； 量子點 ； 錫鈣鈦礦 ； 二維 ； 奈米

並列摘要

We tried to use ternary semiconductor – AgInSe2 quantum dot as absorbing layer in photodetector. With a bulk bandgap energy of 1.19~1.24 eV, AgInSe2 can effectively absorb light from visible light to near infrared, which is expected to have variety applications in optoelectronic fields. Quantum material has the advantages of its high absorption coefficient, high quantum yield, photo irradiation stability and low-cost solution-based fabrication techniques for large-scale production. Besides, searching low-toxicity material is also a big issue for enviromental protection. To sum up, AgInSe2 is a suitable material to meet these requirements.
AgInSe2 quantum dots were synthesized by using hot injection method. After synthesis, we performed ligand exchange to substitude ligands from long-chain ligands(oleic acid, oleylamine and 1-dodecanethiol) to short-chain one (3-mercaptopropionic acid) on the surface of quantum dots. By doing this, the carrier mobility can be boost and hence should improve the efficiency of photodetector device.

Here, we use recrystallization method to synthesis highly luminescent 2D tin-perovskite nanoplates with chemical formula of PEA2SnX4 (PEA=C6H5(CH2)2NH3, X = Br, I). Upon mixing iodo- and bromo- precursors, the emission peak wavelength was successfully tuned from 550 nm (PEA2SnBr4) to 640 nm (PEA2SnI4) with emission quantum yield in between 0.10~6.26% and full width at half maximum (FWHM) of 36~80 nm. During the synthesis, antisolvent with additive such as aliphatic acid was found to play a vital role to reduce tin perovskite defect density and hence boost the emission intensity and stability of tin-perovskite nanoplates. Besides, the method of adding additive to antisolvent can be applied to analogous system L2MX4 where L = BA, OA (BA= CH3(CH2)3NH3+, OA=CH3(CH2)7NH3+). The results confirmed that emission quantum yield and tunability has a great advance by adding additive.

並列關鍵字

AgInSe2 ； quantum dot ； tin perovskite ； PEA2SnI4 ； nano ； 2D

參考文獻

1. Roduner, E., Size matters: why nanomaterials are different. Chem Soc Rev 2006, 35 (7), 583-92.

2. Alivisatos, A. P., Perspectives on the Physical Chemistry of Semiconductor Nanocrystals. The Journal of Physical Chemistry 1996, 100 (31), 13226-13239.

3. Chou, K. F.; Dennis, A. M., Forster Resonance Energy Transfer between Quantum Dot Donors and Quantum Dot Acceptors. Sensors (Basel) 2015, 15 (6), 13288-325.

4. Takagahara, T., Effects of dielectric confinement and electron-hole exchange interaction on excitonic states in semiconductor quantum dots. Physical Review B 1993, 47 (8), 4569-4584.

5. Zillner, E.; Fengler, S.; Niyamakom, P.; Rauscher, F.; Köhler, K.; Dittrich, T., Role of Ligand Exchange at CdSe Quantum Dot Layers for Charge Separation. The Journal of Physical Chemistry C 2012, 116 (31), 16747-16754.