LED-Induced Polymerization (385, 405, and 455 nm) Using Star-Shaped Tris(4-(thiophen-2-yl)phenyl)amine Derivatives as Light-Harvesting Photoinitiators

Carbazole Electroactive Amorphous Molecular Material: Molecular Design, Synthesis, Characterization and Application in Perovskite Solar Cells

In perovskite photovoltaics (PSCs), the role of the hole transporting material (HTM) is highly important as it significantly influents to the global device’s performance and stability. Hole transporter ensures the extraction of hole at the perovskite/HTM interface and transport it towards the cathode. Thus, accurate molecular design affording to efficient and cost-effective HTM is of major interest. Small molecules having glass forming property is an attractive class as it can form morphologically stable thin film. Herein, a carbazole molecular glass bearing a polymerizable function was designed and synthetized. Its characteristics are suitable for application as HTM in PSCs. The preliminary photovoltaic application lead to device efficiency of 14–15% depending on the chemical composition of the perovskite employed. These promising results open the way to design new alternative molecular and polymeric HTMs suitable for solution processed hybrid solar cells.

Substituent Effects on Photoinitiation Ability of Monoaminoanthraquinone-Based Photoinitiating Systems for Free Radical Photopolymerization under LEDs

Three monoamino-substituted anthraquinone derivatives (AAQs), that is, 1-aminoanthraquinone (AAQ), 1-(methylamino)anthraquinone (MAAQ), and 1-(benzamido)anthraquinone (BAAQ), incorporated with various additives [e.g., triethanolamine (TEAOH) and phenacyl bromide (PhC(═O)CH₂ Br)] are investigated for their roles as photoinitiating systems of free radical photopolymerization of (meth)acrylate monomers upon the exposure to UV to green LEDs. The AAQs-based photoinitiating systems, AAQ/TEAOH/PhC(═O)CH₂ Br and BAAQ/TEAOH/PhC(═O)CH₂ Br photoinitiators exhibit the highest efficiency for the free radical photopolymerization of DPGDA under the irradiation of blue LED and UV LED, respectively, which is consistent with the extent of overlap between their absorption spectra and the emission spectra of the LEDs. AAQ/TEAOH/PhC(═O)CH₂ Br photoinitiator can also initiate the free radical photopolymerization of different (meth)acrylate monomers, with an efficiency dependent on the chemical structures of these monomers.

Free Radical Photopolymerization and 3D Printing Using Newly Developed Dyes: Indane-1,3-Dione and 1H-Cyclopentanaphthalene-1,3-Dione Derivatives as Photoinitiators in Three-Component Systems

The design of photoinitiating systems with excellent photochemical reactivities at 405nm LED is one of the obstacles to efficiently promote free radical polymerization in mild conditions (e.g., low light intensity, under air). Here, our actual search for new multicomponent photoinitiating systems at 405nm LED prompts us to develop new dyes based on push–pull structures. In the present paper, we chose two series of new dyes which possess indane-1,3-dione and 1H-cyclopenta naphthalene-1,3-dione groups as the electron-withdrawing groups, since they have the great potential to behave as sensitive and remarkable photoinitiators in vat photopolymerization/3D printing. When incorporated with a tertiary amine (ethyl dimethylaminobenzoate EDB, used as electron/hydrogen donor) and an iodonium salt (used as electron acceptor) as the three-component photoinitiating systems (PISs), and among a series of 21 dyes, 10 of them could efficiently promote the free radical photopolymerization of acrylates. Interestingly, steady state photolysis experiments revealed different behaviors of the dyes. Fluorescence experiments and free energy change calculations for redox processes were also carried out to investigate the relevant chemical mechanisms. Additionally, the formation of radicals from the investigated PISs was clearly observed by electron spin resonance (ESR) spin-trapping experiments. Finally, stereoscopic 3D patterns were successfully fabricated by the laser writing technique. In this work, the use of push–pull dyes based on the naphthalene scaffold as photoinitiators of polymerization is reported for the first time in a systematic study aiming at investigating the structure–performance relationship for irradiation carried out at 405 nm. By carefully selecting the electron donors used in the two series of push–pull dyes, novel and high-performance photoinitiating systems operating at 405 nm are thus proposed.

