光致发光聚酰亚胺研究进展

聚酰亚胺是一类重要的高性能高分子材料,具有优异的热性能、机械性能、电学性能和尺寸稳定性等,同时具有良好的结构可设计性,已逐渐成为有机光电领域的研究热点.然而,传统聚酰亚胺材料一般不发光,文献中有关发光聚酰亚胺的研究并不多.同时,所报道的荧光量子产率普遍较低,极大地限制了其作为发光功能层在有机光电器件领域的应用.为了更好地了解聚酰亚胺发光的规律,拓展高性能聚酰亚胺材料在有机发光器件中的应用领域,本文介绍了聚酰亚胺光致发光的机理,综述了国内外有关光致发光聚酰亚胺的研究进展,总结了提高聚酰亚胺荧光量子产率的方法,并对未来高性能高效发光聚酰亚胺材料的研究方向做了展望.

Recent Advances of Photoluminescence Polyimides

Polyimides (PIs) are a class of representative high-performance polymers possessing a number of merits,such as high thermal stability,good mechanical and electrical properties,superior dimensional stability,and designable structures.They have important potential applications in the fields of organic optoelectric industries.However,traditional polyimides are in general non-luminescent.Studies of polyimides as light-emitting materials are rare.The photoluminescence quantum efficiency reported is quite low,mainly due to the strong inter-and intra-molecular charge-transfer (CT) interaction of polyimides,which greatly restricts their applications as light-emitting functional layer in the organic optoelectric fields.In order to better understand the general rules of light-emitting behavior of polyimides,and to broaden their application fields in the organic light-emitting diode,this review gives a presentation on the photoluminescence mechanism of polyimides that have been developed,including the formation of locally excited (LE) state and charge transfer (CT) state in the typical donor-acceptor polyimide structures,and the influence for both of the states on their respective photoluminescence process.The recent advances of photoluminescence polyimides as well as the methods to improve the fluorescence quantum yield of polyimides are also provided.Reviewing the polyimides with high photoluminescence quantum yield is focused mainly on the introduction of heterocyclic chromophores (like triphenylamine,pyridine,coumarin,dioxazole,porphyrin etc.) and fused-ring chromophores (like naphthalene,anthracene,pyrene,perylene,fluorene,etc.) into the main chain or the side chain of the aromatic polyimides.These methods would improve more or less the luminescence intensity without sacrificing the comprehensive properties of the polyimides,but there still be a long way to go as the fluorescence may be weakened by the condensed stacking of the chromophores.In another aspect,some researchers also introduced chromophores into semi-aliphatic polyimides,and found it an efficient way to develop highly fluorescent polyimides,because these aliphatic structures in the polymer backbone would effectively limit the intra-CT interactions,and finally form LE emission.However,the overall properties of these semi-aliphatic functional polyimides would be greatly decreased,and their work functions were difficult to match with the metal electrodes,which would greatly limit their applications.Therefore,to obtain the key technologies for the controllable preparation of highly-efficient luminescent polyimides and the controllable adjustment of the luminescent color would be the most important research directions in the near future,which would be of great interest to develop the applications in the fields of photo electronic devices,energy saving and environmental protection forhigh-performance and high-efficiency light-emitting polyimides.