Bipolar Alq3-based complexes: Effect of hole-transporting substituent on the properties of Alq3-center

► Effects of substituent on the properties of Alq3-center were investigated. ► Energy transfer and electron transfer can transfer from substituent to Alq3-center. ► The thermodynamics and dynamics of electron transfer were studied. ► The mechanisms of PL and EL of Al(CzHQ)3 were studied and compared with each other.