Tuning the lifetime from molecular engineering of carbazole donor based metal-free organic dyes for dye sensitized solar cells – A computational approach

Transition metal-catalyzed regioselective functionalization of carbazoles and indolines with maleimides

The directing group-assisted regioselective C-H activation of carbazoles and indolines is achieved via transition metal-catalyzed reactions. This C-H functionalization protocol provides a rapid approach to install diversely functionalized succinimide groups at the C-1 position of the carbazole moiety. In addition, this protocol demonstrates the intrinsic reactivity of indolines in providing C-2 succinimide-substituted indoles via cascade direct oxidation and C-H functionalization. This protocol also provides C-7 succinimide-substituted indolines under mild reaction conditions. The features of this reaction include a wide substrate scope and excellent regioselectivity for the installation of the succinimide moiety on biologically interesting molecules.

The role of the donor group and electron-accepting substitutions inserted in π-linkers in tuning the optoelectronic properties of D-π-A dye-sensitized solar cells: a DFT/TDDFT study

The design of low-cost and high-efficiency sensitizers is one of the most important factors in the expansion of dye-sensitized solar cells (DSSCs). To obtain effective sensitizer dyes for applications in dye-sensitized solar cells, a series of metal-free organic dyes with the D–π–A–A arrangement and with different donor and acceptor groups have been designed by using computational methodologies based on density functional theory (DFT) and time-dependent density functional theory (TD-DFT). We have designed JK-POZ(1–3) and JK-PTZ(1–3) D–π–A–A organic dyes by modifying the donor and π-linker units of the JK-201 reference dye. Computational calculations of the structural, photochemical properties and electrochemical properties, as well as the key parameters related to the short-circuit current density and open-circuit voltage, including light-harvesting efficiency (LHE), singlet excited state lifetime (τ), reorganization energies (λ_total), electronic injection-free energy (ΔG^inject) and regeneration driving forces (ΔG^reg) of dyes were calculated and analyzed. Moreover, charge transfer parameters, such as the amount of charge transfer (q^CT), the charge transfer distance (D^CT), and dipole moment changes (μ^CT), were investigated. The results show that ΔG^reg, λ_max, λ_total and τ of JK-POZ-3 and JK-PTZ-3 dyes are superior to those of JK-201, indicating that novel JK-POZ-3 and JK-PTZ-3 dyes could be promising candidates for improving the efficiency of the DSSCs devices.

A series of metal-free organic dyes with the D–π–A–A arrangement and with different donor and acceptor groups have been designed theoretically.

Role of π conjugation in n-hexylphenothiazine dyes for solar cell-a density functional theory approach

The N-hexylphenothiazine-based organic sensitizers are designed for Dye Sensitized Solar Cell (DSSC). The different π spacer (thiophene and cyanovinyl) groups were substituted in third and seventh position N-hexylphenothiazine. From the structural modifications, the π spacer effect was analyzed. The optoelectronic properties of the dyes were tuned by structural modifications. The optimized geometry, highest occupied molecular orbital and lowest unoccupied molecular orbital energy level, and absorption spectra were calculated. The natural bond orbital analysis gives the net electron transfer from the donor to acceptor. The electrochemical properties and light-harvesting efficiency of the designed dye sensitizers were calculated. The π spacer increase resulted in the redshift of the absorption peak. Based on the density functional theory and time dependant density functional theory calculations, the designed dye molecules are evaluated for DSSC application.