本篇論文提出了一種高亮度與高色光純度之紅光量子點發光二極體，其元件結構由有機與無機載子傳輸層將發光層夾在中間，並經由溶液製程法完成製作。
本研究之第一項調整為使用氧化鋅奈米粒子取代以有機材料為電子傳輸層之量子點發光二極體。以氧化鋅奈米粒子作為電子傳輸層不只提升了元件效能，也可延長其半衰期。使用氧化鋅奈米粒子為電子傳輸層元件僅需2.5伏特的電壓便可啟動，同時具有最大亮度66,727 cd/m2，以及最大電流效率5.6 cd/A。此外，元件在未封裝情況下也具備了至少20個小時的半衰期。
除了改善電子傳輸層，電洞傳輸層也需要強化。使用poly-TPD與PVK的混合聚合物作為電動傳輸層是本實驗的第二個嘗試。混合材料可將poly-TPD的高電動遷移率與PVK較適合電動傳輸的能帶分布予以結合，進而改善載子平衡。在這個階段，最大亮度與最大電流效率分別提高至177,675 cd/m2以及14.0 cd/A。
混合聚合物在加入小分子材料TCTA作為參雜，可更進一步提升電洞傳輸。在第三階段的實驗中，這項改善將亮度與電流效率提升到本論文最高值，達到了254,041 cd/m2以及14.6 cd/A。

High brightness and high color purity red-emissive colloidal quantum dot light-emitting diodes are demonstrated in this thesis. The device architecture is composed with solution-processed organic/ inorganic charge transporting layers (CTL) and a sandwiched giant quantum dot emissive layer.
The initial change is substituting Zinc oxide nanoparticles (ZnO NPs) for organic electron transporting layer (ETL). ZnO NPs not only enhanced device performance but also extended lifetime. Based on ZnO NPs, these devices provided lower turn-on voltage at 2.5 V, higher luminance of 66,727 cd/m2 and increased current efficiency of 5.6 cd/A. In addition, it also indicated longer lifetime at least 20 hours without package.
Hole transporting layer (HTL) improvement is the following issue. Hybrid polymer HTL blended with poly(4-butylphenyl-diphenyl-amine) (poly-TPD) and Poly(9-vinylcarbazole) (PVK) is introduced for offsetting mobility difference and between organic HTL and ZnO NPs ETL and achieved suitable energy band alignment, resulting in better charge balance . This modification enhanced luminance and current efficiency to 177,675 cd/m2 and 14.0 cd/A.
Small molecule material TCTA was doped into the hybrid polymer HTL for further rising hole mobility. This method performed best luminance and current efficiency with the peak values of 254,041 cd/m2 and 14.6 cd/A.

[1] P. Kathirgamanathan, L. M. Bushby, M. Kumaraverl, S. Ravichandran, and S. Surendrakumar, "Electroluminescent Organic and Quantum Dot LEDs: The State of the Art," (in English), Journal of Display Technology, vol. 11, no. 5, pp. 480-493, May 2015.
[2] N. Holonyak and S. F. Bevacqua, "COHERENT (VISIBLE) LIGHT EMISSION FROM Ga(As1−xPx) JUNCTIONS," Applied Physics Letters, vol. 1, no. 4, pp. 82-83, 1962.
[3] S. Nakamura, T. Mukai, and M. Senoh, "Candela‐class high‐brightness InGaN/AlGaN double‐heterostructure blue‐light‐emitting diodes," Applied Physics Letters, vol. 64, no. 13, pp. 1687-1689, 1994.
[4] A. Bernanose, "Electroluminescence of organic compounds," British Journal of Applied Physics, vol. 6, no. S4, pp. S54-S55, 1955.
[5] H. Kallmann and M. Pope, "Bulk Conductivity in Organic Crystals," Nature, vol. 186, no. 4718, pp. 31-33, 1960.
[6] H. Kallmann and M. Pope, "Positive Hole Injection into Organic Crystals," (in English), Journal of Chemical Physics, vol. 32, no. 1, pp. 300-301, 1960.
[7] W. Helfrich and Schneide.Wg, "Recombination Radiation in Anthracene Crystals," (in English), Physical Review Letters, vol. 14, no. 7, pp. 229-&, 1965.
