In the first part, TADF emitters based on N-heterocyclic donors and boron-containing acceptors were designed and synthesized. Photophysical studies revealed that blue emission was accessed through the variation of the N-heterocyclic donors. Secondly, a series of TADF emitters derived from the indolocarbazole donors and di-phenyltriazine acceptors were evaluated. OLED with the EQE of over 22.1% and sky-blue emission at 483 nm was obtained. Lastly, deep blue TADF emission was realized by introducing electron-withdrawing groups to the [2.2]paracyclophane-derived donor unit. For further decreasing the ΔEST to harvest more efficient TADF molecules, through-space donor dimers and the corresponding emitters were also synthesized, yielding blue TADF emission.