The mechanism studied by the researchers involves reversible transfer of hydrogen atoms - that is, the transfer of their cation nuclei - from one atom in the emitted molecule to another atom in the same molecule to produce an environment conducive to thermally activated delayed fluorescence (TADF).
The current molecular design of TADF materials is focused on the combination of donor and acceptor units. But researchers at the Institute of Organic Photonics and Electronics Research (OPERA) at Kyushu University in Japan have proposed a method based on excited state intramolecular proton transfer (ESIPT) to achieve effective TADF without depending on the donor-receptor regimen described above.
When the emission molecule is excited by optical or electrical energy, it will spontaneously generate ESIPT.
Quantum chemical calculations conducted by researchers show that TADF is unlikely to occur before the transfer of hydrogen atoms. After hydrogen is transferred to different atoms in the same molecule, this forms a molecular structure capable of producing TADF. After the molecules emit light, the hydrogen is transferred back to its original atoms. Then the molecule is ready to start repeating the process.
ESIPT leads to the separation of the highest occupancy and the lowest unoccupied molecular orbital, resulting in nearly 60% of the luminous efficiency of TADF emission. The high external electroluminescence quantum efficiency of OLEDs using this emitter is as high as 14%, indicating that an efficient triplet harvesting effect can be achieved using ESIPT-based TADF materials.
The researchers said that this was the first demonstration of efficient TADF observed inside and outside the device.
The molecules used in this study were initially synthesized for the production of light-absorbing pigments.
This study can broaden and accelerate the development of various TADF materials for high performance OLEDs.
Has just begun to explore the advantages of the design strategy, but one of the particularly promising areas related to its stability. It is known that molecules similar to the molecules studied are highly resistant to degradation, so researchers hope that these molecules can help improve the life of OLEDs.
best selling led products:
Address: C&H Building, Wanda Industrial Park, Shiyan Town, Bao'an district, Shenzhen City, China
FAX : +86-755-33654451