Organic electronics, mainly due to advancements in OLED (Organic Light Emitting Diode) technology, is a fast developing research area having already revolutionized the displays market. This project will demonstrate the use of thermally activated delayed fluorescence (TADF) and Room Temperature Phosphorescence (RTP) emitters in high-efficiency OLEDs, that are stable and do not use scarce and expensive materials such as iridium. The proposed project deals with the comprehensive task of synthesis and analysis of novel ambipolar compounds containing carbazole, phenothiazine, phenoxazine, acridine etc. with different acceptor units based on phenazine, arylene bisimide, diphenylphosphine and dibenzoselenophene Se, Se-dioxides groups, characterization of these compounds and the construction and testing of warm white OLED devices.

The rapid development of molecular electronics effect on lowering the cost of production of optoelectronic circuits like OLED displays. On the other hand, the high demand for thin-film, flexible matrix OLED contributed to the increase in demand for rare and very expensive iridium, which is the main component of typical phosphorescent emitters. In order to eliminated iridium based compounds, scientists began to look for another way to increase the efficient emitters. From a physical point of view, the luminescence process can be divided into two processes fluorescence and phosphorescence, where the first is a rapid process in which the molecule from the singlet excited state returns to the ground state by emitting energy in the form of photons. Phosphorescence is a long lived process associated with moving molecules from singlet excited state to the triplet state. This transition is a quantum forbidden transition and for that the process of Intersystem Crossing (ISC) takes longer. Then, excited triplet state of the molecule relaxes to the ground state. Inside the organic light emitting devices (OLED) after applying potential (charge), electrons and holes in the active substance can be combined to form different excited states, such as the singlet excitonic state and triplet excitonic state. When the charge singlet excitons and triplet, which should theoretically be produced in a ratio of one to three, are formed. In the case of devices based on the fluorescence emission process of fluorescence emission is caused only by the decay of singlet excitons, the state of triplet exciton is prohibited. Quantum yield for singlet excitons is limited to 25%, which means that the triplet excitons is 75%. So far, in the industry one of the ways to improve the process efficiency of light was the use of the phosphorescence process and forming PHOLEDs (Phosphorescence Organic Light-Emitting Diodes). Unfortunately, efficient phosphorescence emitters contain a very expensive iridium and quantum efficiency of real devices is below 15% and the operating voltage above 4 V, which results in a large loss of energy and a shorter lifespan. The innovative idea to increase device efficiency, is to link the process of fluorescence and phosphorescence and to obtain 100% yield by employing the E-type delayed fluorescence (E-DF) also called TADF (Thermally Delayed Fluorescence Activated). In general terms, it means that the molecule from the triplet excited state is going back to the singlet excited state, and then relaxes to the ground state by emitting photons. In this process, excited singlet state and a triplet must have very similar energies. Thanks to that with small amount of energy, molecule is able to move from the triplet excited state back to the singlet excited state, and relax with emission of light. The maximum yield of this process is 100%.
In my project, I will try to use the thermally activated delayed fluorescence (TADF) process for various mixed layers of donor-acceptor (exciplex) as OLED emitter and studied the influence of morphology and thermal properties of layers on emission in order to improve efficiency up to 100% (more than 15% EQE). Such stable systems will help in the future eliminate expensive iridium based compounds in diodes and OLED displays.

The overall aim of the project is to create a new international EU-World Network concentrated on organic charge transfer processes and applications. To fulfill this scientific purpose we will form the network from partners which are excellent by themselves in their area of expertise. The network is composed of the Silesian University of Technology (SUT, Poland), University of Durham (UDUR, UK), University of Glasgow (UoG, UK), University of Dusseldorf (UOD, Germany), Universidade Federal de Santa Catarina (UFSC, Brazil), National Taiwan University (NTU, Taiwan) and Osaka University (OU, Japan). To achieve this aim, the four year project will be built upon the existing strong science and innovation base of all partners.

The overall aim of the project is to boost the scientific excellence and innovation capacity in organic electronics of the Silesian University of Technology (SUT) by creating a network with the high-quality Twinning partners: University of Durham (UDUR), Institute of Nanoscience and Cryogenics, Commissariat à l’Energie Atomique et aux Energies Alternatives (INAC) and Eindhoven University of Technology (TUE). To achieve this aim, the three year project was build upon the existing strong science and innovation base of chosen universities and research institutions.

EXCILIGHT is an Innovative Training Network (ITN), funded as part of the Marie Skłodowska-Curie Actions of the European Union's Horizon 2020 Research and Innovation Programme. The project's objective is to train the next generation of bright young scientists by tackling major research projects.

Our network will train 15 Early Stage Researchers (PhD students) in the development and application of exciplex and TADF (Thermally Activated Delayed Fluorescent) emitters, who will be able to apply their expertise directly in future positions. EXCILIGHT is characterised by an innovative multidisciplinary approach, based on

a combination of synthesis, physical characterisation and development of devices with the lighting industry,
an appropriate balance between research and transferable skills training, and
a strong contribution from the private sector, including leading industry and SMEs, through mentoring, courses and secondments.