Design and computational analysis of benzothiadiazole-fluorene based molecules for organic light-emitting diodes and high-efficiency organic solar cells

Abstract

Based on the experimental chromophore BTD-OMe, a series of new organic molecules (BTD-OMe and BTD-M1-BTD-M5) were designed for use as active layers in organic light-emitting diodes (OLEDs) and organic solar cells. This study aims to examine the effect of different acceptor groups on the structural, photovoltaic, nonlinear optical (NLO), electrical, and optical properties of the newly synthesized BTD-OMe molecule, utilizing density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The theoretical study suggested that BTD-M5 has the lowest energy band-gap (1.826 eV), with bathochromic shifts of 766.422 nm and 743.845 nm in the chloroform and gas phases, respectively. These BTDMs compounds have very high initial hyperpolarizability (βtot) values and a spectacular NLO reaction. Compound BTD-M5 stands out among them with the greatest values of first hyperpolarizability (β_tot = 54.500 × 10⁻²⁹ esu) and average linear polarizability (⟨α⟩ = 13.072 × 10⁻²³ esu). These findings indicate that the entitled newly benzothiadiazole (BTD) and fluorene based compounds, particularly BTD-M5, show great promise as highly efficient candidates for researchers to synthesize. They have potential applications both as emissive layers in OLEDs and as highly effective materials in the field of organic solar cells.