Computational investigations on acceptor substituent influence of metal-free efficient chromophores for optoelectronic properties.

In this study, the computational studies of the POH, CONHOH, and SOH (A1-A3) molecules were investigated for optoelectronic applications on the basis of tetrahydroquinoline (C1-1) dye. Besides, a detailed calculation of the molecular structures, energy levels, driving force of injection, regeneration, non-linear optical (NLO) property, chemical hardness, excitation binding energy, light-harvesting efficiency (LHE), absorption spectra, and photovoltaic (PV) parameters were all discussed in details using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. The optoelectronic properties of C1-1-based A1-A3 molecules are originated to be tuned by changing the position of the acceptor. To get a maximum absorption spectrum of C1-1, Becke's three-parameter and Lee-Yang-Parr (B3LYP), Coulomb-attenuating method-B3LYP (CAM-B3LYP), and Head-Gordon model (ωB97XD) were used for the TD-DFT method. Results reveal that the TD-ɷB97XD and 6-31G(d) combined functionals were provided reliable effects to the C1-1. Therefore, absorption spectra of the A1-A3 dyes were followed by the TD-ɷB97XD/6-31G(d) techniques. The designed A1 (POH) dye displayed a smaller energy gap and red-shifted broadened spectra than the other dyes and C1-1 can be utilized to get a better PV properties. In addition, NLO properties of the A1-A3 chromophores were calculated by the polarizability and first-order hyperpolarizability. Consequently, A1 dye has a superior value of the NLO activity. This study will deliver a valuable reference to the upcoming molecular proposal of tetrahydroquinoline dyes for optoelectronic applications.