In the realm of RTP OLEDs, several significant challenges persist, hindering their advancement. These obstacles include the low PLQY in amorphous films, inferior EQE of the devices, unstable electroluminescence spectra and limited molecular design lithium fluoride (LiF) (1 nm)/ aluminum (Al) (100 nm) (Fig. ). Detailed device data are shown in Fig. , c&d, and in Table . The fabricated devices exhibited sky-blue electroluminescence (EL) with a peak wavelength of 492 nm with the CIE color coordinates of (0.19, 0.36) and (0.18, 0.36), respectively. These values were slightly red-shifted compared with the PL spectra in doped films. Notably, the EL spectra remained remarkably stable at different voltages, owing to the small ΔEST and nearcomplete overlap of fluorescence and phosphorescence spectra (Supplementary Fig. ). This achievement overcomes the limitations typically associated with conventional RTP devices. The devices based on TCBPSF achieved higher maximum current efficiency (CE) of 59. Tn, n = 1, 2), and SOCME (S0, Tn, n = 1, 2) of TCBPSF and HCBPSF. h-i, The photophysical processes of TCBPSF and HCBPSF in PMMA matrix, respectively. UC is a triplet-triplet up-conversion process.