To gain a deeper insight into the fundamental basis of the intrinsic RTP exhibited by the dendrimer, quantum-chemical calculations were conducted to investigate two crucial photophysical processes: (1) the enhancement of ISC spin-flipping processes from the S1 to the nth triplet state (Tn) (kISC), and (2) the facilitation of the phosphorescent decay rate from the T1 to the S0 (kP). The ISC process was evaluated based on equation (1) .