Long-Lived\nRoom-Temperature Phosphorescence from Silica\nNanoparticles with In Situ Generated Carbonaceous Defects for Blue\nOrganic Light-Emitting Diodes

In\nthis study, in situ formed silica nanoparticles (SNPs) emitting\nsecond-level phosphorescence at room temperature without a phosphorescent\ndopant have been achieved for the first time. This phosphorescence\nis achieved through the simple in situ formation of carbonaceous defects\n(CDs) within the SNPs, followed by passivation of the CDs by a robust\nsilica matrix. The CD in the SNPs, termed CD@SNPs, are synthesized\nby cross-linking tetraethyl orthosilicate (TEOS) and (3-aminopropyl)triethoxysilane\n(APTES), and these cross-linked components create a porous structure\nwithin the silica matrix. Upon calcination, the carbon-related structures\nwithin the pores deform, leading to the formation of CDs. Confined\nwithin a robust silica matrix, the molecular motion of the CD is restricted,\nfacilitating the generation of a stable triplet state and suppressing\nnonradiative decay. Moreover, the robust silica matrix passivates\nthe CD confined in the SNPs at a nanoscale. These comprehensive effects\nenable prolonged phosphorescence emission from the SNPs. In addition,\nthese phosphorescence-emitting SNPs have been applied as dopants in\nthe emissive layer of organic light-emitting diodes to realize blue\nlight emission. This feature suggests the possibility of utilizing\nluminescent SNPs as light emitters in display technologies.