顶发射聚合物发光二极管的出光率分析

Analysis of Light Out-Coupling Efficiency in Top-Emitting Polymer Light-Emitting Devices

采用传输矩阵法及Matlab软件模拟以聚合物MEH-PPV为发光材料的顶发射聚合物发光二极管(TEPLED)出光率,探讨了阳极材料、阴极材料、折射率匹配层以及发光角度等对器件出光率的影响。从仿真结果可知以传统分布布拉格反射器(DBR)为衬底的器件与以Ag膜为反射阳极的器件相比,表现出更高的出光率,达到47.43%。针对半透明金属阴极对光线的吸收和反射问题,设计了以透明材料为阴极的器件,提高了TEPLED出光率,达到67.11%,与以Ag膜为阴极的器件相比,出光率高出10%。分析了DBR对器件出光角度的影响,结果表明,器件在较小出光角度范围(30°)内DBR结构对整个TEPLED出光率影响较小;当角度大于30°时,器件出光率受DBR的反射特征影响较大。DBR的应用为TEPLED出光率的优化设计提供了理论依据。

The light out-coupling efficiency of top-emitting polymer light-emitting devices （TEPLED） based on poly [2-me-thoxy-5-（2-ethyl-hexyloxy）-l, 4-phenylenevinylene] （MEH-PPV） is simulated by applying the transfer matrix method and software Matlab. The influence of anode materials, cathode materials, capping layers and observing angle on the performance of the TEPLEDrs out-coupling efficiency is studied. When compared with Ag film anode device, the one based on distributed Bragg reflector （DBR） presents higher out-coupling efficiency, reaching 47.43 %. To decrease the light absorption and reflection by sub-transparent metal, transparent materials cathode is designed so that the light-coupling efficiency raises about 10 % compared with Ag anode devices, reaches 67. ll %. The influence of DBR on the observing angles of total TEPLED is studied. The results show that it has little effect on light-coupling efficiency of TEPLED by DBR when the observing angle changes in a narrow range （30°）. It has more effect on lightcoupling efficiency when the observing angle is more than 30°. The application of DBR provides a theoretical basis for the optimization of out-coupling efficiency of TEPLED.