近年來有機發光二極體已經被廣泛應用於小型顯示器上，但有許多研究者仍致力於提升元件的效率與穩定性，其中一項為改善發光層內的載子平衡與發光效率，因此元件發展至今其發光層多半為多摻雜系統，然而目前對於多摻雜型系統內的載子傳輸特性卻鮮少被研究。
本論文藉由飛行時間法(Time of Flight, TOF)來探討多重摻雜型發光層內的載子傳輸行為。首先，我們探討PH001及PH002本身的載子傳輸特性，接著再將PH001與PH002以75%:25%的重量百分濃度做為雙主體結構，最後再摻入6%、12%、18%的客體24FTIr(acac)到雙主體內，藉此探討發光層傳輸特性，在我們的摻雜的系統中，PH001為多數分子，因此PH002及24FTIr(acac)會形成PH001的載子陷阱或散射中心，所以我們會以PH001的能階作為基準來探討多摻雜系統內的載子傳輸特性。除此之外，為了更深入的探討載子傳輸的特性，我們會對元件進行變溫及變電壓實驗來得到高斯亂度模型(Gaussian disorder model)的模型參數並做進一步的分析與討論。
本研究顯示當摻雜物為深載子陷阱或高散射中心時，會使載子遷移率相較於未摻雜前稍微下降且能量亂度稍微提升(1~6 meV)；若摻雜物為淺載子陷阱或低散射中心時，會使載子遷移率相較於未摻雜前大幅下降且能量亂度大幅提升 (~29 meV)。

Organic light-emitting diodes (OLEDs) have been widely applied to the small-sized displays for the past few years. However, there are lots of researchers dedicating themselves to improving the efficiency and stability of OLED devices. The significant solutions to improve the device performance are balancing charge carriers in the emission layer and enhancing the photoluminescent quantum yields of the emission layer. As a result, the mixed emission layer has been generally used in most OLED devices. However, the studies of charge transport behaviors in the mixed system are still lacking.
In this thesis, we use the time-of-flight method to investigate the charge transport behaviors in a multi-doped emission layer. At first, we examined the transport properties of the pristine PH001 and PH002. Afterward, we studied the charge transport mechanisms of the PH001: PH002=75%:25% co-host system and the multi-doped emission layers with the same co-host system under different mass fraction of 24FTIr(acac) (6%, 12% and 18%). In our system, the majority of molecules are PH001 which means the PH002 and 24FTIr(acac) act as the charge traps and scatters against the PH001. Therefore, the charge transport behaviors we discussed in our multi-doped system are based on the energy level of the PH001. In order to further understand the detailed charge transport mechanism, we also investigated the temperature and field dependence of our multi-doped system in order to discuss and analyze them with Gaussian disorder model.
Our study reports that if dopants act as deep traps (or high scatters), the mobility and energetic disorder slightly reduce and increase (1~6 meV) respectively, whereas the shallow traps (or low scatters) greatly decrease the mobility and increase the energetic disorder substantially (~29 meV).

中文審定書 i
英文審定書 ii
致謝 iii
摘要 iv
Abstract v
目錄 vii
圖目錄 viii
表目錄 xi
第一章 緒論 1
1-1前言 1
1-2有機半導體載子傳遞機制 2
1-3載子傳遞特性對有機發光二極體之影響 8
1-4研究動機 11
第二章 實驗方法 12
2-1前言 12
2-2飛行時間量測法(time-of-flight measurement) 12
2-2-1原理與機制 12
2-2-2光電流訊號分析 14
2-2-4 實驗元件製程 16
2-3實驗設備介紹 19
第三章 實驗結果與討論 21
3-1前言 21
3-2-1材料PH001 22
3-2-2材料PH002 23
3-2-3雙主體結構PH001:PH002=75%:25% 24
3-2-4發光層結構PH001:PH002:24FTIr(acac)=75%:25%:6% 25
3-2-5發光層結構PH001:PH002:24FTIr(acac)=75%:25%:12% 26
3-2-6發光層結構PH001:PH002:24FTIr(acac)=75%:25%:18% 27
3-3 結果與討論 52
3-3-1光電流訊號分析 52
3-3-2載子遷移率分析 53
3-3-2高斯亂度模型分析 54
第四章 結論與未來工作 58
參考資料 59