[8] C. W. Tang and S. A. Vanslyke, "Organic Electroluminescent Diodes," (in English), Applied Physics Letters, vol. 51, no. 12, pp. 913-915, Sep 21 1987.
[9] J. H. Burroughes et al., "Light-emitting diodes based on conjugated polymers," Nature, vol. 347, no. 6293, pp. 539-541, 1990.
[10] S. A. Van Slyke, C. H. Chen, and C. W. Tang, "Organic electroluminescent devices with improved stability," Applied Physics Letters, vol. 69, no. 15, pp. 2160-2162, 1996.
[11] A. I. Ekimov, A. L. Efros, and A. A. Onushchenko, "Quantum size effect in semiconductor microcrystals," Solid State Communications, vol. 56, no. 11, pp. 921-924, 1985.
[12] Y. H. Niu et al., "Improved Performance from Multilayer Quantum Dot Light-Emitting Diodes via Thermal Annealing of the Quantum Dot Layer," Advanced Materials, vol. 19, no. 20, pp. 3371-3376, 2007.
[13] P. O. Anikeeva, J. E. Halpert, M. G. Bawendi, and V. Bulovic, "Quantum Dot Light-Emitting Devices with Electroluminescence Tunable Over the Entire Visible Spectrum," Nano Lett, vol. 9, no. 7, pp. 2532-6, Jul 2009.
[14] V. L. Colvin, M. C. Schlamp, and A. P. Alivisatos, "Light-emitting diodes made from cadmium selenide nanocrystals and a semiconducting polymer," Nature, vol. 370, no. 6488, pp. 354-357, 1994.
[15] Y. Shirasaki, G. J. Supran, M. G. Bawendi, and V. Bulovic, "Emergence of Colloidal Quantum-Dot Light-Emitting Technologies," (in English), Nature Photonics, vol. 7, no. 1, pp. 13-23, Jan 2013.
[16] B. O. Dabbousi, M. G. Bawendi, O. Onitsuka, and M. F. Rubner, "Electroluminescence from CdSe quantum‐dot/polymer composites," Applied Physics Letters, vol. 66, no. 11, pp. 1316-1318, 1995.
[17] H. Mattoussi, L. H. Radzilowski, B. O. Dabbousi, E. L. Thomas, M. G. Bawendi, and M. F. Rubner, "Electroluminescence from heterostructures of poly(phenylene vinylene) and inorganic CdSe nanocrystals," (in English), Journal of Applied Physics, vol. 83, no. 12, pp. 7965-7974, Jun 15 1998.
[18] S. Coe, W. K. Woo, M. Bawendi, and V. Bulovic, "Electroluminescence from single monolayers of nanocrystals in molecular organic devices," Nature, 10.1038/nature01217 vol. 420, no. 6917, pp. 800-3, Dec 19-26 2002.
[19] A. H. Mueller et al., "Multicolor light-emitting diodes based on semiconductor nanocrystals encapsulated in GaN charge injection layers," Nano Lett, vol. 5, no. 6, pp. 1039-44, Jun 2005.
[20] V. Wood, M. J. Panzer, J. E. Halpert, J. M. Caruge, M. G. Bawendi, and V. Bulovic, "Selection of metal oxide charge transport layers for colloidal quantum dot LEDs," ACS Nano, vol. 3, no. 11, pp. 3581-6, Nov 24 2009.
[21] K. H. Lee et al., "Over 40 cd/A efficient green quantum dot electroluminescent device comprising uniquely large-sized quantum dots," ACS Nano, vol. 8, no. 5, pp. 4893-901, May 27 2014.
[22] J. R. Manders et al., "High efficiency and ultra-wide color gamut quantum dot LEDs for next generation displays," (in English), Journal of the Society for Information Display, vol. 23, no. 11, pp. 523-528, Nov 2015.
[23] V. Wood and V. Bulovic, "Colloidal Quantum Dot Light-Emitting Devices," Nano Rev, vol. 1, 2010.
[24] H. T. Vu et al., "Cesium Azide-An Efficient Material for Green Light-Emitting Diodes With Giant Quantum Dots," (in English), IEEE Photonics Technology Letters, vol. 27, no. 20, pp. 2123-2126, Oct 15 2015.
