Achieving highly efficient near-ultraviolet emitters via optimizing molecular configuration by the intramolecular-locked donor and acceptor

•Near-ultraviolet fluorescence with atypical planar structures.•Atypical planar structure can promote the emission blue-shift.•The enhancing rigidity of molecule can obtain high PLQY.•TPhPO moiety can reduce the LUMO energy level to bring near-ultraviolet emission.•Doped device of DPhPO-Ad achieved the highest maximum ηext of 4.58%.