Tunable Electroluminescence from Silicon-Containing Poly(p-phenylenevinylene)-Related Copolymers with Well-Defined Structures

Abstract

A new class of silicon-containing poly(p-phenylenevinylene)-related copolymers with a uniform π-conjugated segment regulated by organosilicon units was synthesized by the well-known Wittig reaction between the appropriate diphosphonium salts and the dialdehyde monomer such as terephthaldicarboxaldehyde, 2,5-thiophenedicarboxaldehyde, and N-(2-ethylhexyl)-3,6-diformylcarbazole. The resulting polymers were highly soluble in common organic solvents. They could spin cast onto various substrates to give highly transparent homogeneous thin films without heat treatment. Their glass transition temperatures were in the range of 104−119 °C. The UV−visible absorbance of the present polymers shows strong absorption bands at around 347−387 nm, which corresponds to the π−π* transition of the conjugated segments. Their maximum photoluminescence wavelengths for SiPPV analogues appeared around 420−480 nm in the blue emission region, except a silicon-containing poly(p-phenylenevinylene)-related copolymer having a thiophene unit showed a strong PL peak at 520 nm in the green emission region. In the case of the polymers containing a carbazole unit, their PL spectra show both the highest peak in the PL emissive band at 450 nm and an additional strong emissive band in the green region. The single-layer light-emitting diode of a Al/SiPhPPV or SiPhPVK/ITO glass is fabricated. The threshold voltage is in the range 6−12 V from the I−V curve. The electroluminescence (EL) spectrum of the SiPhPPV gives the highest peak in the EL emissive band at 450 nm, when the operating voltage of 9 V was applied. For the polymer containing a carbazole unit, the EL spectrum of the polymer shows the highest peak in the EL emissive band at 450 nm as well as an additional strong emissive band in the yellow region, when the operating voltage of 10 V was applied. Interestingly, the SiPhPVK gives a strong white emitting light, when the operating voltage of higher than 12 V was applied.

Solar‐Energy Production and Energy‐Efficient Lighting: Photovoltaic Devices and White‐Light‐Emitting Diodes Using Poly(2,7‐fluorene), Poly(2,7‐carbazole), and Poly(2,7‐dibenzosilole) Derivatives

“…Over the past decade, only a few papers have been reported for WLEDs based on poly(3,6‐carbazole)s and these data are summarized in Table 8. Park et al were able to synthesize new polymers with tuneable light emission going from red to white light 124. Very interesting structures were characterized in this article, namely P73 derivatives (Fig.…”

“…The first study on these polymers led to polymers with green‐ and red‐light emission. With the addition of phenyl side chains on the silicon atom, white‐light emission can be observed at 12 V 124. Unfortunately, no values relating to the performances of these devices were reported.…”

Efficient and bright non-doped blue light-emitting diodes based on glassy styrylcarbazoles

“…In the tetrahedral tetraphenylsilyl core, the δ-C/Si atoms effectively interrupt the regular π-conjugation system. The tetraphenylsilane prevents the red-shift of blue emission associated with the increase in conjugation length [46][47][48][49][50][51].…”

Highly Stereoselective Synthesis of Arylene‐Silylene‐Vinylene Polymers

“…[10] However, in the presence of ruthenium complexes which contain or generate [Ru À H] and [Ru À Si] bonds, such compounds as divinylsilanes, [11,12] divinyldisiloxanes, [11,12] divinyldisilazane [13] and bis(vinylsilyl)alkanes [14] undergo a silylative coupling (SC) polycondensation to linear products according to Scheme 2 (for a recent review, see nylene-silylene-vinylene and copolymers consisting of phenylene-silylene-vinylene-phenylene-vinylene fragments with well-defined structures [17] which are of growing interest due to their efficient photo-and electroluminescence properties. [4,16] Under suitable conditions, the mechanism of silylative coupling reaction of monovinylsilanes is well-established (for reviews, see [7,8,15] and involves a cleavage of the carbon-silicon ( ¼ C À Si) bond of the vinylsilane and the carbon-hydrogen ( ¼ C À H) bond of the olefin (e.g., styrene) or a second vinylsilane molecule (in the silylative homo-coupling) as shown in Scheme 3, for the stereoselective synthesis of trans-product.…”