Charge Recombination in Polaron Pairs: A Key Factor for Operational Stability of Blue-Phosphorescent Light-Emitting Devices
- 주제(키워드) electron transfer , molecular dynamics , OLED degradation , radical ion pairs , reorganization energy
- 주제(기타) Multidisciplinary Sciences
- 설명문(일반) [Odinokov, Alexey; Osipov, Alexey; Yakubovich, Alexander] Samsung Elect, Samsung R&D Inst Russia SRR, 12 Dvintsev St, Moscow 127018, Russia; [Oh, Juwon; Kang, Seongsoo; Kim, Dongho] Yonsei Univ, Spect Lab Funct Elect Syst, Seoul 03722, South Korea; [Oh, Juwon; Kang, Seongsoo; Kim, Dongho] Yonsei Univ, Dept Chem, Seoul 03722, South Korea; [Moon, Yu Kyung; You, Youngmin] Ewha Womans Univ, Div Chem Engn & Mat Sci, Seoul 03760, South Korea; [Ihn, Soo-Ghang; Lee, Hasup; Kim, Inkoo; Son, Won-Joon; Kim, Sangmo; Kravchuk, Dmitry; Kim, Jong Soo; Kim, Joonghyuk; Choi, Hyeonho; Kim, Sunghan] Samsung Elect, Samsung Adv Inst Technol SAIT, 130 Samsung Ro, Suwon 16678, South Korea; [Kim, Wook; Lee, Namheon] Samsung SDI Co Ltd, Dept Elect Mat, Suwon 16678, Gyeonggi Do, South Korea
- 관리정보기술 faculty
- 등재 SCOPUS
- 발행기관 WILEY-V C H VERLAG GMBH
- 발행년도 2020
- URI http://www.dcollection.net/handler/ewha/000000172367
- 본문언어 영어
- Published As https://dx.doi.org/10.1002/adts.202000028
초록/요약
Irreversible chemical reactions are responsible for limited operational lifetime of organic light-emitting devices (OLEDs). These reactions are triggered by highly reactive polaron pairs present in the emissive layer of OLEDs. Fast recombination of the polaron pairs is, therefore, crucial for slow degradation and high stability of OLED materials. Here, a study of the formation and annihilation of close polaron pairs in binary mixtures of wide bandgap hosts and a series of blue-phosphorescent Ir(III) complex dopants, including two novel compounds, is reported. OLED devices containing doped light-emitting layer are fabricated, and their operational lifetimes are estimated. Although inaccessible in solid films, charge recombination kinetics inside the polaron pairs is measured in liquid solutions using nanosecond laser flash photolysis. Multiscale computer simulations are applied to connect experimental results in different media and predict recombination rates in the device, with proper account taken of the inner- and outersphere reorganization in nonpolar materials. Predicted rates correlate with measured operational lifetimes, which demonstrates the key role of polaron pairs in the OLED degradation process. The developed methodology is useful for the rational design of novel OLED materials with higher efficiency and stability.
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