有机场致发光中能带模型与分子理论的讨论

在有机场致发光中,能带模型及分子理论从20世纪就存在尖锐的矛盾。在分层优化方案中,经SiO₂加速后的电子能量可以到达10eV,这足以激发发光材料发光,将分层优化方案应用到有机场致发光材料中。发现了固态阴极射线发光(SSCL),经过对它的交叉证明、普适性的验证,肯定了固态阴极射线的发光确实是在发光二极管,无机及有机场致发光之外的一种完全新型的电场诱导的发光。SSCL的特征是在它的光谱中出现短波发光峰,实验证明长波发光峰的减弱是由于电场离化效应。研究了这种效应出现的电压阈值并和SSCL的短波峰出现的电压相比,发现短波峰的出现是在激子的电场离化之后,从而找出了电子处于局域态与扩展态的分水岭,解释了在有机场致发光中能带模型和分子理论并不矛盾,只是适用的条件不同。激子的离化是随电场强度而渐进的变化,因此会有一个两种过程并存的范围。

Dispute between Molecular and Band Theory in Organic Electroluminescence

The dispute between molecular and band theory arose from the very beginning of extended study of (organic) electroluminescence. We investigated the layered optimization scheme for inorganic electroluminescence and (obtained) the experience of acceleration ability of SiO_2 being greater than 10 eV, which is large enough to excite an (electroluminescence) materials. We discovered solid state cathodoluminescence by means of this frame and used the newly discovered solid state cathodoluminescence to study the blue spectral shift when the applied voltage is increased. We found three different kinds of spectra in three consecutive intervals of applied voltage. We found that the field ionization of excitons plays a very important and critical role in this blue shift. The switching on of short wavelength emission (recombination radiation) starts only after the beginning of this field ionization. The exciton emission obeys molecular theory and the recombination obeys energy band theory. Thus their demarcation is the appearance of field ionization of excitons. Since the ionization is changing with electric field continuously, there is a region of (coexistence) of these two processes.