RESUMO
The investigation of dye-sensitized solar cells (DSSCs) based on different donor groups linked with cyanoacrylic acid electron acceptor by Selenophene as π-bridged (D-π-A) was performed based on density functional theory (DFT) time-dependent DFT (TDDFT). Different functional were tested W97XD, PBEPBE, CAM-B3LYP, and B3PW91, and compared with experimental results of the reference D1. The theoretical results with CAM-B3LYP functional at 6-311G (d,p) basis sets were capable of predicting the absorption maximum that has been reported experimentally. Calculations were made to establish the conformational orientation of the cyanoacrylic acid group and evaluate the effect of changing donor units' on the electronic properties of the ground state. Structural and electronic properties, along with the photovoltaic properties, were investigated. The LUMO and HOMO energy levels of these dyes can positively affect the process of electron injection and dye regeneration. Light-harvesting efficiency (LHE), injection driving force (ΔGinject), and total reorganization energy (total) were also discussed. To further support the previous proprieties, electronic excited state energies were obtained by TDDFT// CAM-B3LYP/6-311G(d,p) calculations. The calculated results of these dyes reveal that D8 dye possessing triphenylamine donor unit has the best electronic, optical properties, and photovoltaic parameters.
RESUMO
We show that a Z-transform-based time-response analysis of the electro-optical response of a crystal to a step voltage with a short rise time allows one to obtain the dispersion of the electro-optical coefficients over a wide frequency range. We describe the method employed and present the results obtained for the main electroptic coefficients (r22, r61, and rc) of a standard LiNbO3 crystal. We also show that this method is able to provide even small values of the electro-optic coefficient as well as the dispersion within a wide frequency range, which is limited only by the rise time of the step voltage.
