عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In present paper, we investigate the effect hole injection layer in the improvement of the performance of organic light-emitting diodes (OLEDs). In particular, the capability of a spin-coated polymer containing polythiophene is compared with the functionality of the Copper(II) phthalocyanine small molecule which is deposited by thermal evaporation. In first step, a reduction from 11.4v to 8.5v is obtained in turn-on voltage of the device by incorporation of calcium as cathode electrode. Next, The effect of adding different hole injection layer diode structure to improve the performance of the device was examined. The functionality of the injection layers are examined by measuring different characteristics, namely current density-voltage, electroluminescence spectra, emission intensity, device lifetime, and current efficiency. Device with Copper(II) phthalocyanine presents superior characteristic comparing to the device which employs polythiophene based conducting polymer; i.e. reduction in turn-on voltage from 8.5v to 6.5v, increase in emission intensity from 1160 cd/m2 to 1600 cd/m2, increase in device lifetime from 72 to 94 hours, and finally enhancement in current efficiency from 0.2 cd/A to 0.6 cd/A.
 G. Gu, V. Bulović, P. E. Burrows, S. R. Forrest, and M. E. Thompson;
"Transparent organic light emitting devices"; Applied Physics Letters 68,
No. 19 (1996) 2606-2608.
 G. Gu, P. E. Burrows, S. Venkatesh, S. R. Forrest, and M. E. Thompson;
"Vacuum-deposited, nonpolymeric flexible organic light-emitting devices";
Optics letters 22, No. 3 (1997) 172-174.
 J. Birnstock, J. Blässing, A. Hunze, M. Scheffel, M. Stößel, K. Heuser,
G. Wittmann, J. Wörle, and A. Winnacker; "Screen-printed passive matrix
displays based on light-emitting polymers"; Applied Physics Letters 78, No.
24 (2001) 3905-3907.
 M. Stewart, R.S. Howell, L. Pires, and M. K. Hatalis; "Polysilicon TFT
technology for active matrix OLED displays"; Electron Devices, IEEE
Transactions on 48, No. 5 (2001) 845-851.
 N. Chopra, J. Lee, Y. Zheng, S.H. Eom, J. Xue, and F. So; "Effect of the
charge balance on high-efficiency blue-phosphorescent organic lightemitting
diodes"; ACS applied materials & interfaces 1, No. 6 (2009) 1169-
 Y. Kawamura, H. Sasabe C. Adachi, "Simple accurate system for
measuring absolute photoluminescence quantum efficiency in organic solidstate
thin films." Japanese journal of applied physics 43, No. 11R (2004)
 K. Saxena, D. S. Mehta, V. K. Rai, , R. Srivastava, , G. Chauhan, M.N.
Kamalasanan, "Implementation of anti-reflection coating to enhance light
out-coupling in organic light-emitting devices."Journal of
Luminescence 128, No. 3 (2008) 525-530.
 N. T. Kalyani, S. J. Dhoble; "Organic light emitting diodes: Energy
saving lighting technology—A review"; Renewable and Sustainable Energy
Reviews 16, No. 5 (2012) 2696-2723.
 A. Islam, M. Rabbani, M. H. Bappy, M. A. R. Miah, N. Sakib; "A review
on fabrication process of organic light emitting diodes"; In Informatics,
Electronics & Vision (ICIEV), 2013 International Conference on, pp. 1-5.
 Y. Chen, H. Tian, Y. Geng, J. Chen, , D. Ma, , D. Yan, L. Wang;
"Organic heterojunctions as a charge generation layer in tandem organic
light-emitting diodes: the effect of interfacial energy level and charge carrier
mobility"; J. Mater. Chem. 21, No. 39 (2011) 15332-15336.
 S. Olthof, R. Meerheim, M. Schober, K. Leo; "Energy level alignment
at the interfaces in a multilayer organic light-emitting diode
structure"; Physical Review B 79, No. 24 (2009) 245308.
 P.Y. Chen, H.Y. Ueng, and M. Yokoyama; "Effects of different buffer
layers on the electro-luminescence performances in white organic lightemitting
diodes"; Journal of Physics and Chemistry of Solids 71, No. 6
 T. C. Li, R. C. Chang, and Y. J. Chen; "Improving the Performance of
Organic Light Emitting Diodes by Doping PEDOT: PSS"; InAdvanced
Materials Research, vol. 881, pp. 1130-1135. 2014.
 R. B. Pode, C. J. Lee, et al. "Transparent conducting metal electrode
for top emission organic light-emitting devices: Ca–Ag double
layer." Applied physics letters 84. No. 23 (2004) 4614-4616.
 W. M. Su, W. L. Li, Q. Zin, et al. "Effect of acceptor on efficiencies of
exciplex-type organic light emitting diodes." Applied Physics Letters 91. No.
4 (2007) 043508.
 Z. EnáOoi, T. LipáTam, et al. "Solution processable bulk-heterojunction
solar cells using a small molecule acceptor." Journal of Materials
Chemistry 18. No. 39 (2008) 4619-4622.
 M. S. White, D. C. Olson, S. E. Shaheen, et al. "Inverted bulkheterojunction
organic photovoltaic device using a solution-derived ZnO
underlayer." Applied Physics Letters 89. No.14 (2006) 143517.