## Materials and Methods
### Instrumentation  
\({}^{1}\)H and \({}^{13}\)C NMR spectra were recorded using a JEON JNM-ECP FT-NMR spectrometer (Peabody, MA, USA) operating at 500 MHz. Absorbance spectra were obtained using a SINCO S-4100 ultraviolet visible (UV-VIS) spectrophotometer (SINCO, Seoul, Korea). The energy of the band gap (E\({}_{\rm g}\)) was estimated from the onset wavelength of the UV-VIS absorbance spectra. Photoluminescence (PL) spectra were recorded using a HR800 spectrofluorimeter (Horiba Jobin Yvon, Paris, France). The triplet energy level (E\({}_{\rm T}\)) was determined from the onset wavelength of the emission spectra at 77 K in tetrahydrofuran (THF). The HOMO (highest occupied molecular orbital) level was calculated by the AC-2 method using a photoelectron spectrometer (RIKEN, Saitama, Japan). The LUMO (lowest unoccupied molecular orbital) level was estimated by adding the band gap energy to the obtained HOMO energy. OLED devices were fabricated by a thermal evaporating system (5 \(\times\) 10\({}^{-7}\) torr pressure) (Sunicel plus, Seoul, Korea). Current density-voltage-luminescence (J-V-L) efficiencies were recorded by an OLED I-V-L test system (Polarmix M6100, Suwon, Korea). The electroluminescence (EL) spectra analysis was obtained by using a spectroradiometer (Konica Minolta CS-2000, Tokyo, Japan). Thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) were organized by using SDT Q600 V20.9 Build 20 and DSC Q200 V24.9 Build 121 (TA Instruments, New Castle, DE, USA) instruments with a heating rate of 10 \({}^{\circ}\)C/min under an inert atmosphere. Mass spectrometry analysis was carried out using a Xevo TQ-S spectrometer (Waters, Milford, MA, USA). Elemental analysis (EA) was measured by an IT/flash/2000 elemental analyser (Thermo Fisher Scientific, Loughborough, UK).  
Synthesis of 4-(9,9-Diphenylacridin-10(9H)-yl)-N-(4-(9,9-diphenylacridin-10(9H)-yl)phenyl)-N-phenylaniline (TPA-1A)  
A mixture of 4-bromo-N-(4-bromophenyl)N-phenylaniline (TPA, 2 g, 4.96 mmol), 4-(9,9-diphenylacridin-10(9H)-yl)-N-(4-(9,9-diphenylacridin-10(9H)-yl)phenyl)-N-phenylaniline (1A, 3.47 g, 10.40 mmol), Pd(OAc)\({}_{2}\) (0.03 g, 0.15 mmol), sodium tert-butoxide (1.81 g, 18.80 mmol), 10% tri-tert-butylphosphine in toluene (0.70 mL, 3.5 mmol) and 100 mL of anhydrous toluene were added in a two-neck 150 mL round bottom flask equipped with condenser. The mixture was then stirred at 110 \({}^{\circ}\)C for 10 h under a nitrogen atmosphere. The residues were extracted with dichloromethane (3 \(\times\) 30 mL) and deionized water (60 mL). The organic layer was collected, dried over anhydrous sodium sulphate and concentrated through a rotary evaporator. Finally, the crude material was separated using a silica column with an \(n\)-hexane: dichloromethane (5:1 to 1:1) gradient-based mobile phase to achieve the pure TPA-1A target molecule. Synthesize route of TPA-1A is illustrated in Scheme 1.  
CDCl\({}_{3}\)) & 7.32-7.35 (t, \(J\) = 10 Hz, 1H), 8.22-8.26 (m, 9H), 7.09-7.12 (m, 2H), 6.97-6.98 (m, 4H), 6.92-6.93 (d, \(J\) = 8.5 Hz, 2H), 6.87-6.88 (d, \(J\) = 8.5 Hz, 4H), 6.55-6.57 (d, \(J\) = 8 Hz, 2H) ; \({}^{13}\)C NMR (500 MHz, CDCl\({}_{3}\)) & 147.26, 146.44, 142.40, 130.47, 130.00, 129.90, 129.72, 127.67, 126.93, 126.33, 125.28, 116.12, 114.13; MS (APCI) \(m/z\): 907.83 for C\({}_{68}\)H\({}_{49}\)N\({}_{3}\) [(M + H)\({}^{+}\)]. Anal. Calcd for C\({}_{68}\)H\({}_{49}\)N\({}_{3}\) (%): C, 89.93; H, 5.44; N, 4.63. Found: C, 89.86; H, 5.40; N, 4.71.