To seek effective thermally activated delayed fluorescence (TADF) molecules, we have designed compounds 1-4 by introducing substituents on the para-position of boron atom of blue TADF molecule (DABNA-1). The results indicate that 1-4 not only retain the blue emission from 454 to 466 nm, but also possess larger oscillator strength. Besides, the fluorescence radiative rates (k(r)) of 1-4 are higher than that of DABNA-1. The singlet-triplet energy splitting (Delta E-ST) values of designed compounds are smaller than that of DABNA-1. Taking both Delta E-ST and kr into account, designed compounds show better TADF performances, indicating their potential as TADF materials. (C) 2018 Elsevier B.V. All rights reserved.