O‐B‐O Positional Isomerism and Matrix Synergy in Arylboronic Ester‐Modified Naphthalene: A Strategic Approach for Enhanced Organic Phosphorescence and Time‐Resolved Multilevel Information Encryption

Organic room‐temperature phosphorescence (RTP) materials have attracted widespread attention for their potential in both fundamental research and advanced technologies, owing to their unique long‐lived luminescence characteristics. However, their development is hampered by issues such as low triplet exciton generation efficiency, oxygen quenching, and nonradiative decay in organic molecules. In this study, we propose an effective strategy to modulate polymer‐confined arylboronate RTP via positional isomerization. Two naphthyl isomers with O‐B‐O units, 2‐phenylnaphtho[2,3‐d][1,3,2]dioxaborole (2,3‐NPB) and 2‐phenylnaphtho[1,8‐de][1,3,2]dioxaborinine (1,8‐NPB), were synthesized. Interestingly, despite their identical chemical compositions, they display distinctly different performances in poly(vinyl alcohol) (PVA) films: 2,3‐NPB@PVA exhibits a phosphorescence lifetime of 867 ms and a photoluminescence quantum yield of 38.5%, whereas 1,8‐NPB@PVA delivers corresponding values of 765 ms and 12.2%. Experiments and calculations confirm that O‐B‐O positional isomerism alters aromaticity, geometry, and electrostatic potentials, thus modulating the competition between triplet exciton evolution and nonradiative decay. The good film‐forming ability, flexibility, and processability of PVA confer deformation tolerance, indicating potential in flexible anti‐counterfeiting and secure information storage. This work not only achieves precise triplet‐state control in purely organic boron‐based phosphors, but also elucidates structure‐property relationship (O‐B‐O positional isomerism‐microstructure‐triplet evolution‐matrix synergy), offering a concise design route for high‐performance RTP materials.