[25] G. F. Wang, X. M. Tao, and R. X. Wang, "Fabrication and characterization of OLEDs using PEDOT:PSS and MWCNT nanocomposites," (in English), Composites Science and Technology, vol. 68, no. 14, pp. 2837-2841, Nov 2008.
[26] S. Shui-Hsiang, C. Wang-Ta, H. Cheng-Chieh, K. Lien-Cheng, and Y. Meiso, "Enhancing Efficiency of Organic Light-Emitting Diodes Using a Carbon-Nanotube-Doped Hole Injection Layer," Japanese Journal of Applied Physics, vol. 49, no. 4S, p. 04DK12, 2010.
[27] B. R. Lee et al., "Highly efficient polymer light-emitting diodes using graphene oxide as a hole transport layer," ACS Nano, vol. 6, no. 4, pp. 2984-91, Apr 24 2012.
[28] S. W. Shi, V. Sadhu, R. Moubah, G. Schmerber, Q. Y. Bao, and S. R. P. Silva, "Solution-processable graphene oxide as an efficient hole injection layer for high luminance organic light-emitting diodes," (in English), Journal of Materials Chemistry C, vol. 1, no. 9, pp. 1708-1712, 2013.
[29] X. Yang et al., "Solution processed tungsten oxide interfacial layer for efficient hole-injection in quantum dot light-emitting diodes," Small, vol. 10, no. 2, pp. 247-52, Jan 29 2014.
[30] P. Jing et al., "Vacuum-Free Transparent Quantum Dot Light-Emitting Diodes with Silver Nanowire Cathode," Sci Rep, vol. 5, p. 12499, 2015.
[31] H. Kim et al., "Electrical, optical, and structural properties of indium–tin–oxide thin films for organic light-emitting devices," Journal of Applied Physics, vol. 86, no. 11, pp. 6451-6461, 1999.
[32] N. Straue, M. Rauscher, M. Dressler, and A. Roosen, "Tape Casting of ITO Green Tapes for Flexible Electroluminescent Lamps," (in English), Journal of the American Ceramic Society, vol. 95, no. 2, pp. 684-689, Feb 2012.
[33] J. Du et al., "Highly transparent and conductive indium tin oxide thin films for solar cells grown by reactive thermal evaporation at low temperature," (in English), Applied Physics a-Materials Science & Processing, vol. 117, no. 2, pp. 815-822, Nov 2014.
[34] S. J. Lee, B. S. Kim, J. Y. Kim, A. B. Yusoff, and J. Jang, "Stable organic photovoltaic with PEDOT:PSS and MoOX mixture anode interfacial layer without encapsulation," (in English), Organic Electronics, vol. 19, pp. 140-146, Apr 2015.
[35] E. Bovill et al., "The role of the hole-extraction layer in determining the operational stability of a polycarbazole: fullerene bulk-heterojunction photovoltaic device," (in English), Applied Physics Letters, vol. 106, no. 7, Feb 16 2015, Art. no. 073301.
[36] Y. Park et al., "Flexible, light trapping substrates for organic photovoltaics," Applied Physics Letters, vol. 109, no. 9, p. 093301, 2016.
[37] Y. Park, F. Nehm, L. Muller-Meskamp, K. Vandewal, and K. Leo, "Optical display film as flexible and light trapping substrate for organic photovoltaics," Opt Express, vol. 24, no. 10, pp. A974-80, May 16 2016.
[38] Y. H. Kim, C. Sachse, M. L. Machala, C. May, L. Muller-Meskamp, and K. Leo, "Highly Conductive PEDOT:PSS Electrode with Optimized Solvent and Thermal Post-Treatment for ITO-Free Organic Solar Cells," (in English), Advanced Functional Materials, vol. 21, no. 6, pp. 1076-1081, Mar 22 2011.
[39] J. Saghaei, A. Fallahzadeh, and T. Saghaei, "ITO-free organic solar cells using highly conductive phenol-treated PEDOT:PSS anodes," (in English), Organic Electronics, vol. 24, pp. 188-194, Sep 2015.
[40] W. C. Lai, K. W. Lin, T. F. Guo, and J. Lee, "Perovskite-Based Solar Cells With Nickel-Oxidized Nickel Oxide Hole Transfer Layer," (in English), IEEE Transactions on Electron Devices, vol. 62, no. 5, pp. 1590-1595, May 2015.
