绝缘层LiF/Al电极对提高P-PPV发光器件发光性能的研究

为了提高聚合物电致发光器件中Ba（Ca）／Al阴极的稳定性，在该阴极与聚合物发光材料poly（2-（4-ethylexyl）phenyl-1，4-phenylene vinylene）（P-PPV）层之间插入一层7nm的LiF绝缘层，发光器件的发光性能在多项参数（发光器件的电压．电流特性、发光强度及外量子效率，以及电流效率等发光性能指标）上能够与工作性能优良但稳定性较差的Ba（Ca）／Al电极结构PLEDs器件的发光特性具有可比性。这对于研制高效率、高稳定的聚合物电致发光器件并最终将其用于商业目的，具有重大现实意义。

Performance Improvement of P-PPV Light-emitting Diodes with Metal Fluoride Cathode

The electronic and optical performances of P-PPV light-emitting diodes with lithium fluoride insulating layer between the metal cathode and active polymer are studied. As for the polymer light-emitting diodes, optimization of charge injection lies in the dominant factors for substantive improvement performance. Since the minority carriers dominate the recombination thus the radiation, their injection takes priority over that of (majority) carriers. Generally in semiconducting polymers, holes are majority carriers while electrons are the (minority,) the carrier misbalance between electrons and holes further deteriorate in the fact that holes usually take possession of higher mobility and smaller injection barrier. To balance injection charge carriers and facilitate the (electron) injection, there are two commonly stratagems to be used in cathode fabrication. One is to employ low work function metals such as barium and calcium as cathode though they are susceptible to degradation upon water vapor and oxygen. The other choice is proposed to insert an insulating thin layer of lithium fluoride (between) polymer/electrode interfaces to build a bilayer cathode. As shown by the experiment results, the LiF/Al double-layer-cathode with Ba(Ca)/Al electrode devices can improve in luminescence performance. Band bending and injection potential decrease of minority carrier caused by the inlay of metal fluoride insulating (layer,) which is proposed to be responsible for the enhanced electron injection and improved performance in polymer light (emitting ) diodes.