Presentation Information
[11a-A33-1]Investigating Exciton Diffusion and Harvesting Dynamics in Lanthanide-Based OLEDs
〇(PC)Shiori Miyazaki1,2, Yunzhou Deng1, Kenichi Goushi2, Kiyoshi Miyata2, Chihaya Adachi2, Ken Onda2, Akshay Rao1 (1.University of Cambridge, 2.Kyushu Univ.)
Keywords:
energy transfer,lanthanide,LED
Trivalent lanthanide (Ln3+) complexes are attractive emitters for organic light-emitting diodes (OLEDs) owing to their narrowband emission arising from 4f–4f electronic transitions. Although highly efficient ligand-to-metal sensitization enables high photoluminescence quantum yields (PLQYs), the electroluminescence (EL) efficiencies of Ln3+-based OLEDs remain lower than expected. Understanding exciton dynamics under electrical operation is therefore essential for improving device performance.Here, we investigate Eu3+-complex-based OLEDs employing [Eu(hfa)3(TPPO)2] as the emissive guest and 2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine (mT2T) as the host material. Previous studies have demonstrated highly efficient host-to-Eu3+ energy transfer and high PLQYs in this system under optical excitation. To directly probe exciton dynamics under device operation, we combine time-resolved electroluminescence (TREL) and electrically pumped transient absorption (ETA) spectroscopy.The transient measurements reveal microsecond-scale triplet exciton migration and harvesting dynamics despite the intrinsically fast nanosecond host-to-Eu energy-transfer process. These observations indicate that EL formation is governed not only by intrinsic energy-transfer kinetics but also by exciton transport within the host matrix prior to capture by localized Eu3+ emissive centres. This work highlights the importance of operando spectroscopic approaches for elucidating exciton dynamics in lanthanide-based OLEDs and provides new insight into the role of exciton transport in determining device performance.