[41] A. Garg, S. K. Gupta, J. J. Jasieniak, T. B. Singh, and S. E. Watkins, "Improved lifetimes of organic solar cells with solution-processed molybdenum oxide anode-modifying layers," (in English), Progress in Photovoltaics, vol. 23, no. 8, pp. 989-996, Aug 2015.
[42] A. Benor, S.-y. Takizawa, C. Pérez-Bolívar, and P. Anzenbacher, "Efficiency Improvement of Fluorescent Oleds by Tuning the Working Function of Pedot:Pss Using Uv–Ozone Exposure," Organic Electronics, vol. 11, no. 5, pp. 938-945, 2010.
[43] W. Brutting, J. Frischeisen, T. D. Schmidt, B. J. Scholz, and C. Mayr, "Device efficiency of organic light-emitting diodes: Progress by improved light outcoupling," (in English), Physica Status Solidi a-Applications and Materials Science, vol. 210, no. 1, pp. 44-65, Jan 2013.
[44] Y. H. Kim, J. Lee, S. Hofmann, M. C. Gather, L. Muller-Meskamp, and K. Leo, "Achieving High Efficiency and Improved Stability in ITO-Free Transparent Organic Light-Emitting Diodes with Conductive Polymer Electrodes," (in English), Advanced Functional Materials, vol. 23, no. 30, pp. 3763-3769, Aug 12 2013.
[45] Y. L. Kong et al., "3D Printed Quantum Dot Light-Emitting Diodes," Nano Lett, vol. 14, no. 12, pp. 7017-23, Dec 10 2014.
[46] Q. L. Lin et al., "Cadmium-free quantum dots based violet light-emitting diodes: High-efficiency and brightness via optimization of organic hole transport layers," (in English), Organic Electronics, vol. 25, pp. 178-183, Oct 2015.
[47] J. Pan et al., "Flexible Quantum Dot Light Emitting Diodes Based On ZnO Nanoparticles," RSC Adv., vol. 5, no. 100, pp. 82192-82198, 2015.
[48] M. Vosgueritchian, D. J. Lipomi, and Z. A. Bao, "Highly Conductive and Transparent PEDOT:PSS Films with a Fluorosurfactant for Stretchable and Flexible Transparent Electrodes," (in English), Advanced Functional Materials, vol. 22, no. 2, pp. 421-428, Jan 25 2012.
[49] B. J. Worfolk et al., "Ultrahigh electrical conductivity in solution-sheared polymeric transparent films," Proc Natl Acad Sci U S A, vol. 112, no. 46, pp. 14138-43, Nov 17 2015.
[50] J. Kwak et al., "Bright and Efficient Full-Color Colloidal Quantum Dot Light-Emitting Diodes Using an Inverted Device Structure," (in English), Nano Lett, vol. 12, no. 5, pp. 2362-6, May 9 2012.
[51] W. K. Bae et al., "R/G/B/natural white light thin colloidal quantum dot-based light-emitting devices," Adv Mater, vol. 26, no. 37, pp. 6387-93, Oct 8 2014.
[52] C.-Y. Huang and J.-H. Lai, "Efficient polymer light-emitting diodes with ZnO nanoparticles and interpretation of observed sub-bandgap turn-on phenomenon," Organic Electronics, vol. 32, pp. 244-249, 2016.
[53] Q. Sun et al., "Bright, multicoloured light-emitting diodes based on quantum dots," (in English), Nature Photonics, vol. 1, no. 12, pp. 717-722, Dec 2007.
[54] P. O. Anikeeva, C. F. Madigan, J. E. Halpert, M. G. Bawendi, and V. Bulovic, "Electronic and excitonic processes in light-emitting devices based on organic materials and colloidal quantum dots," (in English), Physical Review B, vol. 78, no. 8, Aug 2008.
[55] W. K. Bae et al., "Multicolored Light-Emitting Diodes Based On All-Quantum-Dot Multilayer Films Using Layer-by-Layer Assembly Method," Nano Lett, vol. 10, no. 7, pp. 2368-73, Jul 14 2010.
[56] D. P. Puzzo, E. J. Henderson, M. G. Helander, Z. Wang, G. A. Ozin, and Z. Lu, "Visible Colloidal Nanocrystal Silicon Light-Emitting Diode," Nano Lett, vol. 11, no. 4, pp. 1585-90, Apr 13 2011.
