Donor–Acceptor–Donor-based π-Conjugated Oligomers for Nonlinear Optics and Near-IR Emission

Abstract

A family of multi-heterocycle donor–acceptor–donor (DAD) telechelic conjugated oligomers designed for two-photon absorption (2PA) and emission in the near-infrared (near-IR) were prepared, and the relationship between their spectral, structural, and electrochemical properties were investigated. These oligomers, based on electron-rich thiophene, phenylene, and 3,4-ethylenedioxythiophene (EDOT) units as donors along with electron-deficient benzothiadiazole or its derivative units as acceptors, have been characterized through linear absorbance and fluorescence measurements, nonlinear absorbance, cyclic voltammetry, and differential pulse voltammetry to demonstrate the evolution of narrow HOMO–LUMO gaps ranging from 1.05 to 1.95 eV, with the oligomers composed of EDOT and benzo[1,2-c,3,4-c′]bis[1,2,5]thiadiazole (BBT) exhibiting the narrowest gap. The absorption maxima ranges from 517 to 846 nm and the fluorescence maxima ranges from 651 to 1088 nm for the different oligomers. Z-scan and two-photon fluorescence were used to measure the frequency degenerate 2PA of the different oligomers. The oligomer’s 2PA cross sections ranged from 900–3500 GM, with the oligomer containing EDOT donor units and a BBT acceptor unit exhibiting the largest 2PA cross section. The use of these oligomers in red to near-IR emitting polymer light-emitting diodes (PLEDs) was demonstrated by blending the soluble emitting oligomers into a suitable host matrix. Energy transfer from the matrix to the emitting oligomer can be achieved, resulting in PLEDs with pure oligomer emission.

Photophysics and Nonlinear Absorption of Gold(I) and Platinum(II) Donor–Acceptor–Donor Chromophores

“…19 Apart from that, the D-A-D structural motif is popular for generating quadrupolar chromophores for applications not only in nonlinear absorption but also in optoelectronic devices such as organic solar cells. 4,20 Among different organometallic architectures, metal− acetylide-containing small molecules and polymers are of interest due to strong interactions between the metal d-orbitals and the π-system of the ligand mediated via the metal− acetylide linkage. 21 In the present investigation, we explored the properties of ET-BTD-TE (E = ethynylene, T = 3-hexyl-2,5-thienylene, BTD = 2,1,3-benzothiadiazole) containing organometallic complexes for optoelectronic properties as well as 2PA, where BTD acts as an acceptor and T acts as a donor (Chart 1).…”

Simulations of fluorescence solvatochromism in substituted PPV oligomers from excited state molecular dynamics with implicit solvent

“…The chemical structure of these molecules are shown in Figure 1 [22,23]. This class of conjugated materials is rapidly evolving in applications such as molecular electronics and nanotechnology or as photovoltaic and electrochromic devices [24][25][26]. The specific molecules studied here have been implicated as excellent candidates for lightemitting diodes, showing varied emission energies ranging across the optical spectrum [25,26].…”

Symmetrically Disubstituted Bithiophene Derivatives of 1,3,4-Oxadiazole, 1,3,4-Thiadiazole, and 1,2,4-Triazole – Spectroscopic, Electrochemical, and Spectroelectrochemical Properties

“…[1][2][3][4][5][6][7][8][9][10][11] Appropriate functionalization of these compounds make them solution processable and allows for precise tuning of their electronic, spectroscopic, electrochemical and mechanical properties. For example, molecules exhibiting high electron affinity (|EA|>3.9 eV) due to their low lying LUMO level are good candidates for the fabrication of air operating n-channel FETs.…”