不同形态MEH-PPV的构象及其光学特性

通过对在固溶体、稀溶液、薄膜和纳米孔中MEH—PPV的PL和PLE谱的测量分析，研究不同形态下MEH-PPV分子链的构象及其对电子能带和光学性质的影响。在THF稀溶液中，MEH—PPV分子链基本上皆为分立态；在MEH—PPV薄膜中，分子链基本上皆为聚集态；在MEH-PPV／PS固溶体中，MEH—PPV分子链为聚集态和分立态两构象并存，聚集态的比例随MEH-PPV浓度的增加而升高；在多孔氧化铝模板纳米孔中，MEH—PPV分子链形成链束。分立态、聚集态和链束这三种不同构象的分子链具有不同的电子能带结构和光学性质。

Conformations and Optical Characteristics of MEH-PPV with Different States

Conformations have a large impact on the optoelectronic properties for conjugated polymers.The conformations and electronic states as well as optical characteristics of MEH-PPV chains in solid solution,dilute solution,film and nanopore have been investigated with PL and PLE spectra The following conclusions have been obtained.The MEH-PPV chains are separated basically in THF(tetrahydrofuran) dilute solution.The MEH-PPV chains are aggregated basically in MEH-PPV solid film.There are two conformations of MEH-PPV chains,separated and aggregated conformations,in MEH-PPV/PS solid solution.The aggregated conformation of MEH-PPV increases with increase of MEH-PPV density in MEH-PPV/PS(polystyrene) solid solution.The MEH-PPV chains form chains bunch in nanopores of porous anodic alumina template.The electronic state and optical characteristics are different for separated and aggregated MEH-PPV chains as well as MEH-PPV bunch.The electronic energy band and the band width of PLE spectra are the widest,and then the energy positions of PL spectra peaks are lowest(about 594 nm) for the aggregated conformation states.On the contrary,the electron energy band and the band width of PLE spectra are narrowest,and then the energy position of PL spectra peaks are highest for the separated conformation states.