# Highly Efficient Blue Host Compound Based on an Anthracene Moiety for OLEDs
## 1 Introduction  
Since [PERSON] et al. first introduced an efficient organic light-emitting diode (OLED) [1; 2; 3; 4], organic electroluminescent devices have garnered significant scientific and commercial attention due to their potential applications in full-color displays. Although OLED performance has significantly improved over the past few decades, further advancements are still needed in the research on blue emission. Due to their relatively lower performance compared to red and green OLEDs, improvements in performance for display and lighting purposes are necessary for blue OLEDs [5; 6; 7]. Previous studies on fluorescent blue-emitting materials have extensively reported on pyrene, chrysene, and anthracene derivatives. Among these, anthracene has been extensively studied as a core group for blue fluorescent materials due to its excellent photoluminescence, electroluminescence, and electrochemical properties [8; 9; 10]. Anthracene emits violet light in both solid and solution states, making it suitable as a core group for blue host materials [11; 12]. However, achieving amorphous films based on anthracene requires minimizing strong intermolecular forces such as hydrogen bonding or \(\pi\)-\(\pi\) stacking in the film state. To achieve this, bulky substituents are typically introduced to increase intermolecular distance and suppress intermolecular packing [13; 14; 15]. Another strategy for designing materials with amorphous characteristics is to synthesize asymmetric molecules to increase the number of conformers. Materials with many conformers may benefit the stability of amorphous films since they require high energy for crystallization [16; 17; 18; 19]. As a result, the asymmetric non-planar structure of anthracene molecules provides steric hindrance to densely packed molecular arrangements, eliminating crystallinity in the solid state and enabling the formation of stable thin films. The most well-known blue host materials based on anthracene are 9,10-di-2-naphthylthracene (ADN) and 2-tert-butyl-9,10-di-2-naphthylthracene (m-ADN), both of which have been commercially utilized. [PERSON] et al. reported anthracene host derivatives containing diarylsilyl groups, demonstrating high external quantum efficiency(EQE) (6.3%) and excellent Commission Internationale de L'Eclairage (CIE) coordinates (0.142, 0.149) [20]. Recently, [PERSON] et al. reported anthracene derivatives as host materials, incorporating dibenzofuran and naphthyl moieties as side groups, achieving an EQE of 8.1% and CIE coordinates of (0.123, 0.171). Furthermore, they demonstrated a low efficiency roll-off of 2.9% at 1000 nit [21]. Thus, research on host materials utilizing anthracene cores continues to be actively pursued. Previously, our group achieved a high EQE value of 9.25% and a current efficiency (CE) of 9.67 cd/A, along with a stable device lifetime with an LT\({}_{95}\) of 471 h, using the host material 9-(naphthalen-1-yl)-10-(naphthalen-2-yl)anthracene (\(\alpha\),\(\beta\)-ADN) [22]. In this study, we designed and synthesized the material 10-(4-(naphthalen-1-yl)phenyl)-9-(naphthalen-3-yl)anthracene (2-NaAn-1-PNa) to enhance thermal and amorphous properties by increasing molecular weight and introducing asymmetric characteristics compared to the previously used \(\alpha\),\(\beta\)-ADN host. We measured various properties, including optical, photophysical, and thermal properties. Furthermore, to evaluate the performance of 2-NaAn-1-PNa as a host, we fabricated doped devices using N\({}_{1}\),N\({}_{6}\)-bis(5-(tert-butyl)-2-methylphenyl)-N\({}_{1}\),N\({}_{6}\)-bis(2,4-dimethylphenyl)pyrene-1,6-diamine (3 Me-1 Bu-TPPDA) as the dopant and compared the device performance with our previous study.