Third-Order Nonlinear Optical Behavior of Novel Polythiophene Derivatives Functionalized with Disperse Red 19 Chromophore

Abstract

Two copolymers of 3-alkylthiophene (alkyl = hexyl, octyl) and a thiophene functionalized with disperse red 19 (TDR19) as chromophore side chain were synthesized by oxidative polymerization. The synthetic procedure was easy to perform, cost-effective, and highly versatile. The molecular structure, molecular weight distribution, film morphology, and optical and thermal properties of these polythiophene derivatives were determined by NMR, FT-IR, UV-Vis GPC, DSC-TGA, and AFM. The third-order nonlinear optical response of these materials was performed with nanosecond and femtosecond laser pulses by using the third-harmonic generation (THG) andZ-scan techniques at infrared wavelengths of 1300 and 800 nm, respectively. From these experiments it was observed that although the TRD19 incorporation into the side chain of the copolymers was lower than 5%, it was sufficient to increase their nonlinear response in solid state. For instance, the third-order nonlinear electric susceptibility (χ3) of solid thin films made of these copolymers exhibited an increment of nearly 60% when TDR19 incorporation increased from 3% to 5%. In solution, the copolymers exhibited similar two-photon absorption cross sectionsσ2PAwith a maximum value of 8545 GM and 233 GM (1 GM = 10−50 cm4 s) per repeated monomeric unit.

Nonlinear Optical Pigments. Two-Photon Absorption in Crosslinked Conjugated Polymers and Prospects for Remote Nonlinear Optical Thermometry

“…From the processing point of view, polymers and polymeric materials appear to be exceptionally versatile as well, as some of them can be prepared in the form of liquid solutions or dispersions but also can be readily processed as powders, fibers, and films, and some selected examples of them can be obtained as single crystals. Accordingly, favorable optical and physicochemical properties of polymers created a fertile niche for investigation of various aspects of their NLO properties, such as electro-optic phenomena, i.e., the linear electro-optic effect (Pockels effect) [15], the quadratic electro-optic effect (optical Kerr effect) [16][17][18], parametric energy conversion in second-harmonic [11][12][13][14][19][20][21] and third-harmonic generation [22][23][24][25][26] variants, and finally the two-photon absorption phenomenon (2PA) [26][27][28][29][30][31], which is at the focus of this paper.…”

Light-Induced Thermal and Optical Behavior of Functionalized Side-Chain Push–Pull Azo Polymer Thin Films

“…The most commonly studied physical properties of azo polymers are still the optical ones. − Induced by UV/vis light, the dynamics of the absorption changes regarding trans and cis states, as well as the dynamics of the optical spectra changes during the return from the cis to trans states, are also investigated. ,,,− There have been few works so far on the light-switching electrical ,, and thermal conductance , of azo polymers. In ref , it has been discovered that for a layer of azo-PMMA, which is closed-packed on the sidewalls of horizontally aligned carbon nanotubes, its longitudinal and vertical electrical conductivities increased up to 154 and 168%, respectively, after the UV irradiation and transition to the cis state.…”