in a host-free configuration and showed a much-improved EQEmax of 10.1% compared to the OLED based on TZ (1.09%). The photophysics and electrochemical characteristics of the aforementioned materials are summarized in Table and representative device performance metrics are summarized in Table . reported two related green TADF emitters mCBPTRZ- Dimerization is expected to enhance the overlap between frontier molecular orbitals, which leads to an increase of the oscillator strength, thus resulting in higher FPL, but at the expense of a red-shifted emission along with a larger ΔEST. The OLED using mCBPTRZ-1 (λEL: 503 nm; CIE = (0.23, 0.52) emits in the green with an EQEmax of 20.8% while the device using mCBPTRZ-2 (λEL: 521 nm; CIE = (0.31, 0.59)) that contains the more electron-rich 3,6-ditert-butylcarbazole shows a red-shifted emission and a significantly lower EQEmax of 9.3% despite of the high FPL of the emitter. The low device efficiency was rationalized by the authors as due to the weak exciton conversion efficiency of 41% in the mCBPTRZ-2-based device compared to 90% in the mCBPTRZ-1-based device. However, this explanation does not seem plausible given their similar molecular structures and photophysics. Reproduced with permission. Copyright © 2017, Elsevier.