Hybrid white organic light-emitting devices (OLEDs) are fabricated by employing non-doped emitting layers (EMLs), which are consisted of a blue thermally activated delayed fluorescent (TADF) emitter 9, 9-dimethyl-9, 10-dihydroacridine-diphenylsulfone (DMAC-DPS) and an ultrathin yellow iridium complex bis[2-(4-tertbutylphenyl)benzothiazolato-N,C 2 '] iridium (acetylacetonate) [(tbt) 2 Ir(acac)]. With thickness optimization of DMAC-DPS, a white OLED achieves maximum current efficiency, power efficiency, and external quantum efficiency of 34.9 cd/A, 29.2 lm/W, and 11.4 %, respectively, as well as warm white emission with relatively stable electroluminescence spectra. The results suggest that, bipolar charge carrier transport property and concentration independent property of DMAC-DPS, charge carrier trapping effect of the ultrathin (tbt) 2 Ir(acac), and balanced self-emission process and energy transfer process between DMAC-DPS and (tbt) 2 Ir(acac), contribute to high device performance.