In silico rational design by molecular modeling of new ketones as photoinitiators in three-component photoinitiating systems: application in 3D printing

New photoinitiators for 3D printing were in silico developed by molecular modeling.

The photooxidative sensitization of bis(p-substituted diphenyl)iodonium salts in the radical polymerization of acrylates

The ability of two-component dyeing photoinitiating systems for the radical polymerization of 1,6-hexanediol diacrylate (HDDA) and 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate (TMPTA) is presented. The systems under study comprised a hemicyanine dye as a sensitizer and iodonium salts that played a role of a coinitiator. The kinetic parameters of the polymerization reaction, such as the rate of polymerization (R_p) and the degree of conversion of monomer (C_%), were estimated. The thermodynamic feasibility of an electron transfer process in the systems studied was verified and calculated using the Rehm–Weller equation. It was found that a benzoxazole derivative in the presence of iodonium salts effectively initiated the polymerization of acrylate monomers. The polymerization rates of about 10⁻⁷ s⁻¹ and the degree of conversion of acrylate groups from 20% to 50% were observed. The effects of photoinitiator structures on the initiating ability and spectroscopic properties of sensitizers are described in this article.

The ability of two-component dyeing photoinitiating systems for the radical polymerization of 1,6-hexanediol diacrylate (HDDA) and 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate (TMPTA) is presented.

Triphenylamine-Thienothiophene Organic Charge-Transport Molecular Materials: Effect of Substitution Pattern on their Thermal, Photoelectrochemical, and Photovoltaic Properties

Two readily accessible thienothiophene-triphenylamine charge-transport materials have been synthesized by simply varying the substitution pattern of the triphenylamine groups on a central thienothiophene π-linker. The impact of the substitution pattern on the thermal, photoelectrochemical, and photovoltaic properties of these materials was evaluated and, based on theoretical and experimental studies, we found that the isomer in which the triphenylamine groups were located at the 2,5-positions of the thienothiophene core (TT-2,5-TPA) had better π-conjugation than the 3,6-isomer (TT-3,6-TPA). Whilst the thermal, morphological, and hydrophobic properties of the two materials were similar, their optoelectrochemical and photovoltaic properties were noticeably impacted. When applied as hole-transport materials in hybrid perovskite solar cells, the 2,5-isomer exhibited a power-conversion efficiency of 13.6 %, much higher than that of its 3,6-counterpart (0.7 %) under the same standard conditions.

New violet to yellow light sensitive diketo pyrrolo–pyrrole photoinitiators: high performance systems with unusual bleaching properties and solubility in water

New high performance photoinitiating systems for visible light exhibiting excellent bleaching properties and water solubility are proposed.

Thioxanthone dicarboxamide derivatives as one-component photoinitiators for near-UV and visible LED (365–405 nm) induced photopolymerizations

A series of thioxanthone dicarboxamide derivatives containing hydrogen donors as one-component LED photoinitiators have been prepared.

Photopolymerization upon LEDs: new photoinitiating systems and strategies

The use of LEDs as novel and efficient light sources for the photopolymerization of various monomers (acylate, epoxy), interpenetrating polymer networks and thiols–ene, leads to the development of novel photoinitiating systems adapted for the LED emission.

Di(p-methoxyphenyl)amine end-capped tri(p-thiophenylphenyl)amine based molecular glasses as hole transporting materials for solid-state dye-sensitized solar cells

Star shaped hole conducting molecular glasses were synthetized and applied in solid state dye-sensitized solar cells.

New iodonium salts in NIR sensitized radical photopolymerization of multifunctional monomers

Efficiency of NIR sensitized radical photopolymerization depends on the dissociation of iodonium salts comprising anions with low coordination capability.