Quantum Chemical Exploration of A−π₁–D₁–π₂–D₂-Type Compounds for the Exploration of Chemical Reactivity, Optoelectronic, and Third-order Nonlinear Optical Properties

Abstract

Organic compounds exhibit significant nonlinear optical (NLO) properties and can be utilized in various areas like optical parameters, fiber optics, and optical communication. Herein, a series of chromophores (DBTD1–DBTD6) with an A−π1–D1–π2–D2 framework was derived from a prepared compound (DBTR) by varying the structure of π-spacer and terminal acceptor. The DBTR and its investigated compounds were optimized at the M06/6-311G(d,p) level of theory. Frontier molecular orbitals (FMOs), nonlinear optical (NLO) properties, global reactivity parameters (GRPs), natural bonding orbital (NBO), transition density matrix (TDM), molecular electrostatic potential (MEP), and natural population analysis (NPA) were accomplished at the abovementioned level to describe the NLO findings. DBTD6 has the lowermost band gap (2.131 eV) among all of the derived compounds. The decreasing order of highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energy gap values was DBTR > DBTD1 > DBTD2 > DBTD3 > DBTD4 > DBTD5 > DBTD6. The NBO analysis was carried out to describe noncovalent interactions such as conjugative interactions and electron delocalization. From all of the examined substances, DBTD5 showed the highest λmax value at 593.425 nm (in the gaseous phase) and 630.578 nm (in chloroform solvent). Moreover, the βtot and ⟨γ⟩ amplitudes of DBTD5 were noticed to be relatively greater at 1.140 × 10–27 and 1.331 × 10–32 esu, respectively. So, these outcomes disclosed that DBTD5 depicted the highest linear and nonlinear properties in comparison to the other designed compounds, which underlines that it could make a significant contribution to hi-tech NLO devices.

Theoretical Expedition for Enhancing Photovoltaic Performance: DFT Investigation of Benzo[c][1,2,5] thiadiazole-Based Scaffolds for Organic Solar Cells

“…FMO analysis is widely regarded as a crucial technique for calculating the possibility of intramolecular charge transmission (ICT) in a system. − FMOs are necessary tools for understanding the capability to transport charge and assisting in the transport of electric current. − Computationally, we have thoroughly investigated the molecules and found that higher λ max leads to a lower band gap. Molecules with higher λ max also require lower excitation energy for the transition from the HOMO to LUMO, thus holding a lower energy gap.…”

Exploration of nonlinear optical enhancement in acceptor–π–donor indacenodithiophene based derivatives via structural variations: a DFT approach

“…Hence, to estimates the effect of donor and acceptor groups on the linear and nonlinear response of TNPR and TNPD1-TNPD6, their dipole moment, hai, b tot and g tot were calculated and the results are displayed in Tables S36-S39 † and major tensors are listed in Table 6. The dipole moment (m total ), 62 average linear polarizability hai 63 and rst hyper-polarizability (b tot ) 64 values were calculated by the using eqn (3)- (5).…”

“…The NLO compounds may have high microscopic molecular nonlinearity ( β ), robust thermal stability, optimum photo stability, minimal optical absorption and low electrical interactions between molecules in a specific host matrix in order to produce acceptable device functioning. 5 Organic nonlinear optical materials are preferably used because of their extended π-electron systems. The donor–π–acceptor configuration with excellent polarization in organic molecules can be used to infer the intra-molecular charge transfer process, which exhibits significant NLO features.…”