Di‐Channel Polyfluorene Containing Spiro‐Bridged Oxadiazole Branches

Abstract

Summary: A p–n di‐channel copolymer based on polyfluorene (PF) has been designed and prepared. Branches containing oxadiazole units are attached to the PF backbone through the spiro‐structure and act as channels to improve the electron affinity; these branches form a steric ‘di‐channel’ framework with the polymer backbone. The polymer possesses excellent thermal stability. The lowest unoccupied molecular orbital energy level of the polymer is significantly altered in comparison with poly(9,9‐dioctylfluorene‐2,7‐diyl).Schematic of the di‐channel polyfluorene synthesized here and the mechanism of energy transfer through the structure.magnified imageSchematic of the di‐channel polyfluorene synthesized here and the mechanism of energy transfer through the structure.

Effective adjustment of the optoelectronic properties of organic conjugated materials by synthesizing p-n diblock molecules

“…In the solid state, chelating polymers show almost complete energy transfer from the host fluorene segments to the guest Ir complexes when the feed ratio is only 2 mol%. The HOMO (LUMO) energy level of PF is −5.8 eV (−2.12) eV [37]. The HOMO energy levels of π-conjugated chelating polymers are estimated to be about −5.76 to −5.80 eV, and the LUMO energy levels are about −2.19 to −2.25 eV.…”

“…of OXD branches onto the PF backbone through the spiro-bridge, and the E a is significantly raised[37]. Huang et al also find that hyperbranched OXDcontaining p-n diblock PFs (e.g., 31) exhibit very stable blue light emission even after being annealed at elevated temperatures in nitrogen or air (Figure 15)[38−40].…”

Progress in long wavelength emission in fluorene-based electroluminescent blue materials

“…Huang et al [18,19] introduced the noncoplanar structure-spirofluorene into PF ( Figure 6), resulting in great enhancement of T g of polymer, restraint of its tendency to crystallize, weakening of the formation of aggregation and excimer-related species, and improvement of the photostability, which pioneered an effective tool to resolve the troublesome long wavelength emission in FEBMs. Huang et al [20] applied the molecular design method of p-n blocks to spirofluorene related materials by introducing electron deficient oxadiazole branches into spirofluorene polymer. They synthesized a p-n di-channel copolymer based on PF ( Figure 7).…”

Synthesis of Dendritic Oligo‐Spiro(fluorene‐9,9′‐xanthene) Derivatives with Carbazole and Fluorene Pendants and their Thermal, Optical, and Electroluminescent Properties

“…[20,33] TSF-F exhibits a broad oxidation wave with one peak value at 1.93 V and another, poorly resolved, shoulder peak around 1.50 V. The two peaks correspond to the oxidations of its fluorene pendants and the backbone, respectively. Furthermore, TSF-F has a comparatively higher onset potential at 1.20 V. According to the literature, [34,35] Calculated from the onset position of the absorption band in the thin film state. the following equation:…”