Thermochromism of perylene pigments and their application to optical disks

从分子和晶体结构以及分子间相互作用的角度对苝黑颜料的热致变色性能进行了表征，并特别关注了其在光盘中的潜在应用。发现热变色不是由分子结构的变化引起的，而是由温度变化下分子间相互作用的变化引起的。所研究的苝黑颜料具有典型体系的特征，在固态中，由于组成分子的吸收系数大，过渡偶极子之间的相互作用普遍存在。在这种情况下，在可见区出现两个吸收带：一个是由于单个分子（473 nm），另一个是由于激子耦合效应（635 nm）。由于后一波段依赖于分子间相互作用，因此当前波段表现出显著的温度依赖性。这就是苝黑热致变色的机理。在极端情况下，颜色会在红色（“无定形”）和黑色（“结晶”）之间变化。这种颜色变化可以应用于基于635 nm AlGaInP二极管激光器的光盘系统。研制了一种信息存储系统，在激光照射下，在诱导相变的腙化合物存在下，635 nm处的吸收被打开（红→黑）或关闭（黑→红）。

Thermochromic properties of perylene-black pigments have been characterized, with special attention to potential applications for optical disks, from the standpoint of molecular and crystal structures as well as intermolecular interactions. Thermochromism is found not to arise from changes in molecular structure but due to changes in intermolecular interactions under temperature variations. The perylene-black pigments investigated are characteristic of the typical systems, in which the interactions between transition dipoles prevail in the solid state due to large absorption coefficients of the constituent molecules. In this case, there appear two absorption bands in the visible region : one is attributed to individual molecules (473 nm) and the other is due to exciton coupling effects (635 nm). Since the latter band depends on the intermolecular interactions, the present band exhibits a remarkable temperature dependence. This is the mechanism of the thermochromism of the perylene black. In an extreme case, the color changes between red ("amorphous") and black ("crystalline"). This color change can be applied to optical disk systems based on an AlGaInP diode laser of 635 nm. An information storage system has been developed in which the absorption at 635 nm is switched on (red→black) or switched-off (black→red) on irradiation with laser in the presence of a hydrazone compound that induces a phase change.