[57] B. H. Kang et al., "Highly Efficient White Light-Emitting Diodes Based on Quantum Dots and Polymer Interface," (in English), IEEE Photonics Technology Letters, vol. 24, no. 18, pp. 1594-1596, Sep 15 2012.
[58] K. S. Leck et al., "Quantum dot light-emitting diode with quantum dots inside the hole transporting layers," ACS Appl Mater Interfaces, vol. 5, no. 14, pp. 6535-40, Jul 24 2013.
[59] S. H. Song et al., "Highly Efficient Light-Emitting Diode of Graphene Quantum Dots Fabricated from Graphite Intercalation Compounds," (in English), Advanced Optical Materials, vol. 2, no. 11, pp. 1016-1023, Nov 2014.
[60] H. Cho et al., "Soft Contact Transplanted Nanocrystal Quantum Dots for Light-Emitting Diodes: Effect of Surface Energy On Device Performance," ACS Appl Mater Interfaces, vol. 7, no. 20, pp. 10828-33, May 27 2015.
[61] X. Chen, R. Yan, W. Zhang, and J. Fan, "Carrier recombination spatial transfer by reduced potential barrier causes blue/red switchable luminescence in C8 carbon quantum dots/organic hybrid light-emitting devices," APL Materials, vol. 4, no. 4, p. 046102, 2016.
[62] J. W. Stouwdam and R. A. J. Janssen, "Red, green, and blue quantum dot LEDs with solution processable ZnO nanocrystal electron injection layers," (in English), Journal of Materials Chemistry, vol. 18, no. 16, pp. 1889-1894, 2008.
[63] K. S. Cho et al., "High-Performance Crosslinked Colloidal Quantum-Dot Light-Emitting Diodes," (in English), Nature Photonics, vol. 3, no. 6, pp. 341-345, Jun 2009.
[64] L. Qian, Y. Zheng, J. G. Xue, and P. H. Holloway, "Stable and Efficient Quantum-Dot Light-Emitting Diodes Based On Solution-Processed Multilayer Structures," (in English), Nature Photonics, vol. 5, no. 9, pp. 543-548, Sep 2011.
[65] C.-J. Chen, C.-Y. Huang, J.-Y. Lien, S.-L. Wang, and R.-K. Chiang, "High-Performance Electroluminescence Devices Based on Size-Uniform Gigantic Red-Emission Quantum Dots," SID Symposium Digest of Technical Papers, vol. 47, no. 1, pp. 1487-1490, 2016.
[66] W. Y. Hung et al., "Employing ambipolar oligofluorene as the charge-generation layer in time-of-flight mobility measurements of organic thin films," (in English), Applied Physics Letters, vol. 88, no. 6, p. 064102, Feb 6 2006.
[67] X. Dai et al., "Solution-Processed, High-Performance Light-Emitting Diodes Based On Quantum Dots," Nature, vol. 515, no. 7525, pp. 96-9, Nov 6 2014.
[68] Y. X. Yang et al., "High-efficiency light-emitting devices based on quantum dots with tailored nanostructures," (in English), Nature Photonics, vol. 9, no. 4, pp. 259-266, Apr 2015.
[69] F. Zhao et al., "Highly flexible organometal halide perovskite quantum dot based light-emitting diodes on a silver nanowire–polymer composite electrode," J. Mater. Chem. C, vol. 5, no. 3, pp. 531-538, 2017.
[70] S. Nam, N. Oh, Y. Zhai, and M. Shim, "High efficiency and optical anisotropy in double-heterojunction nanorod light-emitting diodes," ACS Nano, vol. 9, no. 1, pp. 878-85, Jan 27 2015.
[71] J. Zhao et al., "Efficient CdSe/CdS quantum dot light-emitting diodes using a thermally polymerized hole transport layer," Nano Lett, vol. 6, no. 3, pp. 463-7, Mar 2006.
[72] Q. Sun et al., "Highly efficient quantum-dot light-emitting diodes with DNA-CTMA as a combined hole-transporting and electron-blocking layer," ACS Nano, vol. 3, no. 3, pp. 737-43, Mar 24 2009.
