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

1.激光烧蚀制备有机薄膜的结晶性改善由于迁移增强，衬底温度的轻微升高可以导致通过激光烧蚀沉积制备的薄膜结晶性的显著改善。在-1mW/cm^2的非常弱的HeNe激光照射也可以有助于增强表面迁移，从而产生更好的结晶CuPc薄膜，其在可见波长处表现出显著的吸收。当基片晶场很强时，沉积在基片上的薄膜倾向于沿着一个确定的方向取向，这种温度效应增强了基片对薄膜自然取向的影响;另一方面，在基片上形成薄膜时，具有高极化率的分子可以被外电场控制。在外加电场的作用下，在Si衬底上制备的酞菁铜薄膜的结晶度得到了显著的提高。然而，在薄膜形成过程中，晶场的影响远大于这种极化效应。2.酞菁铜薄膜的电学特性测量了不同堆叠度的酞菁铜薄膜的电导率。非晶薄膜在厚度方向上表现出较好的导电性，这更适合于电致发光器件，而在电场下沉积的结晶薄膜沿膜表面沿着表现出较高的导电性。我们测量了CuPc/Alq 3电致发光电池的近场发射图案，其结晶度用HeNe激光照射局部改善。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.