講演情報
[15p-S4_201-1]Control of Spontaneous Orientation Polarization of Host Layers in Organic Light-Emitting Diodes
〇(DC)Gerardus Iswara Lestanto1, Shunta Kakumachi1, Youichi Tsuchiya1, Hajime Nakanotani2, Chin-Yiu Chan3, Chihaya Adachi1 (1.Kyushu Univ., 2.Hokkaido Univ., 3.City Univ. Hongkong)
キーワード：
Spontaneous Orientation Polarization、Organic Light-Emitting Diode
Spontaneous orientation polarization (SOP) arises from the alignment of a molecule's permanent dipole moment (PDM) during vacuum deposition, generating a giant surface potential (GSP) in organic films. SOP can significantly impact OLED performance, leading to effects such as charge accumulation or a higher turn-on voltage. Several strategies for SOP control hace been reported, including molecular substitution, conformational rigidity, and surface energy tuning. In this study, we explore the role of molecular structure in SOP by modifying a non-polar host molecule, DPCz, through cyano substition to obtain DPCzBN1-3. Despite similar photophysical properties, their SOP characteristics diverged significantly, DPCzBN3 showed a negative SOP, while DPCz remained relatively neutral. Codeposition with blue emitters, HDT-1, further amplified the negative SOP in the substititued hosts. OLEDs fabricated with these aterials as hosts confirmed the correlation between suppressed SOP and enhanced operational liftime, with DPCz-based devices exhibiting the longest lifetime due to the absence of SOP at the emission layer. These findings emphasize the critical role of SOP control in organic semiconductors.