A General Synthetic Route to Indenofluorene Derivatives as New Organic Semiconductors

Abstract

A series of 2,6-disubstituted indenofluorene derivatives were obtained in high purity via a general route involving the Suzuki coupling reaction. The potential of these conjugated indenofluorenes as new organic semiconductors was demonstrated by the light-emitting diode reaching a high luminance of 1400 Cd/m 2 below 10 V.Conjugated aromatic compounds are potential candidates as organic semiconductors for use in thin-film transistors (TFTs) and light-emitting diodes (LEDs). By incorporation of strongly electronegative substituents such as fluorine 1 and cyano groups 2 into certain aromatic molecules, some important n-type compounds have been obtained for TFT applications. To develop organic LED devices (OLEDs) with uniform luminescence, saturated color, and low driving voltages, many material factors must be considered, such as emission efficiency, color purity, carrier mobility, thermal and chemical stability, and processability (for vapor-phase deposition). 3 Among those organic semiconductors known for transistor and OLED applications, the fluorene-based compounds, 4 oligomers, 5 and polymers 6 have received most attention, owing to their unique properties, availability, and processability. Since the substituted fluorenes are known to have relatively high band gaps and low HOMO levels, they are

(2,1‐a)‐Indenofluorene Derivatives: Syntheses, X‐ray Structures, Optical and Electrochemical Properties

“…[1,2] Of particular interest was the structurally related (1,2-b)-indenofluorene (1,2-b)-IF (Scheme 1), which possess some unique properties due to the longer planar p-terphenyl backbone: for example, increase of the quantum yield. Thus, the pioneering works of Scherfs and Müllens groups on (1,2-b)-IF [11][12][13][14][15] have paved the way to the development of such molecules in the field of organic electronics and the (1,2-b)-indenofluorenyl core is nowadays a useful and a widely studied building block not only for OLED applications [1,2,[16][17][18][19][20][21][22][23][24][25][26][27] but also for two-photon absorption [28] or OFET applications. [7,[29][30][31][32] On the contrary, the positional isomer of (1,2-b)-IF, namely (2,1-a)-indenofluorene (2,1-a)-IF, has been very seldom studied and has only been investigated for potential electronics applications very recently (Scheme 1).…”

Dispirofluorene–Indenofluorene Derivatives as New Building Blocks for Blue Organic Electroluminescent Devices and Electroactive Polymers

“…Indeed, its incorporation into polymer or oligomer backbones instead of F units has recently led to a strong enhancement of OLED properties. [3,6,25,[47][48][49][50] Moreover, it is known that spiro-linked molecules such as spirobifluorene (SBF) [51] exhibit greater morphological stability and more intense fluorescence, without any significant change in their absorption and fluorescence spectra compared to the nonspiro-linked parent compounds. [28] Another highly important characteristic, which holds for most of SBF compounds, is that they do not exhibit any emission bands beyond 500 nm.…”

Hybrid Organic/Inorganic Transistors Utilizing an Indenofluorene Derivative as Emitter

“…The base thickness is varied altering the distance between the substrate and the crucible in the metal evaporation chamber, achieving values of 180 Å, 230 Å, 330 Å, 410 Å and 450 Å. The organic semiconductor emitter, 2,6-diphenylindenofluorene (DPIF) [5], was deposited by thermal sublimation at 10 -6 Torr onto the base layer, presenting a thickness of 760 Å in all samples. In the sequence Au was evaporated on top of the DPIF layer.…”