High Performance Deep Blue Organic Room Temperature Phosphorescence: 4.64 s Ultra-Long Lifetime and 60.4% Quantum Efficiency Balanced by Simple Phosphor Heteroatom Modulation.

In the organic room-temperature phosphorescence (RTP) field, the high performance deep blue emission with high color purity remains a challenge due to low stability under high energy gap constraints and the trade-off between lifetime and quantum efficiency. In this study, high performances deep blue RTP materials are successfully fabricated by doping three pinacol boronic ester (BPin) derivatives into a polyvinyl alcohol (PVA) matrix for the first time, with CIE coordinates (0.149, 0.061)/ (0.147,0.069)/ (0.145,0.076) for carbazole (CZBPin), dibenzofuran (DBFBPin) and dibenzothiophene (DBTBPin) based BPin respectively. By simple heteroatom modulation in these three phosphor molecules, altralong lifetime up to 4.64 s and a phosphorescence quantum yield of 60.4% is balanced. Moreover, even at an extremely low doping concentration (0.001 wt.%), the material maintained an ultra-long phosphorescence lifetime of 1.91 s, which make the future practical applications cost-effective. Further theoretical calculations and Raman spectroscopy measurement prove that the strong hydrogen bonds between the guest molecules and PVA chains effectively restricted molecular vibrations and motions, thereby promoting phosphorescence performances. Finally, solar energy activated emission, information encryption, and multicolor displays through triplet-to-singlet Förster resonance energy transfer (TSFRET) are demonstrated for future potential applications.