形成电压对直流电致发光(DCEL)器件在交流(AC)条件下亮度和寿命的影响

实验结果表明,不同形成电压的样品的起始亮度和工作寿命按高低的排列顺序随工作电压的增加表现出有规律的变化。还发现形成电压不问的DCEL器件在AC条件下的发光特性随工作电压的提高逐渐趋向一致,形成电压的影响逐渐消失。这一现象被解释为是由于在AC条件下也存在类似于在直流(DC)条件下的形成过程,即Cu+迁移过程。老化过程也是形成过程的继续。

INFLUENCE OF FORMING VOLTAGE ON THE CHARACTERISTICS OF DIRECT-CURRENT ELECTROLUMINESCENT (DCEL) DEVICES OPERATED UNDER ALTERNATING-CURRENT (AC) VOLTAGE

The influence of forming voltage on the ACEL characteristics of ZnS:Mn, Cu powder DCEL devices is investigated.The samples of DCEL device were formed under 100, 115, 130, 145 and 160 volts respectively, and then operated under AC voltage of 50Hz. The operation voltage was risen from 55 to no volts step by step, At each step, the samples were excited simultaneously in the same period for several hundred hours. In the meantime the brightness and current were recorded.The results from experiments are analyzed and the influence of forming voltage on the two most important parameters, that is the initial and the final brightness at different operating voltage is studied.The experimental results show that the order of arrangement of the initial and the final brightness from lower to higher changes regularly with the increased forming voltage and operating voltage. At the lower operating voltage, the lower the forming voltage, the higher the brightness is. With increasing operation voltage, the order of arrangement of the initial and the final brightness is regularly reversed gradually.An interesting and important property is discovecl. This property shows that the state tends to, be identical with increasing AC operation voltage for DCEL samples formed under various DC voltage. It also means that the higher the AC operation voltage,the less the influence of forming voltage on ACEL characteristics of DCEL devices is. For this reason, the difference in ACEL for samples formed under different voltage decreases with the increase of operation voltage and at last the ACEL characteristics tend to be the same. The phenomenon is considered that Cu+ migration happens under AC operation, which is just like that under DC operation.