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Electro-optic properties of exciplex-type organic electroluminescence devices depending on the technologies of active-layer preparation

Ivaniuk K., Chapran M., Cherpak V., Barylo G., Stakhira P., Hotra Z., Hladun M. and Dudok T.

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Abstract. We have studied electroluminescence and impedance properties of exciplex-type organic light-emitting devices (OLEDs) based on 4,4,4″ - tris[3- methylphenyl (phenyl)- aminotriphenylamine (m-MTDATA) and 4,7- diphenyl-1,10- phenanthroline (Bphen), which depend on the technologies applied to form active layers of the devices. A comparative analysis of the current–voltage characteristics and impedance spectroscopy of the layered and composite devices have revealed the influence of device technology on the injection of charge carriers in the active layers of OLED structures. We have found a correlation between the negative capacitance observed at low frequencies in the exciplex-type layered OLEDs and the emitting recombination processes. 

Keywords: organic light-emitting devices, exciplex, impedance spectroscopy, negative capacitance

PACS: 72.40.+w
UDC: 621.38
Ukr. J. Phys. Opt. 16 95-102
doi: 10.3116/16091833/16/2/95/2015
Received: 24.04.2015

Анотація.  Досліджено електролюмінісцентні і  імпедансні властивості органічних світлодіодів ексіплексного  типу на основі 4,4,4 "трис [3-метилфеніл (феніл) -амінотрифениламін (м-MTDATA) і 4,7-діфеніл- 1,10-фенантроліна (Bphen), які залежать від використаних технологій при формуванні активних шарів пристроїв. На основі порівняльного аналізу вольт-амперних характеристик і імпедансної спектроскопії пошарових і композиційних пристроїв виявлено вплив технології виготовлення пристрою на інжекцію носіїв заряду в активні шари світлодіодних структур. Встановлена кореляція між негативною ємністю та випромінювальними процесами рекомбінації, яка спостерігається в області низьких частот пошарових органічних світлодіодів ексіплексного типу 
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