Theoretical Study of WS-9-Based Organic Sensitizers for Unusual Vis/NIR Absorption and Highly Efficient Dye-Sensitized Solar Cells

Abstract

Dye-sensitized solar cells (DSSCs) are the most promising low-cost photovoltaic devices. Whereas, the absorption bands of most organic sensitizers, the most vital component in DSSCs, are limited to a relatively narrow visible range. To obtain efficient sensitizer, a series of D–A−π–A metal-free dyes have been designed based on one of the best sensitizers WS-9 by modifying auxiliary acceptor and characterized theoretically. The results illustrate that introduction of auxiliary heterocycle acceptor is revealed to very narrow band gap (HOMO–LUMO), leading to an obvious red-shifted broad near-infrared absorption band in the range of 750–1950 nm compared to WS-9 (536 nm). The critical parameters in close connection with the short-circuit current density (J sc), open circuit voltage (V oc), including singlet excited state lifetime (τ), total dipole moments (μnormal), the conduction band of edge of the semiconductor substrate (ΔE CB), and regeneration driving forces (ΔG reg) are superior to those of WS-9. Therefore, these novel sensitizers would be a promising candidate for improving the performance of the DSSCs.

Photoactive layer based on T-shaped benzimidazole dyes used for solar cell: from photoelectric properties to molecular design

“…A dye with a longer lifetime in the excited state is expected to be more facile for the charge transfer37. The excited state lifetimes of the dye sensitizers can be calculated via the equation: τ  = 1.499/( fE 2 ), where E (cm −1 ) is the excitation energy of the different electronic states and f is oscillator strength of the electronic state38. The calculated lifetime (τ) of the first excited state are listed in Table 3, they followed the order of 7a(2.64 ns) > 7b(2.57 ns) > 7c(2.26 ns).…”

An Experimental and Theoretical Investigation of the Electronic Structures and Photoelectrical Properties of Ethyl Red and Carminic Acid for DSSC Application

“…The longer the excited state lifetime is, the longer the time of dyes maintains in the cationic form is, which is more conducive to the charge transfer [65,77]. The excited state lifetime of the dye can be evaluated via the following equation: $\mathrm{sans-serif\tau }=1.499∕f{E}^2$, where E is the excitation energy of the different electronic states (cm −1 ) and f is the oscillator strength corresponding to the electronic state [65]. The calculated excited state lifetimes of the two dyes are listed in Table 3.…”

Theoretical Investigation of Structural and Electronic Properties of Ruthenium Azopyridine Complexes Dyes for Photovoltaic Applications by Using DFT and TD-DFT Methods

“…Furthermore, the life time of the excited state is recorded in Table 3. It is admitted that a long-life time keeps the dye longer in the cationic state, which allows a greater charge transfer (Li, et al, 2015). Therefore, as shown in Table 3, the life time values of the excited state of the studied dyes are comprised between 59.95 ns and 245.93 ns.…”

“…In fact, the dye with a long life time of excited state will have an easy electron transfer. Therefore, the excited state lifetime of the dye can be evaluated via the following equation (Li, et al, 2015):…”