Improved film morphology and reduced defects in solution-processed red phosphorescent emission layer of the organic light-emitting diodes

•The process of fabricating OLEDs by solution process is simple and saves costs.•We use chlorobenzene and isopropanol as mixed solvents to reduce the roughness and the defect states of the EML.•The performance of the device improved with a high EQE up to 17.2% and current efficiency up to 27.1 cd/A,...

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Bibliographic Details
Published inSynthetic metals Vol. 261; p. 116322
Main Authors Zhou, Lin, Xu, Zheng, Song, Dandan, Zhao, Suling, Qiao, Bo, Chen, Junfei, Zheng, Weiye
Format Journal Article
LanguageEnglish
Published Lausanne Elsevier B.V 01.03.2020
Elsevier BV
Subjects
Chlorobenzene
Current efficiency
Electroluminescence
Light emitting diodes
Mixed solvents
Morphology
Organic light emitting diodes
Organic materials
Phosphorescence
Production costs
Quantum efficiency
Red phosphorescent
Solution-processed
Solvents
Red phosphorescent
Mixed solvents
Morphology
Solution-processed
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Summary:•The process of fabricating OLEDs by solution process is simple and saves costs.•We use chlorobenzene and isopropanol as mixed solvents to reduce the roughness and the defect states of the EML.•The performance of the device improved with a high EQE up to 17.2% and current efficiency up to 27.1 cd/A, respectively. The fabrication of highly efficient organic light-emitting diodes (OLEDs) by solution processes has become a hot research point due to the low production cost, high material utilization ratio and simple fabrication process. Herein, highly efficient, solution-processed red phosphorescent organic light-emitting diodes (PhOLEDs) using chlorobenzene (CB) and isopropanol (IPA) as mixed solvents are proposed. It is found that both the roughness and the defect states of emission layer (EML) prepared with mixed solvents are reduced. Thereby, the electroluminescence performance of PhOLEDs are enhanced compared with that of the ones with pure CB as the solvent. With CB:IPA ratio of 5:1, the current efficiency and the external quantum efficiency of device reach 27.1 cd/A and 17.2 %, respectively. These results prove that the use of IPA can improve the device performance even if it is not able to dissolve the organic materials, which breaks the limitation of the use of alcohol solvent in solution-processed OLEDs.
ISSN:0379-6779
1879-3290
DOI:10.1016/j.synthmet.2020.116322