摘要
研究了在聚(2-甲氧基,5-(2′乙基-己氧基)-对苯乙炔)(MEH-PPV)中掺杂不同质量分数的四对甲基苯基卟啉(TTP)薄膜材料的光致发光和电致发光性能,结果表明,在这个复合体系中存在着从MEH-PPV到TTP的Frster能量转移,从而导致了强的TTP的饱和红光发射。另一方面,在电致发光中TTP的发射除了来自于从MEH-PPV的能量转移外,还来自于自身对载流子的捕获,TTP掺杂的MEH-PPV组成的薄膜复合材料的光致发光和电致发光过程遵循不同的机理。
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 5,10,15,20-tetra-ptolyl-21H, 23H-porphine （TIP） doped poly [ 2-methoxy-5- （ 2＇-ethylhexyloxy ） -1,4-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 Forster-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 TIP didn＇ t absorb energy, indicating the existence of Forster 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 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 TIP increased as the increasing of doping level in light-emitting layer. On the other hand, the emission of MEH-PPV reduced gradually 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 Forster-type energy transfer from MEH-PPV. The researches on TIP 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.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2008年第2期259-263,共5页
Chinese Journal of Luminescence
基金
宁波市自然科学基金(2006A610068)
浙江大学宁波理工学院人才引进基金资助项目
关键词
有机电致发光
卟啉
能量转移
organic electroluminescence
porphyrin
energy transfer
