本研究以熱注入法合成紅綠色鈣鈦礦量子點並與藍光LED結合以開發廣色域與高演色性白光LED，分別應用於顯示器與照明元件。然而因量子點CsPbBr3本身容易有水解氧化及粉末狀態下會有發光效率大幅下降的問題，因此本論文將著重於改善此發光材料的水氧穩定性及提升量子效率。採取低溫合成下的相轉換及二氧化矽包覆製備綠紅色Cs4PbBr6/SiO2與Cs4Pb(Br0.4I0.6)6/SiO2粉末，量子效率由原先CsPbBr3/SiO2之31.41%提升至Cs4PbBr6/SiO2之45.87%；Cs4Pb(Br0.4I0.6)6/SiO2則為22.79%。
其中光強度提升之原因為：以低溫合成方式可使鈣鈦礦量子點產生相轉換之現象，由原先三維之CsPbBr3轉為零維Cs4PbBr6，由於此零維結構具有強量子侷限效應，可增加電子電洞輻射再結合的機率，因此可顯著提升發光效率。於本研究中也以螢光光譜儀、XRD、Decay time、XPS與熱穩定性量測，深入探討此相轉換現象對於發光材料之量子效率、晶體結構、發光機制、電子束縛能與熱淬滅現象造成之影響。
於元件端採取PMMA壓克力與矽膠封裝將Cs4PbBr6/SiO2與藍光LED結合製成純綠光元件，並比較兩者封裝方式之差異，可發現PMMA封裝雖具有較佳之元件穩定性，但其效率則有較低之現象。因此採用矽膠封裝將綠色Cs4PbBr6/SiO2、紅色Cs4Pb(Br0.4I0.6)6/SiO2粉末與藍光LED結合製備廣色域白光元件，可具有115%之NTSC標準色域覆蓋率，元件效率達51 lm/W皆高於傳統氮化物螢光粉與鎘量子點白光LED；並以商用黃色YAG螢光粉與紅色Cs4Pb(Br0.4I0.6)6/SiO2量子點粉末結合開發出具有極高演色性之白光照明設備，演色性由77提升至93，為相當高之改善效果且色溫也從5732K之冷白光下降至3828K之自然光，並具有38 lm/W的發光效率，皆優於許多量子點白光LED之元件特性。

To develop white light-emitting diodes (WLEDs) for displays with wide color gamut and lightings with high CRI, unlike phosphors and conventional quantum dots (QDs) such as CdSe, InP, CuInS2, all-inorganic perovksite QDs CsPbX3 (X=Cl, Br, I) were more superior candidate owing to excellent optoelectronic properties such as high quantum efficiency, narrow emission wavelength and tunable emission spectrum. However, the CsPbBr3 QDs in solid form had poor air-stability and severe decrease of quantum efficiency. These disadvantages were harmful to their practical applications. To overcome these drawbacks, in this work, we provided a new idea that zero-dimensional green-red perovskite QDs powders Cs4PbBr6 and Cs4Pb(Br0.4I0.6)6 with improved quantum efficiency and long lifetime could be successfully developed by silica-coated method and crystal phase transition in low-temperature synthesis. Then, we would proceed a series of detailed discussions on this phenomenon of phase transition and find the quantum efficiency in green powders could be significantly enhanced from 31.41% to 45.87% and red powders were 22.79%. Moreover, the as-prepared perovskite QDs powders and commercial YAG phosphors combined with blue chips were applied to high-quality WLEDs for lightings and displays. More importantly, the as-fabricated WLEDs for displays possessed 115% NTSC color gamut and luminous efficiency of 51 lm/W under 20mA driving current. On the other hand, the constructed WLEDs for high-power lightings would generate a warm white light with extremely high CRI of 92.8 and low CCT of 3828K under 350mA. Therefore, our proposed perovskite QDs powders had outstanding potential applications in WLEDs.

Key words：zero-dimensional inorganic perovskite quantum dots powders, capping structure, phase transition mechanisms, WLEDs devices with high CRI and wide color gamut

參考文獻
[1] E. Jang, S. Jun, H. Jang, J. Lim, B. Kim, and Y. Kim, “White‐light‐emitting diodes with quantum dot color converters for display backlights,” Advanced Materials, vol. 22, no. 28, pp. 3076-3080, 2010.
[2] L.-Y. Chen, W.-C. Cheng, C.-C. Tsai, J.-K. Chang, Y.-C. Huang, J.-C. Huang, and W.-H. Cheng, “Novel broadband glass phosphors for high CRI WLEDs,” Optics Express, vol. 22, no. 103, pp. A671-A678, 2014.
