Theoretical studies on mechanism of thermally activated delayed fluorescence and desing for novel emitting molecules to develop next-generation organic light-emitting diodes

2014 Fiscal Year Final Research Report

• Project/Area Number: 24550210
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Functional materials/Devices
• Research Institution: Kyoto University
• Principal Investigator: SATO Tohru 京都大学, 工学(系)研究科(研究院), 准教授 (70303865)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 有機EL / 振電相互作用 / 熱活性型遅延蛍光 / フラーレン / ポルフィリン

Outline of Final Research Achievements

Thermally activated delayed fluorescence (TADF) has been expected as a next generation emitting-mechanism of organic light-emitting diodes. Donor-acceptor systems have been reported as TADF molecules. However, it is known that non donor-acceptor systems such as C60 and Sn porphins exhibit TADF. We theoretically investigated the emitting mechanism of the non-donor-acceptor molecules to establish a novel design principle for emitting molecules. We found that the selection rules of electric dipole transition and spin-orbit coupling play crucial roles in these systems. In this mechanism, reverse intersystem crossing occurs via triplet excited state higher than T1. We call this TADF symmetry-controlled TADF. Furthermore, the energy gap can be negative. This electronic structure is called inverted singlet-triplet (iST) structure. We obtain a design principle for these novel mechanism. Based on the design principle, we succeeded in designing novel emitting molecules with the iST structure.

Free Research Field

理論化学