Monodisperse Six-Armed Triazatruxenes:  Microwave-Enhanced Synthesis and Highly Efficient Pure-Deep-Blue Electroluminescence

Abstract

For large-area full-color displays, high-performance bluelight-emitting diodes (LEDs) are highly desired and yet still remain a materials challenge. 1 Fluorene-based oligomers and polymers (PFs) have proven so far the dominant candidates for their high quantum yields and good thermal stabilities; 2 however, a prime problem encountered is the formation of aggregates, excimers, or keto defects, which leads to reduced efficiency and additional green emission. 3 Efforts by us and others on incorporation of sterically hindered units to PFs and constructing cross-linked or hyperbranched PFs have been investigated to address the above problem. 4 The resulting materials are less prone to aggregation in the solid state due to their hindered structures and emit purer blue light, while the device efficiencies have not been much improved. Other efforts on introducing arylamine units (such as carbazole, triphenylamine, or triazole) into PFs have rendered promising results in improving device efficiency as well as color stability, 5 but the emissions are mainly light blue or sky blue, not saturated pure blue. 5c-e Although deep-blue emission with improved color stability and efficiency has also been demonstrated by some of them, the device performance was found dependent on molecular weights (M w ), which are not readily controllable for polymers. 5b,f

Melanin‐Inspired Organic Electronics: Electroluminescence in Asymmetric Triazatruxenes

“…One of the main applications of symmetrical TATs reported in the literature is as the organic emitting layer in OLED devices, [12,21] whereas no applications have been reported for the asymmetric isomers. In all the reported cases, to improve the quite low photo-and electroluminescence, the symmetrical TAT core has been functionalized with polycarbazole or polyfluorene arms to generate more efficient star-shaped structures.…”

“…Some TATs can behave as twophoton absorption chromophores, [8] can generate electroactive discotic liquid crystals, [9] and have been tested in organic fieldeffect transistors (OFETs). [10] Reported applications of TATs include the development of bulk heterojunction solar cells, [11] organic light-emitting diodes (OLEDs), [12] and sensing devices. [13] In this paper we report: the synthesis, separation, and comparative characterization of eumelanin-inspired symmetric and asymmetric TATs prepared from 5,6-dimethoxyindole (1 a and 2 a), 5,6-dibenzyloxyindole (1 b,c and 2 b,c), and 6-hydroxyindole (1 d and 2 d); a detailed characterization of their optoelectronic properties with the support of quantum chemical calculations based on TD-DFT; preliminary evidence of self-assembly behavior in solution; the applications of these TATs as emitting materials in OLED devices.…”

Synthesis and fluorescence emission properties of 1,3,6,8-tetraarylpyrenes

“…The C9 site of the fluorene molecule can be easily functionalized, which provides for the possibility of improved solubility and processability, and of controlling the excimer formation in the excited state [22][23][24]. Recently, fluorene-based compounds have been extensively used as thermally stable and efficient emissive OLED materials [2529] and as high carrier transport organic field-effect transistors (OFETs) material [30][31][32].…”

Star-shaped conjugated oligoelectrolyte for bioimaging in living cells

“…Unfortunately, so far water-soluble hyperbranched conjugated polymers are rarely developed, although their organicsoluble counterparts such as three or six-armed polymers [14,15] and so on, have been explored for use in organic electronics in many literatures [16]. Notably, Wang et al [12] and Li et al [17] have synthesized a series of water-soluble hyperbranched polymers such as star-shaped glycosylated conjugated, hyperbranched conjugated polyelectrolyte and so on for cell imaging recently.…”