[3] B. P. Singh, S.-Y. Lin, H.-C. Wang, A.-C. Tang, H.-C. Tong, C.-Y. Chen, Y.-C. Lee, T.-L. Tsai, and R.-S. Liu, “Inorganic red perovskite quantum dot integrated blue chip: a promising candidate for high color-rendering in w-LEDs,” RSC Advances, vol. 6, no. 83, pp. 79410-79414, 2016.
[4] J. Zhou, F. Huang, H. Lin, Z. Lin, J. Xu, and Y. Wang, “Inorganic halide perovskite quantum dot modified YAG-based white LEDs with superior performance,” Journal of Materials Chemistry C, vol. 4, no. 32, pp. 7601-7606, 2016.
[5] X. Piao, T. Horikawa, H. Hanzawa, and K.-i. Machida, “Characterization and luminescence properties of Sr2Si5N8 : Eu2+ phosphor for white light-emitting-diode illumination,” Applied Physics Letters, vol. 88, no. 16, pp. 161908, 2006.
[6] 劉偉仁、姚中業、黃健豪、鍾淑茹、金風, “LED 螢光粉技術,” 五南出版, (2014).
[7] S. Guarnera, A. Abate, W. Zhang, J. M. Foster, G. Richardson, A. Petrozza, and H. J. Snaith, “Improving the long-term stability of perovskite solar cells with a porous Al2O3 buffer layer,” The Journal of Physical Chemistry Letters, vol. 6, no. 3, pp. 432-437, 2015.
[8] A. Fakharuddin, F. Di Giacomo, A. L. Palma, F. Matteocci, I. Ahmed, S. Razza, A. D’Epifanio, S. Licoccia, J. Ismail, and A. Di Carlo, “Vertical TiO2 nanorods as a medium for stable and high-efficiency perovskite solar modules,” ACS nano, vol. 9, no. 8, pp. 8420-8429, 2015.
[9] J. You, L. Meng, T.-B. Song, T.-F. Guo, Y. M. Yang, W.-H. Chang, Z. Hong, H. Chen, H. Zhou, and Q. Chen, “Improved air stability of perovskite solar cells via solution-processed metal oxide transport layers,” Nature nanotechnology, vol. 11, no. 1, pp. 75, 2016.
[10] Q. Luo, Y. Zhang, C. Liu, J. Li, N. Wang, and H. Lin, “Iodide-reduced graphene oxide with dopant-free spiro-OMeTAD for ambient stable and high-efficiency perovskite solar cells,” Journal of Materials Chemistry A, vol. 3, no. 31, pp. 15996-16004, 2015.
[11] A. Loiudice, S. Saris, E. Oveisi, D. T. Alexander, and R. Buonsanti, “CsPbBr3 QD/AlOx inorganic nanocomposites with exceptional stability in water, light, and heat,” Angewandte Chemie International Edition, vol. 56, no. 36, pp. 10696-10701, 2017.
[12] M. I. Saidaminov, J. Almutlaq, S. Sarmah, I. Dursun, A. A. Zhumekenov, R. Begum, J. Pan, N. Cho, O. F. Mohammed, and O. M. Bakr, “Pure Cs4PbBr6: highly luminescent zero-dimensional perovskite solids,” ACS Energy Letters, vol. 1, no. 4, pp. 840-845, 2016.
[13] C. de Weerd, J. Lin, L. Gomez, Y. Fujiwara, K. Suenaga, and T. Gregorkiewicz, “Hybridization of single nanocrystals of Cs4PbBr6 and CsPbBr3,” The Journal of Physical Chemistry C, vol. 121, no. 35, pp. 19490-19496, 2017.
[14] E. Schubert, “Light-emitting diodes New York Cambridge,” 2006.
[15] 劉如熹, and 劉宇桓, 發光二極體用氧氮螢光粉介紹: 全華科技圖書, 2006.
[16] R. Kubo, “Electronic properties of metallic fine particles. I,” Journal of the Physical Society of Japan, vol. 17, no. 6, pp. 975-986, 1962.
[17] 詹亭軾, “橘紅色鹵化鋁酸鹽類螢光粉之合成與高演色性白光發光二極體新型封裝技術探討及開發,” 成功大學電機工程學系學位論文, 2016.
[18] 楊俊英, "電子產業用螢光材料之調查," 工研院, 1992.
[19] D. Chen, Y. Zhou, W. Xu, J. Zhong, Z. Ji, and W. Xiang, “Enhanced luminescence of Mn4+: Y3Al5O12 red phosphor via impurity doping,” Journal of Materials Chemistry C, vol. 4, no. 8, pp. 1704-1712, 2016.
