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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。
By analyzing carrier injection, transport and exciton dissociation and recombination processes in organic electroluminescent devices, a theoretical model of exciton dissociation and recombination is proposed. Based on the current continuity equation and the Poisson equation, the expressions of recombination probability, current density and recombination efficiency of excitons are given. The effects of applied voltage and temperature on the recombination rate of excitons in the device and the applied voltage on the device current and recombination efficiency under various contact conditions were investigated. The results show that: (1) the recombination probability decreases with the increase of electric field and temperature over a wide range of implanted barrier; (2) when the potential barrier of anode increases from small to large, (3) The recombination efficiency first increases with the increase of applied voltage, then decreases sharply when the voltage reaches a critical value, and there exists an optimal value of the injected barrier. The calculated value is consistent with the reported experimental results.