NEW MOLECULES FOR WHITE LIGHT EMITTING DIODES

Emmanuel Santos Moraes; Luís Gustavo Teixeira Alves Duarte; José Carlos Germino (PD) Department of Physics and i3N . Aveiro, Portugal; Teresa Dib Zambon Atvars

All Papers

Submission

Paper Title

NEW MOLECULES FOR WHITE LIGHT EMITTING DIODES

Authors

Emmanuel Santos Moraes
Luís Gustavo Teixeira Alves Duarte
José Carlos Germino (PD) Department of Physics and i3N . Aveiro, Portugal
Teresa Dib Zambon Atvars

Modality

Pôster

Subject area

Dispositivos eletrônicos e ópticos (OLED/OFET/OPVs/etc.)

Publishing Date

12/12/2023

Country of Publishing

Brasil

Language of Publishing

Inglês

Paper Page

https://www.even3.com.br/anais/workshop-do-ineo-2023/613904-new-molecules-for-white-light-emitting-diodes

ISBN

978-65-272-0088-8

Keywords

organic light emitting diodes, white emission, ESIPT compounds, coordination compounds, all-solution OLEDs

Summary

White emitting diodes using organic molecules or organic polymers have been studied world wile. In general, the active layers of these diodes were build using different strategies: multi component polymer blends, multi layers with different molecules (blue-green-red), one component with non-interacting chromophores (blue-green-red), internal EL/external PL layers (blue to red trivial transfer). The challenges are always to improve the performance, having stable compounds. In recent years, we are adopting a different strategy. We are looking for simple molecules, easily synthetized, with double emissions covering the entire visible spectrum. A particular case of such molecules is that depicting excited state intramolecular proton transfer (ESIPT). These molecules have two emission bands, a higher energy one due to the normal molecule and a lower energy band due to the ESIPT. Two small molecules (salicylidene-4,6-(dimethylamino)pyridine andalicylidene-5-bromo-4,6-(dimethylamino)pyridine) provided proof for this concept (https://dx.doi.org/10.1021/acs.jpcc.0c07178) The disadvantage of these molecules is that the diode performance is very poor as in general for single OLED using all-solution processes preparation, due to the lower charge mobility. Nevertheless, the performance can be improved substantially by complexing these molecules using a metal ion, forming coordination compounds. The drawback of complexing is that it blocked the ESIPT process, leaving only the higher energy band visible. By selecting stable, affordable and abundant metal centers, this issue is partially resolved by dissolving the coordination compounds (guest) in a host matrix (conjugated emissive polymer). Using Zn(II) coordinated to salophen, benzoyl decorated salophen and benzothiazol decorated salophen (https://doi.org/10.1021/acs.jpcc.0c04126) and Pt(II) metal centers coordinated to salophen and to benzophenone decorated salophen (https://doi.org/10.3390/nano12142497) in a PFO host, with molar maximum proportion of 1%, very promising all-solution processed diodes were tested. Performances using the PT(II) compounds in a single layer all-solution processed diode were: 2.2% and 15.3% of external quantum efficiencies, with luminances of 3103 cd/m and 6224 cd m/2 for the [Pt(salophen)] and [Pt(sal-3,4-ben)] complexes, respectively. Our research led to some conclusions: coordination compounds perform better in diodes than their corresponding ligands, however white emission necessitates the insertion of a band from the PFO conjugated polymer. Moreover, to avoid dye aggregation in the host/guest system, the concentration of the coordination must be restricted to up to 1% in all-solution produced diodes. Due to the presence of triplet states, Pt(II) coordination compounds performed significantly better than Zn(II) diodes.

Title of the Event: Workshop do INEO 2023
City of the Event: Nazaré Paulista
Title of the Proceedings of the event: Anais do Workshop INEO 2023
Name of the Publisher: Even3
Means of Dissemination: Meio Digital

How to cite

MORAES, Emmanuel Santos et al.. NEW MOLECULES FOR WHITE LIGHT EMITTING DIODES.. In: Anais do workshop INEO 2023. Anais...Nazaré Paulista(SP) Hotel Estância Atibainha, 2023. Available in: https//www.even3.com.br/anais/workshop-do-ineo-2023/613904-NEW-MOLECULES-FOR-WHITE-LIGHT-EMITTING-DIODES. Access in: 12/05/2025