[20] D. Bera, L. Qian, S. Sabui, S. Santra, and P. H. Holloway, “Photoluminescence of ZnO quantum dots produced by a sol–gel process,” Optical Materials, vol. 30, no. 8, pp. 1233-1239, 2008.
[21] A. I. Ekimov, and A. A. Onushchenko, “Quantum size effect in three-dimensional microscopic semiconductor crystals,” Jetp Lett, vol. 34, no. 6, pp. 345-349, 1981.
[22] C. Murray, D. J. Norris, and M. G. Bawendi, “Synthesis and characterization of nearly monodisperse CdE (E= sulfur, selenium, tellurium) semiconductor nanocrystallites,” Journal of the American Chemical Society, vol. 115, no. 19, pp. 8706-8715, 1993.
[23] M. A. Hines, and P. Guyot-Sionnest, “Synthesis and characterization of strongly luminescing ZnS-capped CdSe nanocrystals,” The Journal of Physical Chemistry, vol. 100, no. 2, pp. 468-471, 1996.
[24] B. J. Druker, M. Talpaz, D. J. Resta, B. Peng, E. Buchdunger, J. M. Ford, N. B. Lydon, H. Kantarjian, R. Capdeville, and S. Ohno-Jones, “Efficacy and safety of a specific inhibitor of the BCR-ABL tyrosine kinase in chronic myeloid leukemia,” New England Journal of Medicine, vol. 344, no. 14, pp. 1031-1037, 2001.
[25] A. Zaban, O. Mićić, B. Gregg, and A. Nozik, “Photosensitization of nanoporous TiO2 electrodes with InP quantum dots,” Langmuir, vol. 14, no. 12, pp. 3153-3156, 1998.
[26] L. Li, T. J. Daou, I. Texier, T. T. Kim Chi, N. Q. Liem, and P. Reiss, “Highly luminescent CuInS2/ZnS core/shell nanocrystals: cadmium-free quantum dots for in vivo imaging,” Chemistry of Materials, vol. 21, no. 12, pp. 2422-2429, 2009.
[27] L. Protesescu, S. Yakunin, M. I. Bodnarchuk, F. Krieg, R. Caputo, C. H. Hendon, R. X. Yang, A. Walsh, and M. V. Kovalenko, “Nanocrystals of cesium lead halide perovskites (CsPbX3, X= Cl, Br, and I): novel optoelectronic materials showing bright emission with wide color gamut,” Nano letters, vol. 15, no. 6, pp. 3692-3696, 2015.
[28] A. Kojima, K. Teshima, Y. Shirai, and T. Miyasaka, “Organometal halide perovskites as visible-light sensitizers for photovoltaic cells,” Journal of the American Chemical Society, vol. 131, no. 17, pp. 6050-6051, 2009.
[29] F. Zhang, H. Zhong, C. Chen, X.-g. Wu, X. Hu, H. Huang, J. Han, B. Zou, and Y. Dong, “Brightly luminescent and color-tunable colloidal CH3NH3PbX3 (X= Br, I, Cl) quantum dots: potential alternatives for display technology,” ACS nano, vol. 9, no. 4, pp. 4533-4542, 2015.
[30] X. Li, Y. Wu, S. Zhang, B. Cai, Y. Gu, J. Song, and H. Zeng, “CsPbX3 Quantum Dots for Lighting and Displays: Room‐Temperature Synthesis, Photoluminescence Superiorities, Underlying Origins and White Light‐Emitting Diodes,” Advanced Functional Materials, vol. 26, no. 15, pp. 2435-2445, 2016.
[31] Q. A. Akkerman, V. D’Innocenzo, S. Accornero, A. Scarpellini, A. Petrozza, M. Prato, and L. Manna, “Tuning the optical properties of cesium lead halide perovskite nanocrystals by anion exchange reactions,” Journal of the American Chemical Society, vol. 137, no. 32, pp. 10276-10281, 2015.
[32] W. Chen, J. Hao, W. Hu, Z. Zang, X. Tang, L. Fang, T. Niu, and M. Zhou, “Enhanced stability and tunable photoluminescence in perovskite CsPbX3/ZnS quantum dot heterostructure,” Small, vol. 13, no. 21, pp. 1604085, 2017.
[33] S. Huang, Z. Li, L. Kong, N. Zhu, A. Shan, and L. Li, “Enhancing the stability of CH3NH3PbBr3 quantum dots by embedding in silica spheres derived from tetramethyl orthosilicate in “waterless” toluene,” Journal of the American Chemical Society, vol. 138, no. 18, pp. 5749-5752, 2016.