[1] V. Avrutin, N. Izyumskaya, and H. Morkoc, "Semiconductor solar cells: recent progress in terrestrial applications," Superlattices and Microstructures, vol. 49, no. 4, pp. 337-364, 2011.
[2] K. Nomura, H. Ohta, K. Ueda, T. Kamiya, M. Hirano, and H. Hosono, "Thin-film transistor fabricated in single-crystalline transparent oxide semiconductor," Science, vol. 300, no. 5623, pp. 1269-1272, 2003.
[3] M. Kuznetsov, F. Hakimi, R. Sprague, and A. Mooradian, "High-power (> 0.5-W CW) diode-pumped vertical-external-cavity surface-emitting semiconductor lasers with circular TEM/sub 00/beams," IEEE Photonics Technology Letters, vol. 9, no. 8, pp. 1063-1065, 1997.
[4] D. H. Kim, J. H. Ahn, W. M. Choi, H. S. Kim, T. H. Kim, J. Song, Y. Y. Huang, Z. Liu, C. Lu, and J. A. Rogers, "Stretchable and foldable silicon integrated circuits," Science, vol. 320, no. 5875, pp. 507-511, 2008.
[5] I. Schnitzer, E. Yablonovitch, C. Caneau, T. J. Gmitter, and A. Scherer, "30% external quantum efficiency from surface textured, thin-film light-emitting-diodes," Applied Physics Letters, vol. 63, no. 16, pp. 2174-2176, 1993.
[6] S. E. Shaheen, C. J. Brabec, N. S. Sariciftci, F. Padinger, T. Fromherz, and J. C. Hummelen, "2.5% efficient organic plastic solar cells," Applied Physics Letters, vol. 78, no. 6, pp. 841-843, 2001.
[7] S. F. Tedde, J. Kern, T. Sterzl, J. Furst, P. Lugli, and O. Hayden, "Fully spray coated organic photodiodes," Nano Letters, vol. 9, no. 3, pp. 980-983, 2009.
[8] Y. Diao, B. C. K. Tee, G. Giri, J. Xu, D. H. Kim, H. A. Becerril, R. M. Stoltenberg, T. H. Lee, G. Xue, S. C. B. Mannsfeld, and Z. Bao, "Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains," Nature Materials, vol. 12, no. 7, pp. 665-671, 2013.
[9] S. R. Forrest, "The path to ubiquitous and low-cost organic electronic appliances on plastic," Nature, vol. 428, no. 6986, pp. 911-918, 2004.
[10] S. E. Shaheen, D. S. Ginley, and G. E. Jabbour, "Organic-based photovoltaics. toward low-cost power generation," MRS Bulletin, vol. 30, no. 1, pp. 10-19, 2005.
[11] M. Ramuz, B. C. K. Tee, J. B. H. Tok, and Z. N. Bao, "Transparent, optical, pressure-sensitive artificial skin for large-area stretchable electronics," Advanced Materials, vol. 24, no. 24, pp. 3223-3227, 2012.
[12] L. A. Duan, J. A. Qiao, Y. D. Sun, and Y. Qiu, "Strategies to design bipolar small molecules for oleds: donor-acceptor structure and non-donor-acceptor structure," Advanced Materials, vol. 23, no. 9, pp. 1137-1144, 2011.
[13] M. t. Dewar and H. Schmeising, "Resonance and conjugation—II factors determining bond lengths and heats of formation," Tetrahedron, vol. 11, no. 1-2, pp. 96-120, 1960.
[14] V. Hernandez, C. Castiglioni, M. Del Zoppo, and G. Zerbi, "Confinement potential and π-electron delocalization in polyconjugated organic materials," Physical Review B, vol. 50, no. 14, p. 9815, 1994.
[15] G. Pfister, "Hopping transport in a molecularly doped organic polymer," Physical Review B, vol. 16, no. 8, p. 3676, 1977.
[16] J. G. Simmons, "Poole-Frenkel effect and Schottky effect in metal-insulator-metal systems," Physical Review, vol. 155, no. 3, p. 657, 1967.
[17] H. Bässler, "Charge transport in disordered organic photoconductors a Monte Carlo simulation study," Physica Status Solidi (b), vol. 175, no. 1, pp. 15-56, 1993.
[18] C. Deibel and V. Dyakonov, "Polymer–fullerene bulk heterojunction solar cells," Reports on Progress in Physics, vol. 73, no. 9, p. 096401, 2010.
[19] D. Monroe, "Hopping in exponential band tails," Physical Review Letters, vol. 54, no. 2, p. 146, 1985.
[20] G. Gu, D. Garbuzov, P. Burrows, S. Venkatesh, S. Forrest, and M. Thompson, "High-external-quantum-efficiency organic light-emitting devices," Optics Letters, vol. 22, no. 6, pp. 396-398, 1997.
[21] C. Adachi, M. A. Baldo, S. R. Forrest, and M. E. Thompson, "High-efficiency organic electrophosphorescent devices with tris (2-phenylpyridine) iridium doped into electron-transporting materials," Applied Physics Letters, vol. 77, no. 6, pp. 904-906, 2000.
[22] Y. Hamada, H. Kanno, T. Tsujioka, H. Takahashi, and T. Usuki, "Red organic light-emitting diodes using an emitting assist dopant," Applied Physics Letters, vol. 75, no. 12, pp. 1682-1684, 1999.
[23] N. Von Malm, J. Steiger, R. Schmechel, and H. Von Seggern, "Trap engineering in organic hole transport materials," Journal of Applied Physics, vol. 89, no. 10, pp. 5559-5563, 2001.
[24] K. Tsung and S. So, "Carrier trapping and scattering in amorphous organic hole transporter," Applied Physics Letters, vol. 92, no. 10, p. 95, 2008.
[25] C. Li, L. Duan, H. Li, and Y. Qiu, "Universal trap effect in carrier transport of disordered organic semiconductors: transition from shallow trapping to deep trapping," The Journal of Physical Chemistry C, vol. 118, no. 20, pp. 10651-10660, 2014.
[26] C. Li, L. Duan, Y. Sun, H. Li, and Y. Qiu, "Charge transport in mixed organic disorder semiconductors: trapping, scattering, and effective energetic disorder," The Journal of Physical Chemistry C, vol. 116, no. 37, pp. 19748-19754, 2012.
[27] F. Laquai, G. Wegner, and H. Bässler, "What determines the mobility of charge carriers in conjugated polymers?" Physical and Engineering Sciences, vol. 365, no. 1855, pp. 1473-1487, 2007.
[28] T. H. Liu, C. Y. Iou, and C. H. Chen, "Doped red organic electroluminescent devices based on a cohost emitter system," Applied Physics Letters, vol. 83, no. 25, pp. 5241-5243, 2003.
[29] S. Lee, K. H. Kim, D. Limbach, Y. S. Park, and J. J. Kim, "Low roll‐off and high efficiency orange organic light emitting diodes with controlled co‐doping of green and red phosphorescent dopants in an exciplex forming co‐host," Advanced Functional Materials, vol. 23, no. 33, pp. 4105-4110, 2013.