First-Principles Investigations of Novel Guanidine-Based Dyes

Uzma Hashmat; Nasir Rasool; Samia Kausar; Ataf Ali Altaf; Sabiha Sultana; Asif Ali Tahir

doi:10.1021/acsomega.3c09182

First-Principles Investigations of Novel Guanidine-Based Dyes

ACS Omega. 2024 Mar 14;9(12):13917-13927. doi: 10.1021/acsomega.3c09182. eCollection 2024 Mar 26.

Authors

Uzma Hashmat^{1

2}, Nasir Rasool¹, Samia Kausar³, Ataf Ali Altaf^{4

5}, Sabiha Sultana^{2

6}, Asif Ali Tahir²

Affiliations

¹ Department of Chemistry, Government College University, Faisalabad 38000, Pakistan.
² Environment and Sustainability Institute (ESI), Faculty of Environment, Science and Economy, University of Exeter, Penryn Campus, TR10 9FE Cornwall, U.K.
³ Department of Chemistry, University of Gujrat, Hafiz Hayat Campus, Gujrat 50700, Pakistan.
⁴ Department of Chemistry, University of Okara, Okara 56300, Pakistan.
⁵ Department of Food Science, College of Agriculture and Life Sciences, Cornell University, Ithaca,New York 14853, United States.
⁶ Department of Chemistry, Islamia College University, Peshawar 25120, Pakistan.

Abstract

In the pursuit of finding efficient D-π-A organic dyes as photosensitizers for dye-sensitized solar cells (DSSCs), first-principles calculations of guanidine-based dyes [A1-A18] were executed using density functional theory (DFT). The various electronic and optical properties of guanidine-based organic dyes with different D-π-A structural modifications were investigated. The structural modification of guanidine-based dyes largely affects the properties of molecules, such as excitation energies, the oscillator strength dipole moment, the transition dipole moment, and light-harvesting efficiencies. The energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) is responsible for the reduction and injection of electrons. Modification of the guanidine subunit by different structural modifications gave a range of HOMO-LUMO energy gaps. Chemical and optical characteristics of the dyes indicated prominent charge transfer and light-harvesting efficiencies. The wide electronic absorption spectra of these guanidine-based dyes computed by TD-DFT-B3LYP with 6-31G, 6-311G, and cc-PVDZ basis sets have been observed in the visible region of spectra due to the presence of chromophore groups of dye molecules. Better anchorage of dyes to the surface of TiO₂ semiconductors helps in charge-transfer phenomena, and the results suggested that -COOH, -CN, and -NO₂ proved to be proficient anchoring groups, making dyes very encouraging candidates for DSSCs. Molecular electrostatic potential explained the electrostatic potential of organic dyes, and IR spectrum and conformational analyses ensured the suitability of organic dyes for the fabrication of DSSCs.