###### Abstract  
New blue-light-emitting materials, 2,7-Bis-[1,1',3',1'']perphenyl-spiro-fluorene[3,4] naphthalene (TP-AFF-TP) and spiro-fluorene[3,4]-5-terphenylingphthalene (TP-ASF) were synthesized based on a fused core with anthracene and spirofluorene. The photoluminescence (PL) maximum values of TP-AFF-TP and TP-ASF in film states exhibited 477 nm and 467 nm within the blue region, respectively. Degradation temperature (T\({}_{\text{d}}\)) values for TP-AFF-TP and TP-ASF were very high at 481 \({}^{\circ}\)C and 407 \({}^{\circ}\)C, respectively. TP-AFF-TP and TP-ASF exhibited power efficiencies (PE) of 1.03 lm/W and 2.39 lm/W, respectively, along with luminance efficiencies (LE) of 2.55 cd/A and 5.17 cd/A, respectively, in nondoped organic light-emitting diode (OLED) devices in which the newly synthesized compounds were employed as emissive layers. The achieved CIE values were (0.25, 0.45) for TP-AFF-TP and (0.17, 0.31) for TP-ASF. Furthermore, when TP-ASF was utilized as one of the emissive materials in solution-processed white OLED devices, the resultant device showcased a notably high LE of 3.13 cd/A, a PE of 2.69 lm/W, and a white CIE value of (0.30, 0.34).  
bin-light-emitting materials; fused core moiety; anthracene; spirofluorene groups +
Footnote †: journal: Applied  
development of luminophores composed of dual-core and triple-core structures, and further progress has been made by employing fused core combinations [14; 15]. Recently, there have also been many reports about multiple resonance emitters and hyperfluorescence blue OLEDs [16; 17].  
Traditionally, vapor deposition has been the mainstream method for OLED device commercialization due to its guaranteed high performance. However, the solution process of OLED devices has been greatly focused because of the simple process and particularly low-cost effect, although solution processing still needs to develop the related device property [18; 19; 20; 21]. While the utilization of polymer-based light-emitting diodes (PLEDs) is a feasible avenue for the solution processing of OLEDs, challenges arise in terms of effectively purifying PLED materials and regulating molecular weight during large-scale production. On the contrary, solutions based on small molecules for the procedure need to demonstrate harmony between remarkable dissolvability and increased radiation effectiveness attributes.  
Based on this information, we designed new sky-blue-emitting materials, including anthracene and spirofluorene core, for suitable solution processes. First, we prepared the main core with a fused structure of anthracene and spirofluorene for good luminance efficiency (LE). Second, to prevent \(\pi\)-\(\pi\) stacking interactions, a side group was introduced into the core structure. Also, in the case of the two fused chromophores, it is confirmed that the EL performance is improved upon the side group position of anthracene or spirofluorene. Lastly, highly twisted compounds provide good solubility and they can be applicable to the solution process. The newly synthesized blue-emitting materials consist of 2,7-Bis-[1,1',3',1']perphenyl-spiro-fluorene[3,4] naphthalene (TP-AFF-TP) and fluorene[3,4]-5-terphenyl naphthalene (TP-ASF) (Figure 1). The synthesized materials were analyzed thermal and electronic characteristics through techniques such as thermogravimetric analysis (TGA), ultraviolet-visible light absorption spectroscopy (UV-Vis), and photoluminescence (PL) spectroscopy. Using these synthesized materials, multilayered electroluminescent (EL) devices were manufactured. These materials were utilized not only as emitters without doping but also as dopants in white OLEDs based on solution processing [22].