In this study, a theoretical investigation of the photoinduced charge transfer (CT), electron injection, regeneration and Non-linear optical (NLO) of the A1-A4 structures were carried out for optoelectronic applications based on tetrahydroquinoline (C1-1) dye. Besides, a detailed assessment of the association among the electronic structures, chemical hardness, spectral and photovoltaic (PV) presentation were defined in DSSCs. Furthermore, this exploration purposes improved the electron-injection procedure, as well as the light-harvesting efficiency (LHE) of the dyes. For the research purpose, PO3H2, CONHOH, SO2H and OH (A1-A4) chromophores effects among the tetrahydroquinoline moieties related via a thiophene group were used as the electron acceptor group. The density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were executed on the designing dye molecules. The presentation of three functional groups (Becke’s three-parameter and Lee-Yang-Parr (B3LYP), coulomb-attenuating method-B3LYP (CAM-B3LYP) and Head-Gordon model (ωB97XD) were analyzed maximum absorption peak for C1-1. Here, TD-ɷB97XD with the 6-31G(d) combined functional and basis set were provided reliable effects to the C1-1. Therefore, newly designed A1-A4 dyes in absorption spectra were followed by TD-ɷB97XD method. Among these results, A1 dye displays red-shift and higher molar extinction coefficient than the other dyes and C1-1. It is specified that the PO3H2 have better PV properties, compared to literature. The NLO belongings of the A1-A4 sensitizers were derived in the polarizability and first-order hyperpolarizability. The calculated value of A1 dye has best for NLO presentation. The theoretically outcomes were intensely recommended that molecular proposal of the sensitizer has a vital role for the optoelectronic properties.

In this work, a series of phenothiazine based organic dye sensitizers for dye-sensitized solar cells (DSSCs) have been designed and screened. The electron-donor as a phenothiazine, cyanoacrylic acid as an electron acceptor based on donor-acceptor (D-A) as reference dye SB. So as to enhance the triple bond effect on spacer and acceptor moieties has been investigated based on SB dye. The substituent effect of the spacer and electron acceptor on the absorption spectra and photovoltaic (PV) properties have been investigated by the combination of density functional theory (DFT) and time‐dependent DFT (TD-DFT) method approaches. Different exchange-correlation functionals have been initially evaluated in order to establish an accurate methodology for calculating the excited state energy of the SB dye. Consequently, TD-CAM-B3LYP method and 6-311++G(d,p) basis set have used been the comparison of experimental value. From the calculated results, concluded that the phenothiazine-4-((7-ethynylbenzo[c][1, 2, 5]thiadiazol-4-yl)ethynyl)benzoic acid (PT-EBTEBA) dye was strongly grouped for more red-shift and electrons injected into semiconductors effectively. It is expected to provide some theoretical guidance on designing photosensitive with new metal-free organic dyes for application in DSSCs yielding highly efficient performance.