材料期刊网

描述了评价有机电致发光性能的重要指标——发光效率问题。 从发光机制考虑， 一般常用外量子效率和内量子效率来评价。 外量子效率是有机电致发光器件输出光子数与注入电子数之比； 内量子效率是产生在器件内部的光子数与注入电子数之比， 对于光子能否输出到器件外部无关紧要。 评价器件性能还有一些其他效率评价方法， 如能量效率、 功率效率等， 特别是外功率效率（lm/W）、 电流效率（cd/A）也常常用于表征有机电致发光性能， 但它们与发光光谱的视觉灵敏度有关， 对紫外和红外辐射器件不适用。 另外， 利用三重态激子发射可以提高EL器件效率， 理论上可达100%； 器件结构及材料对器件外量子效率影响至关重要。

One of the important specifications of luminescent efficiency is described. Under electroluminescent mechanism, external quantum efficiency and internal quantum efficiency are used to evaluate the organic electroluminescent properties. The external quantum EL efficiency, ηφ(ext) is defined to be the ratio between emitted photon number outside of a device and apparent number of charge injected into a device, and the internal quantum efficiency, ηφ is defined to be the ratio between photon number produced within a device and apparent number of charge injected into a device, but it is not so important whether the photons can emit outside a device or not. Other approaches evaluating efficiency have been also used, such as energy efficiency, power efficiency etc., especially external power efficiency (lm/W) and current efficiency (cd/A). They can be used to characterize organic electroluminescence which is intensively related to visual sensitivity, but can not be used for ultraviolet and infrared EL devices. On the other hand, using emission from triplet excitons, the efficiency of organic EL devices can be increased to 100% theoretically. The experimental results show that the effect of device structures and materials on external quantum efficiency is also very important.