To improve the efficiency of the devices, we next explored the fabrication of TADFsensitized-fluorescence, or hyperfluorescence (HF), devices (Figure ). Here, 4CzIPN was selected as the TADF assistant dopant because of its high ΦPL, short τd in mCP, and a strong spectral overlap between the absorption spectra of these four emitters and the PL spectrum of 4CzIPN in toluene (Figure ). The optimized ratio of emitters/4CzIPN/ mCP was established in the literature to be 3: 32: 65. The device performance is shown in Figure -e, and the data are summarized in Table . As shown in Figure , the EQEs of the HF devices with all four compounds have been greatly improved compared to the previous set of devices. The HF devices with 2DPACzBP showed an enhanced EQEmax of 20.0% at λEL= 605 nm (Figure ), much higher than 7.8% in the non-HF devices. However, a noticeable blueshift in the EL spectra was observed, moving from λEL = 640 nm (no-HF devices) to λEL= 605 nm in HF devices, which we attributed to the lower doping concertation of emitter in the EML.