Prof. Soo Young Park Profile

Prof. Soo Young Park

Associate Professor at Seoul National Univ

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Publications (3)

Proceedings Article | 10 September 2019 Presentation

Shifting TADF of phenyl-s-triazine derivatives to deep-blue: the approaches increasing triplet and singlet excited state energies (Conference Presentation)

Illia Serdiuk, Chi Hyun Ryoo, Karol Kozakiewicz, Beata Liberek, Ji Eon Kwon, Soo Young Park

Proc. SPIE. 11093, Organic and Hybrid Light Emitting Materials and Devices XXIII

KEYWORDS: Polishing, Organic light emitting diodes, Luminescence, Optoelectronic devices, Excitons

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During the last few years, the phenomenon of thermally activated delayed fluorescence (TADF) finds more and more applications in numerous fields of technology, especially in organic light emitting diodes (OLED) giving rise to variously shaped and flexible optoelectronic devices and displays. Further development of products using OLED technology requires emitters exhibiting deep-blue TADF with relatively short emission lifetimes and high chemical stability. The state-of-the-art pure organic TADF emitters comprise donor and acceptor fragments separated spatially. This enables very small gap between the lowest singlet and triplet excited states of charge-transfer (CT) character. However, as these states differ only by multiplicity, the transition between them is forbidden by the selection rules. According to the current understanding of TADF mechanism, the efficient conversion of nonradiative triplet excitons to the emissive singlet ones occurs when a locally excited triplet state (3LE) is energetically close to the ¹CT and ³CT states. The photophysical principles described above work very well for design of efficient yellow, green, and sky-blue TADF materials. To achieve deep-blue TADF, the emitter should comprise highly energetic CT and ³LE states, which is a challenging requirement. To face this problem we investigated two approaches of increasing excited states’ energies: (i) reduction of conjugation of the acceptor fragment by its deplanarization and (ii) introduction of electron-releasing substituents in the acceptor fragment. 2-Phenyl-s-triazine and 9,10- dihydro-9,9-dimethylacridine were selected as acceptor and donors fragments, respectively. Our results show that both approaches efficiently increase energies of the CT and acceptor ³LE states, maintaining the rate constant of reverse intersystem crossing in the 10⁵–10⁶ s^–1 range. This presentation will focus on details of the above mentioned investigations including characteristics of the OLED devices.

Proceedings Article | 14 July 2003 Paper

Molecular photonics materials with excited-state intramolecular proton transfer (ESIPT) activity

Soo Young Park, Sehoon Kim

Proc. SPIE. 4991, Organic Photonic Materials and Devices V

KEYWORDS: Polymers, Luminescence, Hydrogen, Electroluminescence, Chromophores, Solids, Absorbance, Picosecond phenomena, Dendrimers, Absorption

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Proceedings Article | 14 July 2003 Paper

Triphenyl amine-cored multibranched organic glasses for photonic applications

Soo Young Park, Hye Jeong Lee, Jiwon Sohn, Jaehoon Hwang, Haeyoung Choi, Myoungsik Cha

Proc. SPIE. 4991, Organic Photonic Materials and Devices V

KEYWORDS: Diffraction, Optical properties, Glasses, Luminescence, Nitrogen, Optical storage, Nonlinear optical materials, Nonlinear optical glasses, Photonic glasses, Absorption

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