通过分析有机电致发光器件中载流子注入、输运、激子的解离与复合过程,提出了激子解离与复合的理论模型. 基于电流连续性方程和Poisson方程,给出了激子复合几率、电流密度及复合效率表达式.研究了外加电压和温度对器件中激子的复合几率及在各种接触条件下外加电压对器件电流和复合效率的影响.结果表明:(1)在一个较宽的注入势垒范围内,复合几率随电场和温度的升高而降低;(2)固定阴极势垒,而阳极势垒由小变大时,器件电流由接触限制向空间电荷限制转变;(3)复合效率随外加电压升高先增加,当电压达一临界值时而陡降,并存在一个最佳的注入势垒值.其计算值与所报道的实验结果相符合.
A theory model and complete analytic function for fission and recombination of exci-tons in single layer organic light-emitting devices were presented. The calculated results indicate that (1) the recombination probability of excitons is decreased slowly with applied electric field increasing, and then decreased abruptly when applied electric field reaches a threshold va-lue; (2) the recombination probability of the charge carriers keeps decreasing with temperature but the conversion efficiency of the devices is basically independent of the temperature; (3) the current-voltage characteristics show that fixing the cathode barrier and varying the anode barrier will result in the transition between space-charge-limited and contact-limited current flow. (4) the recombination efficiency is enhanced firstly and then decreased sharply and exists an optimum barrier value as applied voltage increasing. The results could explain the related experimental phenomena.
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