Enhancement of lifetime in blue triplet-triplet-fusion organic light-emitting diodes with fluorenyl amine- and triphenyl silane-based electron blocking layers

• Published in: Synthetic metals Vol. 304; p. 117571
• Main Authors: Park, Bubae, Lee, Hakjun, Kim, Taekyung
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2024
• Subjects: Blue fluorescent OLEDs; Electron blocking layer; Impedance spectroscopy; Lifetime; Transient electroluminescence; Electron blocking layer; Lifetime; Impedance spectroscopy; Blue fluorescent OLEDs; Transient electroluminescence
• ISSN: 0379-6779; 1879-3290
• DOI: 10.1016/j.synthmet.2024.117571

We report fluorenyl amine-based electron blocking layers (EBLs) N,9,9-triphenyl-N-(4′-(triphenylsilyl)-[1,1′-biphenyl]−4-yl)−9 H-fluoren-2-amine (P-pSi-DPFA), N,9,9-triphenyl-N-(3-(triphenylsilyl)phenyl)−9 H-fluoren-2-amine (P-mSi-DPFA), and N-([1,1′-biphenyl]−4-yl)−9,9-diphenyl-N-(3-(triphenylsilyl)phenyl)−9 H-fluoren-2-amine (BP-mSi-DPFA) that prevent intermolecular interactions with emissive layer (EML). Triplet-triplet fusion (TTF)-based organic light-emitting diodes (OLEDs) use anthracene derivatives as hosts, and due to the electron-rich nature of anthracene core, the recombination zone is predominantly formed at the EBL/EML interface. Therefore, it is important to control the intermolecular interaction between EBL and EML while also having an EBL with suitable hole transport characteristics and an appropriate highest occupied molecular orbital (HOMO) level. We developed TTF-based OLED achieving up to 1489 hours (LT50 at 500 cd/m2) using P-pSi-DPFA as the EBL, securing hole transport characteristics through a fluorenyl amine core, and preventing unwanted intermolecular interactions with the EML by substituting triphenyl silane into the amine core. •Three newly synthesized EBL materials extended OLED device lifetime significantly.•Experimental and theoretical analyses support EBL materials' effectiveness.•P-pSi-DPFA device achieved an impressive 1489-hour lifetime at 500 cd/m².