我們使用時間相關單光子計數系統，利用時間解析電致輝光技術量測有機發光二極體從外加偏壓到元件發光所需的延遲時間(delay time)，量測不同外加電壓下延遲時間的變化，進而求得有機材料載子的遷移率，且我們發現使用指數下降函數在擬合所量得曲線，可獲與計數速度(counting rate)無關的延遲時間，並獲得較佳的遷移率估算。
在單層元件中，我們針對不同的發光波長量測元件的延遲時間，發現由缺陷造成的發光比螢光的延遲時間短，此外我們探討不同的製程條件下( 例如溶濟、膜厚、發光面積及蒸鍍不同的陰極等 )，對不同電壓下延遲時間及遷移率的影響，發現(1)就溶濟而言，我們使用二甲笨(xylene)和四氫呋喃(THF)為有機發光層的溶濟，發現溶濟為二甲笨的元件具有較低的延遲時間(2)在相同的膜厚下，面積愈大，造成RC 延遲愈長，故相同外加電壓下的延遲時間愈長，但不影響遷移率。(3)在相同的面積下，厚度愈大，遷移率愈大，且RC延遲愈短，故相同外加電壓下延遲時間愈短(4) 我們分別蒸鍍Ca/Al、CsF/Al 及 LiF/Ca/Al三種不同的陰極，發現陰極為LiF/Ca/Al的具有較高的遷移率。
在雙層元件中，我們亦發現相同的面積下，厚度愈大，載子的遷移率愈大，但對於利用此多層結構在遷移率研究上，尚有許多部分未完善地考慮，仍需進一步研究。

We measure the delay time using the time-resolved electroluminescence (EL) technology by the time-correlated single photon counting system. We calculate the mobility of the organic material based on the delay time at various applied voltages.
We find that by using an exponential function to fit the measured transient fluorescence, delay time independent of the counting rates can be obtained. With delay time extracted in the way, better estimate of the mobility can be obtained.
In single layer structure, we find that the light emitting due to the defects has the shorter delay time than that due to the singlet exciton. Furthermore, we study the delay time and the mobility of the organic material by changing the processing conditions such as the solvent, the emission layer area, the emission layer thickness and the cathode materials. We find that: (1) the use of xylene as solvent of the emission layer leads to shorter delay than THF. (2) the larger the emission area is, the longer the delay time is. This is attributed to the larger area results in the longer RC delay. However the emission area dosen’t affect the carrier mobility. (3) thicker light emission layer shows higher mobility and shorter RC delay; hence leading to the shorter delay time. (4) different cathode materials (Ca/Al, CsF/Al, and LiF/Ca/Al) results in different mobilities, and the devices evaporated on the cathode, LiF/Ca/Al,
shows the highest mobility.
In bilayer structure, we also find that the mobility is thickness dependent. However, some of the difficulties in the mobility study based on the bilayer or
multilayer structure remained unsolved; further investigation is required.

[1] M. Pope, H. P. Kallmann, and P. magnante, Electroluminescence in Organic
Crystals ,.Cehm. Phys. 38, 2042 (1963)
[2] C. W. Tang and SA VanSlyke, Organic electro-luminescent diodes, Appl. Phys. Lett., 51,91,513 (1987)
[3] J. H. Burroughes et al., Visible light emission from semiconductor polymer diodes, Nature 347,539 (1990)
[4] M. J. Winokur, Paula Wamsley, Jeff Moulton, Paul Smith, and A. J. Heeger,
Structural evolution in iodine-doped poly(3-alkylthiophenes),Macromolecules, 13, 3812 (1991)
[5] Kittel, Solid State Physic.
[6] H. Spreitzer, H. Schenk, J. Salbeck, F. Weissoertel, H. Riel, and W. Reiss, Organic Light Emitting Materials and Devices, edited by Z. H. Kafafi, Proc.
[7] U. Wolf, V. I. Arkhipov, and H. Bässler, Current injection from a metal to a disordered hopping system. I. Monte Carlo simulation, Phys. Rev. B 59, 7507 (1999).
[8] D. A. Neamen, Semiconductor Physics & Devices, 2ndED .
[9] S. M. Sze , Physics of Semiconductor Device
[10] E.H. Rhoderick and R.H. Williams, Metal-Semiconductor-Contacts
[11] A. J. Heerger, I, D. Parker, and Y. Yang, Carrier Injection into Semiconducting Polymer: Fowler-Nordheim Field-emission tunneling, Synth. Met. 67,23(1994)
[12] I. D. Parker, Carrier tunneling and device characteristics in polymer light-
emitting diodes, J. Appl. Phys 75 1656 (1994)
[13] M. Wahl, and R. Erdmann, Time-correlated single photon counting in fluorescence lifetime analysis, Photonik 1-2/2000
[14] J. C. Scott, J. H. Kaufman, P. J. Brock, R. DiPietro, J. Salem, and J. A. Goitia, Degradation and failure of MEH-PPV light-emitting diodes, J. Appl. Phys., 79, 2745(1996)
[15] A. R. Schlatmann, D. Wilms Floet, A. Hilberer, F. Garten, P. J. M. Smulders, T. M. Klapwijk, and G. Hadziioannou, Indium contamination from the indium–
tin–oxide electrode in polymer light-emitting diodes, Appl. Phys. Lett., 69, 1764(1996)
[16] 陳重餘碩士論文
[17] M. Ichikawa, Y. Horiba, H. Nakatani, M. Yamada, T. Koyama, Y, and Taniguchi,
Method of Measuring Charge Carrier Mobility in Organic Light-Emitting
Diodes Using Fast Transient Electroluminescence Responses, Jpn. J. Appl.
Phys., 41, 2252 (2002)
[18] C. Hosokawa, H. Tokailin, H. Higashi and T. Kusumoto, Transient behavior of organic thin film electroluminescence, Appl. Phys. Lett., 60, 1220 (1992)
[19] Y. Ohmori, C. Morishita, M. Uchida, and K. Yoshino, Time-Resolved Pulse Response of Electroluminescence in Poly(3-alkylthiophene) Diodes, Jpn. J. Appl. Phys. 31, L568 (1992)
[20] A. G. Muckl, S. Berleb, W. Brutting, and M. Schwoerer, Transient electro-
luminescence measurements on organic heterolayer light emitting diodes, Synth. Met., 111-112, 91, (2000)
[21] S. C. Tse, H. H. Fong, and S. K. So, Electron transit time and reliable mobility measurements from thick film hydroxyquinoline-based organic light-emitting diode, J . Appl. Phys. 94, 2033 (2003)
[22] S. E. Shaheen, G. E. Jabbour, M. M. Morrell, Y. Kawabe, B. Kippelen, and N. Peyghambarian, Bright blue organic light-emitting diode with improved color purity using a LiF/Al cathode, J. Appl. Phys., 84, 2324 (1998)
[23] H. Chen, M. Wong, H.S. Kwok, Dopant emission mechanism and the effects of host materials on the behavior of doped organic light-emitting diodes, IEEE, 49, 1540 (2002)