Publication date: 8th January 2019
In this study, we report on unique application of donor-acceptor (D-A) derivatives of carbazole and quinoline as versatile exciplex-forming materials which can form two different types of exciplexes D-A/D and A/D-A at the same time. The synthesized bipolar D-A molecules formed blue to orange emitting excited complexes (exciplex type 1: D-A/D) with electron-donating compounds and blue exciplexes (exciplex type 2: A/D-A) with electron-accepting materials. As a result, white electroluminescence was observed by mixing blue and orange exciplex emission in the system consisting of the synthesized derivative of quinoline and carbazole in pair with acceptor 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T) and in combination with donor 4,4′,4′′-tris[3-methylphenyl(phenyl)amino]- triphenylamine (m-MTDATA), respectively.
For development of highly efficient white organic-light-emitting diodes (WOLEDs), exciplex-forming materials have to be characterized at least by high triplet energies, bipolar charge transport, and HOMO and LUMO levels appropriate for hole and electron injection. These requirements were partly met by the studied D-A compounds. WOLEDs based on two blue and orange interface exciplexes which were formed between three non-doped layers (A/blue interface exciplex/D-A/orange interface exciplex/D) were fabricated. In the fabricated WOLEDs, non-doped layer with the different thicknesses of D-A compound acted as emitter forming two interface exciplexes as well as hole- and electron- transporting modulator resulting in different distribution of holes and electrons at these two interfaces. Therefore, different white colour was recorded for devices with the same structure but with different thicknesses of the functional layers.
To the best of our knowledge, this is the first report on utilization of the same D-A compounds as donors and as acceptors in exciplex-forming systems for achieving white light. White non-doped three-layer sandwich-type device demonstrated high colour rendering index of 76, colour temperature of 8400 K and maximum external quantum efficiency of 3.15 %.
This work was supported by Research Council of Lithuania (Project “OWEX” No S-MIP-17-101).
nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.
Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.
International Conference on Hybrid and Organic Photovoltaics
International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.
Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.
The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.