Electro luminescent device comprising fluorene compounds

An electro-luminescence device for emitting light within a visible light wavelength, comprising:

• an anode layer;
• a hole transport layer
• an electron transport layer;
• and
• a cathode layer;
• wherein the anode layer, the hole transport layer, the electron transport layer, and the cathode layer are disposed in the above order;
• and the hole transport layer includes a compound having the formula:
• in which
• each of R1-R4, R5-R8, and R5′-R8′, independently, is H, halogen, CN, NO2, amino, alkylamino, arylamino, dialkylamino, diarylamino, hydroxyl, alkoxyl, aryloxyl, heteroaryloxyl, mercapto, alkylthio, arylthio, heteroarylthio, alkyl, aryl, heteroaryl, or heterocyclyl;
• each of A and B, independently, is phenyl, naphthyl, or phenanthyl;
• and
• each of R9 and R10, independently, is aryl, heteroaryl, aryloxyl, or heteroaryloxyl.