AUTHOR=Khan Muhammad Usman , Khalid Muhammad , Asim Sumreen , Momina  , Hussain Riaz , Mahmood Khalid , Iqbal Javed , Akhtar Muhammad Nadeem , Hussain Amjad , Imran Muhammad , Irfan Ahmad , Ali Akbar , Rehman Muhammad Fayyaz ur , Jiang Yang , Lu Changrui 

TITLE=Exploration of Nonlinear Optical Properties of Triphenylamine-Dicyanovinylene Coexisting Donor-π-Acceptor Architecture by the Modification of π-Conjugated Linker

JOURNAL=Frontiers in Materials

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2021.719971

DOI=10.3389/fmats.2021.719971

ISSN=2296-8016

ABSTRACT=<p>High-tech electronic, optics, and storage devices require organic compounds with nonlinear optical (NLO) properties. This study designed D-π-A based dyes with donor triphenylamine (TPA) and acceptor dicyanovinylene (DCV) species by structurally modifying π-conjugated linkers. Our density functional theory (DFT) computations analyzed the impact of structural variations on the nonlinear optical (NLO) response of newly designed dyes. The B3LYP/6-31G(d,p) level determined the quantic chemical insights: frontier molecular orbital (FMOs), natural bond orbitals (NBOs), and nonlinear optical (NLO) properties of the designed dyes (DPTM-1 to DPTM-12). UV-Vis analysis based on the TD-DFT/CAM-B3LYP/6-311+G(d,p) level explored the optoelectronic properties. <bold>DPTM-1</bold> and <bold>DPTM-5</bold> showed the highest red-shifted absorption band at 519 and 506 nm<italic>.</italic> NBO analysis shows that DPTM-1 to DPTM-12 dyes have positive values for all donors (D) and π-spacers but negative values for acceptors (A). The π-spacers act as a conveyer between donor and acceptor moieties; thus, electrons were transferred smoothly from D to A units, which resulted in a charge separation state. Our calculations show the extent of NLO response in terms of electronic transitions, polarizability &lt;<italic>α</italic>&gt;, and first hyperpolarizability (<italic>β</italic>) values. The highest value of <italic>β</italic><sub><italic>total</italic></sub> was 110,509.23 <italic>a.u.</italic> manifested in <bold>DPTM-6</bold> due to 2,5-dimethyloxazole as a second π-linker, twice that of <bold>R</bold> (66,275.95 <italic>a.u.</italic>). Also, <bold>DPTM-6</bold> and <bold>DPTM-8</bold> exhibit the lowest energy band gap of 2.06 and 2.04 <italic>eV</italic>, respectively. In short, all DPTM-1 to DPTM-12 dyes manifested maximum absorption, lowest energy band gap, greater charge transfer from donor to the acceptor, and better first hyperpolarizability values as compared to the R and showed good NLO response. The present work represents new compounds with remarkable NLO properties and their applications in modern high-tech devices.</p>