According to the crystallographic data, the pendant (spacer) aryl rings are highly twisted from the carbazole bridge (D') due to congested steric interactions. The short distances between the donor and acceptor enable the through space interaction. By comparing with the emission at 492 nm from the exciplex between TPA and TRZ in toluene, the identical emission observed from Ph3TRZCzTPA and Ph2TRZCzTPA indicates that the CT emission in both comes from a through-space intramolecular TRZ-TPA CT excited state. No contribution from a throughbond, TRZ -weak D' CT pair was observed. Both Ph3TRZCzTPA and Ph2TRZCzTPA have the same small ΔEST of 20 meV in Zeonex matrix. However, Ph2TRZCzTPA has a faster kRISC than Ph3TRZCzTPA, which is ascribed to the more optimal tilted co-facial orientation of D and A forming the through-space CT state, which the authors contend is critical in controlling SOC and thus the RISC rate, as proposed by Kaji et al. The EQEmax values of the devices based on Ph3TRZCzTPA (20 wt% in 26DCzPPy) and Ph2TRZCzTPA (12 wt% in CBP) are 13.3% and 16.3%, respectively, which correlate with the relative RISC rates of the materials.