Photo-EMF measurements on highly ordered layers of a cyanine dye
Photo-EMF measurements on highly ordered layers of a cyanine dye
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DOI：
10.1039/b105295k
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发表时间：
2001-12
影响因子：
3.3
通讯作者：
C. Damm;L. Dähne;F. W. Müller
中科院分区：
文献类型：
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作者：
C. Damm;L. Dähne;F. W. Müller
制备了一种新型的1，7-双-（N，N-二甲氨基）七甲川高氯酸盐薄层，在这种薄层中，分子像单晶一样在扩展的区域内均匀取向。通过改变制备工艺，可以形成（010）和（201）两种不同的晶面。在这些层上的光电动势（PEMF）的时间分辨的测量使用的Dielectric效应。通过改变层中光学跃迁与偏振入射光振动方向之间的角度α，可以简单地控制次表面和体中闪光产生的电荷载流子的数量。这导致不同的光穿透深度，随后是角度依赖性PEMF。双指数PEMF衰减的结果从两个不同的失活过程。由子表面中载流子的高复合率引起的快速过程取决于角度α，而在体材料中发生的缓慢过程几乎与该角度无关。PEMF还取决于哪个晶面被照射。这可以解释为沿着紧密堆叠的染料分子的较高的电荷载流子迁移率或所涉及的激子态的不同能量。
A new type of thin layers of 1,7-bis-(N,N-dimethylamino)heptamethineperchlorate was prepared in which the molecules are oriented uniformly in extended areas, like in single crystals. By modifying the preparation process, two different crystal faces (010) and (201) could be developed. On these layers time-resolved measurements of the photo-electromotive force (PEMF) were made using the Dember effect. The number of flash-generated charge carriers in the subsurface, and in the bulk could be controlled simply by changing the angle α between the optical transition in the layer and the vibration direction of the polarised incident light. This results in a different depth of light penetration, followed by an angle-dependent PEMF. The biexponential PEMF decay results from two different deactivation processes. The fast process, caused by a high recombination rate of carriers in the subsurface, depends on the angle α whereas the slow process taking place in the bulk material is almost independent of this angle. The PEMF depends also on which crystal face is illuminated. This may be explained by the higher charge carrier mobility along the closely stacked dye molecules or by the different energy of the exciton states involved.