WHITE LIGHT GENERATION THROUGH EXCIPLEX AND DOWN-CONVERSION MECHANISMS FOR ORGANIC SOLID-STATE LIGHTING
"This work reports the experimental study of two mechanisms, exciplex and down-conversion, to obtained white light with organic and hybrid materials for solid-state lighting (SSL). Exciplexes are complex states generated by intermolecular interaction between two molecules, usually an electron d...
| Autor: | |
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2020 |
| País: | México |
| Institución: | Centro de Investigaciones en Óptica |
| Repositorio: | Repositorio Institucional CIO |
| Idioma: | inglés |
| OAI Identifier: | oai:cio.repositorioinstitucional.mx:1002/1206 |
| Acceso en línea: | http://cio.repositorioinstitucional.mx/jspui/handle/1002/1206 |
| Access Level: | acceso abierto |
| Palabra clave: | info:eu-repo/classification/Autor/Organic semiconductors info:eu-repo/classification/Autor/Down-conversion info:eu-repo/classification/Autor/OLEDs info:eu-repo/classification/Autor/Exciplex info:eu-repo/classification/Autor/Solid-state lighting (SSL) info:eu-repo/classification/Autor/CIE info:eu-repo/classification/cti/1 info:eu-repo/classification/cti/22 info:eu-repo/classification/cti/2209 info:eu-repo/classification/cti/220908 |
| Sumario: | "This work reports the experimental study of two mechanisms, exciplex and down-conversion, to obtained white light with organic and hybrid materials for solid-state lighting (SSL). Exciplexes are complex states generated by intermolecular interaction between two molecules, usually an electron donor and an acceptor material; they were studied in the OLED structure: ITO/HTL/EML/ETL/Ca-Ag. Commercial materials and a new carbazole derivative were employed as the emissive layer (EML), and for the first-time, exciplex emissions from two interfaces were achieved. The thickness of the hole transport layer (HTL) was a determinant parameter for the exciplex states formation at HTL/EML interface. Meanwhile, the appropriate barrier energy between LUMO levels of the EML and ETL was crucial in allowing the bimolecular states to emerge at the EML/ETL interface. Therefore, due to emissions from the EML (S1-S0 transitions) and the two interfaces, a broad electroluminescence spectrum corresponding to white light with excellent CIE (0.31, 0.33) and CRI >85 was accomplished. The devices exhibited acceptable luminance (< 9000 cdm-2) and turn-on voltage (5 V). On the other hand, the studied down-conversion mechanism involved the full or partial absorption of the light emitted from an inorganic LED by the organic material. Thicknesses of the organic films were optimized to obtain a proper absorption of the converter material, which allowed the adequate combination between the electroluminescence (EL) and photoluminescence (PL) intensities from LED and the organic converters, respectively. Thus, the mechanism was tested in partial and full conversion configuration known as luminesce converter (LUCO). Using benzothiadiazole derivatives as organic converter, LUCO devices exhibited white light with excellent CIE (0.32, 0.33), outstanding CRI (>90) and good conversion efficiency of 73%. With these results, it was demonstrated that organic materials could be a real alternative in the field of SSL." |
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