ABSTRACT
Because of the increasing scarcity of fossil fuels and the growing need for energy, it has become necessary to research new renewable energy resources. In this study, five new high-performance materials (TP-FA1F-TP - TP-FA5F-TP) of the D-π-A-π-D configuration based on triphenylamine (TPA) were theoretically investigated by applying DFT and TD-DFT methods for future application as heterojunction organic solar cells (BHJ). The influence of the modification of the acceptor (A) of the parent molecule TP-FTzF-TP on the structural, electronic, photovoltaic and optical properties of the TP-FA1F-TP - TP-FA5F-TP organic molecules was investigated in detail. TP-FA1F-TP - TP-FA5F-TP showed Egap in the interval of 1.44-2.01 eV with λabs in the range of 536-774 nm, open-circuit voltage (Voc) values varied between 0.3 and 0.56 V and power conversion efficiencies (PCE) ranging from (3-6) %. Our results also show that the donor molecules suggested in this research exhibit an improved performance compared to the recently synthesized TP-FTzF-TP, such as a lowest HOMO energy, a smaller Egap, and a greater absorption spectrum, and can lead to higher performance. Indeed, this theoretical research could lead to the future synthesis of better compounds as active substances used in BHJ.
Subject(s)
Amines , Electrons , Density Functional Theory , Electronics , Renewable EnergyABSTRACT
Global energy consumption has increased due to population growth and economic development. Solar energy is one of the most important renewable energy sources for human consumption. In this research, four novel organic dyes (D2-D5) of the D-A-π-A structure based on triphenylamine (TPA) were studied theoretically using DFT and TD-DFT techniques for future usage as dye-sensitized solar cells (DSSCs). The effects of modifying the π-spacer of the reference molecule D1 on the structural, electronic, photovoltaic, and optical characteristics of the D2-D5 dyes were studied in detail. D2-D5 exhibited band gaps (E gap) in the range from 1.89 to 2.10 eV with λ abs in the range of 508 to 563 nm. The results obtained show that modifying the π-spacer of the dye D1 increased its hole injection and reinforced the intramolecular charge-transfer (ICT) impact, which resulted in a red-shifted ICT absorption with a greater molar extinction coefficient. The theoretically calculated open-circuit voltage (V oc) values ranged from 0.69 to 1.06 eV, while the light-harvesting efficiency (LHE) values varied from 0.95 to 0.99. Indeed, this theoretical research could guide chemists to synthesize effective dyes for DSSCs.
ABSTRACT
In this work, we theoretically studied ten organic dyes using the DFT and TD-DFT methods, where triphenylamine was used as the donor for the D1-D5 dyes, while the 2, 6-diphenyl-4H-pyranylidene donor was used for the D6-D10 dyes. Substituents (alkyl and methoxy) were also introduced into these donor groups. These dyes also include 1, 3, 4-oxadiazole and phenyl as a bridge π and cyanoacrylic acid as acceptor. The electronic and optical properties of all dyes have been calculated as EHOMO, ELUMO, EGAP, Voc (the open-circuit photovoltage), λmax, Eex, LHE (the light-harvesting efficiency) and ΔGinj (the free injection energy) in order to compare their performance as DSSC sensitizers. The donor effect of all dyes was discussed on the one hand and on the other hand the effects of the introduction of substituents (alkyl and methoxy) to the donor before and after binding to TiO2 cluster. The results show that the performance of the dyes using 2, 6-diphenyl-4H-pyranylidene as donor has improved compared with the rest of the dyes, which may improve the power conversion efficiency. Therefore, these dyes D6-D10 are good candidates for use as DSSC sensitizers.
