## 2 Materials and Methods
### Instrumentation  
\({}^{1}\)H and \({}^{13}\)C NMR analyses were performed with a JEON JNM-ECP FT-NMR spectrometer (Peabody, MA, USA) operating at 500 MHz. The UV-Vis absorbance property was analyzed with a Lambda 1050 ultraviolet visible (UV-VIS) spectrophotometer (Perkin Elmer, Waltham, MA, USA). The energy of the band gap (Eg) was obtained from the onset wavelength of the UV-Vis absorbance spectra. Photoluminescence (PL) spectra were measured with an HR800 spectrofluorometer (Horiba Jobin Yvon, Paris, France). Mass spectrometry analysis was carried out with a Xevo TQ-S spectrometer (Waters,Milford, MA, USA). An elemental analysis (EA) was performed with a ThermoFisher (Flash 2000) elemental analyzer (Loughborough, England). Thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) were recorded with a PerkinElmer DSC 4000 and TGA 8000 system (Melville, NY, USA) under a nitrogen atmosphere with a heating rate of 10 \({}^{\circ}\)C/min. The triplet energy level (ET) was estimated from the onset wavelength of the emission spectra at 77 K in toluene. The HOMO (highest occupied molecular orbital) value was determined by a AC-2 method with a photoelectron spectrometer (RIKEN, Saitama, Japan). The LUMO (lowest unoccupied molecular orbital) energy was calculated by adding the band gap energy to the obtained HOMO energy. OLED devices were constructed with a thermal evaporating system under a pressure of \(5\times 10^{-7}\) torr (Sunicel plus, Seoul, Korea). Current density-voltage-luminescence (_J-V-L_) performances were observed by an OLED _I-V-L_ test system (Polarmix M6100, Suwon, Korea). The electroluminescence (EL) spectra were recorded with a spectroradiometer (Konica Minolta CS-2000, Tokyo, Japan).  
Synthesis of N\({}^{1}\)-(9,9-diphenyl-9H-fluoren-2-yl)-N\({}^{4}\),N\({}^{4}\)-diphenylbenzene-1,4-diamine (3)  
A mixture of 9,9-diphenyl-9H-fluoren-2-amine (1, 1.0 g, 2.99 mmol), 4-iodo-_N_,_N_-diphenylaniline (2, 1.22 g, 3.29 mmol), palladium (II) acetate (Pd(OAc)\({}_{2}\), 0.1 g, 0.45 mmol), sodium _tert_-butoxide (NaOfBu, 0.43 g, 4.49 mmol), 10% tri-_tert_-butylphosphine in toluene (_t_Bu3P, 0.20 mL, 0.89 mmol) and anhydrous toluene (80 mL) was added into a two-neck round-bottom flask that was equipped with a condenser. The above mixture was subjected to a vacuum, and then a nitrogen atmosphere was provided. The mixture was refluxed at 110 \({}^{\circ}\)C for 10 h while being stirred with a magnetic bar. After the completion of the reaction, a crude mixture was made up by using dichloromethane (250 mL) and deionized water (125 mL) three times. The organic layer was collected and dried over anhydrous magnesium sulphate. After filtration, the crude mixture was evaporated by using a rotary evaporator. The target molecule (3) was achieved via silica column chromatography with an _n_-hexane:dichloromethane (2:1) solvent system (Scheme 1).  
Characterization of N\({}^{1}\)-(9,9-diphenyl-9H-fluoren-2-yl)-N\({}^{4}\),N\({}^{4}\)-diphenylbenzene-1,4-diamine (3)  
Yield: 91%; yellow solid; \({}^{1}\)H NMR (500 MHz, CDCl\({}_{3}\)) 8 9.47-9.49 (d, \(J\) = 8.0 Hz, 1H), 8.17-8.19 (d, \(J\) = 8.0 Hz, 1H), 8.09-8.11 (m, 2H), 7.95-8.02 (m, 2H), 7.75-7.89 (m, 2H), 7.59-7.60 (d, \(J\) = 8.0 Hz, 4H),7.43-7.44 (d, \(J\) = 7.5 Hz, 3H), 7.34-7.36 (d, \(J\) = 8.5 Hz, 4H), 7.17-7.19 (d, \(J\) = 8.5 Hz, 3H), 6.99-7.02 (t, \(J\) = 7.5 Hz, 3H), 6.90-6.93 (t, \(J\) = 7.5 Hz, 3H), and 6.39-6.41 (d, \(J\) = 8.5 Hz, 3H).