Crystalization-enhanced Stability by Effectively Suppressing Pho-tooxidation Defect for Lasing Emission and Electroluminescent Device

Abstract

Effectively protection against photooxidation of wide bandgap semiconductors remains a challenge that become the bottleneck on the road to commercialization. Herein, we demonstrated the crystallization effects of fluorene-based blue emitters on long-wavelength green band (g-band) defect with the well-defined organic micro/nanocrystals obtained via the self-assembly of surfactant-assisted reprecipitation methods. For the key molecule model 2,2'-bi(9,9-dipropyl)fluorene (DDC3F), the self-assembled nanorods film ex-hibits an ultrastable spectral stability without the presence of g-band emission (530 nm), and even main-tains the deep-blue emission under ultraviolet exposure (~ 3 h). In contrast, the spin-coated amorphous film shows a poor color purity with a green-index of ~ 4. Our results offer a robust evidence on the princi-ple in aggregate-enhanced stability, which is severely ignored by the general application of amorphously glassy molecules in OLED devices. In addition, the single nanorod as Fabry-Pérot (FP) optical resonator exhibits size-dependent dual wavelength lasing at 392 nm (threshold: 102 mW/cm2) and 412 nm (threshold: 216 mW/cm2), and generates the deep-blue electroluminescence in solution-processing OLED devices. The supramolecular self-assembled micro/nanocrystals strategy provides a potential platform to maintain ultrastable color purity in wide-bandgap optoelectronic device.