Solvent Effects on Intra-/Intermolecular Charge Transfer in Indoloquinoxaline-Based Dyes

Abstract

In this work, kinetics and dynamics of the functionality of indoloquinoxaline-based dye-sensitized solar cells (DSSCs), QX22− QX25, were investigated in gas and solvent media. Quantum chemistry properties of the dyes at the excited states show that each moiety of the (D) 2 −A−π−A system has a specific effect on the photovoltaic properties. Solvent effect analysis shows that among ethanol, toluene, tetrahydrofuran, and methylene dichloride, toluene is the preferred medium for intra-/intermolecular charge transfer, dynamically and kinetically. Moreover, the behavior of the light harvesting efficiency (LHE) and incident photon-to-current efficiency (IPCE) are not similar, due to a strong effect of the Gibbs energy of electron injection on the energy conversion efficiency. Finally, the dye composed of −COOH as the anchoring group and thiophene as the π-spacer is the best candidate to be applied in DSSC due to its better efficiency originated from a lower electrophilicity and electronic chemical potential.

Insight into incident photon to current conversion efficiency in chlorophylls

“…The performance of the NDSSCs was determined by the incident photon conversion to the current efficiency ( IPCE ) affected by the possibility of electron transfer between the frontier energy levels of the sensitizers and TiO 2 /photosensitizer interface, which is theoretically obtained by Equation ) [ 29 ] : where LHE is the light‐harvesting efficiency; η coll is the electron collection efficiency; and ϕ inj is the net electron injection efficiency, which is related to Gibbs energy of electron injection, Δ G inj. The LHE of the sensitizer can be expressed by Equation ) [ 30 ] : where f is the oscillator strength of the dye molecule at the maximum absorption.…”

“…The CT distance, D CT , and the overlap of e-h distribution, S, were obtained from the Multiwfn program. [28] The performance of the NDSSCs was determined by the incident photon conversion to the current efficiency (IPCE) affected by the possibility of electron transfer between the frontier energy levels of the sensitizers and TiO 2 /photosensitizer interface, which is theoretically obtained by Equation (1) [29] :…”

Insight into incident photon to current conversion efficiency in chlorophylls

“…The charge transfer distance, D CT , and the overlap of e-h distribution, S , were obtained from the Multiwfn program. [25] The performance of the NDSSCs was determined by the incident photon conversion to the current efficiency (IPCE ) affected by the possibility of electron transfer between the frontier energy levels of the sensitizers and TiO 2 /photosensitizer interface, which is theoretically obtained by Equation (1) [26] :…”

Role of Explicitly Included Solvents on Ultrafast Electron Injection and Recombination Dynamics at TiO2/Dye Interfaces

“…Arkan et al evaluated the medium effects of different kinds of solvents on the solar cell performance of indoloquinoxalinebased DSCs through applying with the polarizable continuum model (PCM). 9 However, although the PCM model have taken the shielding effect of solvents into consideration, it ignores real intermolecular among dyes, semiconductor substrate, and solvent molecules. Prezhdo et al 10 interface electron transfer (ET) into the sub-10 fs regime.…”

“…Various simple models have been adopted as proxies of renewable energy nanodevices in practical environments. Arkan et al evaluated the medium effects of different kinds of solvents on the solar cell performance of indoloquinoxaline-based DSCs through applying with the polarizable continuum model (PCM) . However, although the PCM model have taken the shielding effect of solvents into consideration, it ignores real intermolecular among dyes, semiconductor substrate, and solvent molecules.…”