[73] D. I. Son, H. H. Kim, D. K. Hwang, S. Kwon, and W. K. Choi, "Inverted CdSe–ZnS quantum dots light-emitting diode using low-work function organic material polyethylenimine ethoxylated," J. Mater. Chem. C, vol. 2, no. 3, pp. 510-514, 2014.
[74] H. H. Kim et al., "Inverted quantum dot light emitting diodes using polyethylenimine ethoxylated modified ZnO," Sci Rep, vol. 5, p. 8968, Mar 10 2015.
[75] H. H. Kim et al., "Highly flexible inverted-quantum-dot light-emitting diodes on elastic polyurethane substrates," (in English), Journal of Materials Chemistry C, vol. 5, no. 7, pp. 1596-1600, 2017.
[76] M. W. Thesen et al., "Hole-Transporting Host-Polymer Series Consisting of Triphenylamine Basic Structures for Phosphorescent Polymer Light-Emitting Diodes," (in English), Journal of Polymer Science Part a-Polymer Chemistry, vol. 48, no. 15, pp. 3417-3430, Aug 1 2010.
[77] D. H. Lee, Y. P. Liu, K. H. Lee, H. Chae, and S. M. Cho, "Effect of hole transporting materials in phosphorescent white polymer light-emitting diodes," (in English), Organic Electronics, vol. 11, no. 3, pp. 427-433, Mar 2010.
[78] D. D. Zhang et al., "Realizing both improved luminance and stability in organic light-emitting devices based on a solution-processed inter-layer composed of MoOX and Au nanoparticles mixture," (in English), Organic Electronics, vol. 15, no. 4, pp. 961-967, Apr 2014.
[79] F. Chen et al., "Enhanced Performance of Quantum Dot-Based Light-Emitting Diodes with Gold Nanoparticle-Doped Hole Injection Layer," Nanoscale Res Lett, vol. 11, no. 1, p. 376, Dec 2016.
[80] M. D. Ho, D. Kim, N. Kim, S. M. Cho, and H. Chae, "Polymer and small molecule mixture for organic hole transport layers in quantum dot light-emitting diodes," ACS Appl Mater Interfaces, vol. 5, no. 23, pp. 12369-74, Dec 11 2013.
[81] B. S. Mashford et al., "High-Efficiency Quantum-Dot Light-Emitting Devices with Enhanced Charge Injection," (in English), Nature Photonics, vol. 7, no. 5, pp. 407-412, May 2013.
[82] Y. G. Ha, E. A. You, B. J. Kim, and J. H. Choi, "Fabrication and characterization of OLEDs using MEH-PPV and SWCNT nanocomposites," (in English), Synthetic Metals, vol. 153, no. 1-3, pp. 205-208, Sep 21 2005.
[83] Z. Zhong, Y. F. Dai, D. G. Ma, and Z. Y. Wang, "Facile synthesis of organo-soluble surface-grafted all-single-layer graphene oxide as hole-injecting buffer material in organic light-emitting diodes," (in English), Journal of Materials Chemistry, vol. 21, no. 16, pp. 6040-6045, 2011.
[84] S. Y. Liu, R. Liu, Y. Chen, S. H. Ho, J. H. Kim, and F. So, "Nickel Oxide Hole Injection/Transport Layers for Efficient Solution-Processed Organic Light-Emitting Diodes," (in English), Chemistry of Materials, vol. 26, no. 15, pp. 4528-4534, Aug 12 2014.
[85] Y. D. Zhang, S. J. Wang, L. Chen, Y. Fang, H. B. Shen, and Z. L. Du, "Solution-processed quantum dot light-emitting diodes based on NiO nanocrystals hole injection layer," (in English), Organic Electronics, vol. 44, pp. 189-197, May 2017.
[86] H. T. Nguyen, N. D. Nguyen, and S. Lee, "Application of solution-processed metal oxide layers as charge transport layers for CdSe/ZnS quantum-dot LEDs," Nanotechnology, vol. 24, no. 11, p. 115201, Mar 22 2013.
[87] H. T. Nguyen, H. Jeong, J. Y. Park, Y. H. Ahn, and S. Lee, "Charge transport in light emitting devices based on colloidal quantum dots and a solution-processed nickel oxide layer," ACS Appl Mater Interfaces, vol. 6, no. 10, pp. 7286-91, May 28 2014.