[34] M. Yang, H.-s. Peng, F.-l. Zeng, F. Teng, Z. Qu, D. Yang, Y.-q. Wang, G.-x. Chen, and D.-w. Wang, “In situ silica coating-directed synthesis of orthorhombic methylammonium lead bromide perovskite quantum dots with high stability,” Journal of colloid and interface science, vol. 509, pp. 32-38, 2018.
[35] C. Sun, Y. Zhang, C. Ruan, C. Yin, X. Wang, Y. Wang, and W. W. Yu, “Efficient and Stable White LEDs with Silica‐Coated Inorganic Perovskite Quantum Dots,” Advanced Materials, vol. 28, no. 45, pp. 10088-10094, 2016.
[36] D. N. Dirin, L. Protesescu, D. Trummer, I. V. Kochetygov, S. Yakunin, F. Krumeich, N. P. Stadie, and M. V. Kovalenko, “Harnessing defect-tolerance at the nanoscale: Highly luminescent lead halide perovskite nanocrystals in mesoporous silica matrixes,” Nano letters, vol. 16, no. 9, pp. 5866-5874, 2016.
[37] H. C. Wang, S. Y. Lin, A. C. Tang, B. P. Singh, H. C. Tong, C. Y. Chen, Y. C. Lee, T. L. Tsai, and R. S. Liu, “Mesoporous Silica Particles Integrated with All‐Inorganic CsPbBr3 Perovskite Quantum‐Dot Nanocomposites (MP‐PQDs) with High Stability and Wide Color Gamut Used for Backlight Display,” Angewandte Chemie International Edition, vol. 55, no. 28, pp. 7924-7929, 2016.
[38] W. Xu, Z. Cai, F. Li, J. Dong, Y. Wang, Y. Jiang, and X. Chen, “Embedding lead halide perovskite quantum dots in carboxybenzene microcrystals improves stability,” Nano Research, vol. 10, no. 8, pp. 2692-2698, 2017.
[39] Y. Wei, X. Deng, Z. Xie, X. Cai, S. Liang, P. a. Ma, Z. Hou, Z. Cheng, and J. Lin, “Enhancing the stability of perovskite quantum dots by encapsulation in crosslinked polystyrene beads via a swelling–shrinking strategy toward superior water resistance,” Advanced Functional Materials, vol. 27, no. 39, pp. 1703535, 2017.
[40] Y. Zhang, M. I. Saidaminov, I. Dursun, H. Yang, B. Murali, E. Alarousu, E. Yengel, B. A. Alshankiti, O. M. Bakr, and O. F. Mohammed, “Zero-dimensional Cs4PbBr6 perovskite nanocrystals,” The Journal of Physical Chemistry Letters, vol. 8, no. 5, pp. 961-965, 2017.
[41] X. Wang, X. Yan, W. Li, and K. Sun, “Doped quantum dots for white‐light‐emitting diodes without reabsorption of multiphase phosphors,” Advanced Materials, vol. 24, no. 20, pp. 2742-2747, 2012.
[42] I. S. Sohn, S. Unithrattil, and W. B. Im, “Stacked quantum dot embedded silica film on a phosphor plate for superior performance of white light-emitting diodes,” ACS applied materials & interfaces, vol. 6, no. 8, pp. 5744-5748, 2014.
[43] Y. H. Song, S. H. Choi, J. S. Yoo, B. K. Kang, E. K. Ji, H. S. Jung, and D. H. Yoon, “Design of long-term stable red-emitting CsPb(Br0.4I0.6)3 perovskite quantum dot film for generation of warm white light,” Chemical Engineering Journal, vol. 313, pp. 461-465, 2017.
[44] J. Zhou, F. Huang, H. Lin, Z. Lin, J. Xu, and Y. Wang, “Inorganic halide perovskite quantum dot modified YAG-based white LEDs with superior performance,” Journal of Materials Chemistry C, vol. 4, no. 32, pp. 7601-7606, 2016.
[45] Q. Chen, H. Zhou, T.-B. Song, S. Luo, Z. Hong, H.-S. Duan, L. Dou, Y. Liu, and Y. Yang, “Controllable self-induced passivation of hybrid lead iodide perovskites toward high performance solar cells,” Nano letters, vol. 14, no. 7, pp. 4158-4163, 2014.
[46] 粘瓈方, “低溫熔點碲玻璃及Li2MgTiO4：Mn4+,Hf4+紅色螢光粉之合成應用於高穩定性之PiG型白光LED,” 國立成功大學電機工程研究所, 2018.
[47] 鄭國清, “近紫外光激發矽酸鹽類螢光粉合成及螢光膠薄層應用於可置換式白光LED,” 國立成功大學電機工程研究所, 2016.
[48] 林欣穎, “無機鈣鈦礦量子點之合成、特性分析與應用,” 國立台灣大學化學研究所, 2016.