WU Jun, ZHONG Guo-lun, SUN Jian-zhong, WANG Jin-hao, XIA Hai-ping. Luminescent Properties of Porphyrin Doped Poly [2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene][J]. Chinese Journal of Luminescence, 2008,29(2): 259-263
WU Jun, ZHONG Guo-lun, SUN Jian-zhong, WANG Jin-hao, XIA Hai-ping. Luminescent Properties of Porphyrin Doped Poly [2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene][J]. Chinese Journal of Luminescence, 2008,29(2): 259-263DOI:
Luminescent Properties of Porphyrin Doped Poly [2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene]
Organic light-emitting diodes (OLEDs) based on conjugated polymers have been attracting much attention because of their cheap and easy fabrication with solution-based processing techniques. Full color displays based on organic materials have very attractive prospects and one of the most exciting ones is the use of ink-jet printing to allow direct patterning of conjugated polymer LED pixels. However
achieving "pure-red" emission has proved relatively challenging. In this work the optical properties of varying 5
4-phenylenevinylene] (MEH-PPV) were studied. The UV-Vis absorption of Q-band of TTP overlapped the photoluminescent spectra of MEH-PPV. This is a priority for occurrence of Förster-type energy transfer. The photoluminescent spectra of varying TTP doped MEH-PPV showed that the emission of TTP increased as the increasing of the doping level at the excitation wavelength of 500 nm
at which TTP didn't absorb energy
indicating the existence of Frster energy transfer from MEH-PPV to TTP. However
the continuous addition of TTP resulted in the enhanced emission of MEH-PPV at the doping level above 4 percent
due to the self-quenching caused by crystallization of TTP. The devices with varying TTP doped MEH-PPV as light-emitting layers were also fabricated and the structure of the devices was ITO/PEDOT:PSS/TTP doped MEH-PPV/Al[PEDOT:PSS=poly(2
3-dihydrothieno[3
4-b]
-1
4-dioxin)/poly(styrenesulfonate)]. The layers of PEDOT/PSS (20 nm) and TTP doped polymers (80 nm) were spun onto ITO substrates and aluminum cathode (100 nm) was deposited under vacuum pressure of about 1×10
-3
Pa. The electroluminescent properties of the devices were investigated and TTP dominated red emission was observed. The electroluminescent emission from TTP increased as the increasing of doping level in light-emitting layer. On the other hand
the emission of MEH-PPV reduced gra-dually until the doping level of 8 percent. Then it began to grow. The results of photoluminescence and electroluminescence expressed that the two emission processes followed different mechanisms. TTP could be a center for capturing exitons in electroluminescence and the emission of TTP involved the capture of electrons and holes by itself apart from Frster-type energy transfer from MEH-PPV. The researches on TTP doped conjugated polymers will be helpful to enlarge the application of dye
porphyrin
in OLEDs. Moreover
the researches on the mechanisms of photoluminescence and electroluminescence for the blended systems will provide scientific basis for color tuning of composite materials.
关键词
有机电致发光卟啉能量转移
Keywords
organic electroluminescenceporphyrinenergy transfer
references
Chen Chinti.Evolution of red organic light-emitting diodes:Materials and devices[J].Chem.Mater.,2004,16(23):4389-4400.
Huang Chunhui,Li Fuyou,Huang Wei.Introduction to Organic Light-Emitting Materials and Devices(有机电致发光材料与器件导论)[M].Shanghai:Fudan University Press,2005.
Kolosov D,Adamovich V,Djurovich P.1,8-Naphthalimides in phosphorescent organic LEDs:the interplay between dopant,exciplex,and host emission[J].J.Am.Chem.Soc.,2002,124(33):9945-9954.
Shen F,Xia H,Zhang C,et al.Electroluminescence of poly(vinylcarbazole) doubly doped with two phosphorescence dyes:investigation of spectral change as a function of driving voltage[J].J.Phys.Chem.B,2004,108(3):1014-1019.
Li Xinbei,Zhang Fanghui,Zhang Maili.Red doped light-emitting diodes[J].Chin.J.Lumin.(发光学报),2006,27(5):689-694 (in Chinese).
Xu Maoliang,Li Wenlian,Li Mingtao,et al.A new iridium complex with trifluoromethyl-substituted 2-benzo[b] thiophen-2-yl-pyridine ligand and its application in OLEDs[J].Chin.J.Lumin.(发光学报),2007,28(3):433-436 (in English).
Young R H,Tang C W,Marchetti C W.Current-induced fluorescence quenching in organic light-emitting diodes[J].Appl.Phys.Lett.,2002,80(5):874-876.
Iqbal R,Yahioglu G,Milgrom L,et al.Synthesis of porphyrin-PPV copolymers for applications in LEDs[J].Synth.Met.,1999,102(1-3):1024-1025.
Morgado J,Cacialli F,Iqbal R,et al.Frster energy transfer and control of the luminescence in blends of an orange-emitting poly(p-phenylenevinylene) and a red-emitting tetraphenylporphyrin[J].J.Mater.Chem.,2001,11(2):278-283.
Neef C J,Ferraris J P.MEH-PPV:improved synthetic procedure and molecular weight control[J].Macromolecules,2000,33(7):2311-2314.
Zheng M,Bai F,Zhu D.Photophysical process of MEH-PPV solution[J].J.Photoch.Photobio.A,1998,116(2):143-145.
Traiphol R,Sanguansat P,Srikhirin T,et al.Spectroscopic study of photophysical change in collapsed coils of conjugated polymers:effects of solvent and temperature[J].Macromolecules,2006,39(3):1165-1172.
Dykstra T E,Kovalevskij V,Yang X,et al.Excited state dynamics of a conformationally disordered conjugated polymer:A comparison of solutions and film[J].Chem.Phys.,2005,318(1-2):21-32.
You W,Wang L,Wang Q,et al.Synthesis and structure/property correlation of fully functionalized photorefractive polymers[J].Macromolecules,2002,35(12):4636-4645.
Zhang Ting,Xu Zheng,Chen Xiaohong,et al.Energy transfer in the color-tunable organic electroluminescence by voltage modulation[J].Chin.J.Lumin.(发光学报),2001,22(4):347-349 (in Chinese).