Organic electroluminescence cells fabricated by a novel laser ablation scheme with selective thin film growth

1.激光烧蚀有机薄膜结晶度的提高提高衬底温度可以显著提高激光烧蚀沉积薄膜的结晶度，这是因为薄膜的迁移性增强。在-1 mW/cm2的He-Ne激光照射下，CuPc薄膜的表面迁移率提高，薄膜的晶化程度提高，在可见光区表现出明显的吸收。当衬底晶场很强时，沉积在衬底上的薄膜倾向于沿规定的方向取向，这种温度效应增强了衬底对自然取向的影响，另一方面，在衬底上形成薄膜的过程中，具有高电极化率的分子可以受到外部电场的控制。在外加电场的作用下，在硅衬底上制备的CuPc薄膜的结晶度显著提高。2.CuPc薄膜的电学特性测量了不同结晶度的CuPc薄膜的电导率。非晶态薄膜在厚度方向上表现出较好的导电性，这对电致发光器件是有利的，而在电场作用下沉积的晶态薄膜沿薄膜表面具有较高的导电性。我们测量了CuPc/Alq3电致发光电池的近场发射图案，其中结晶度在HeNe激光照射下得到了局部改善。然而，电导率的差异仍然不足以产生局部电流。

1.Crystallinity Improvement for Organic Thin Films Fabricated via Laser AblationSlight elevation of substrate temperature can induce significant improvement on the thin film crystallinity fabricated via laser ablation deposition because of the migration enhancement. Very weak HeNe laser irradiation at -1mW/cm^2 can also contribute to enhance the surface migration resulting in better crystalline CuPc thin films, which exhibits significant absorption at the visible wavelength. When substrate crystal field is so strong that thin film deposited on the substrate tends to align along a defined direction, this temperature effects enhance the natural orientation affected by the substrate.On the other hand, molecules that hold high electric polarizability can be controlled by external electric field during the thin film formation on a substrate. The crystallinity of CuPc thin films fabricated on a Si substrate is drastically improved with an external electric field. However, he effect of crystal field is much higher than this electric poling effect during the thin film formation.2.Electric Characteristics of CuPc Thin FilmsElectric conductivity was measured for CuPc thin films with various crystallinities. Amorphous thin films exhibit better conductivity in the direction of thickness, which is better for electroluminescence devices, while the crystalline thin films deposited under electric field show higher conductivity along the film surface. We measured a near field emission pattern of CuPc/Alq3 electroluminescence cells, of which crystallinity was locally improved with HeNe laser irradiation. However, the difference in the conductivity is still not high enough to generate localized current flow.