Density functional theory characterization and design of high-performance diarylamine-fluorenedyes with different π spacers for dye-sensitized solar cells

Abstract

To rationalize the marked difference in the energy conversion efficiency of dye sensitized solar cells (DSSCs) based on organic dyes 1 and 2 different only in their p spacer, density functional theory (DFT) and time-dependent DFT calculations of the geometries, electronic structures and absorption spectra of the organic dyes before and after binding to titanium oxide were carried out. These enable us to determine factors such as dipole moments associated with the open-circuit photovoltage (V oc ), and to quantify parameters such as the light harvesting efficiency, the electron injection efficiency associated with the short-circuit photocurrent density (J sc ). The results reveal that compared to 2 with a thiazole spacer, 1 with a thiophene spacer could cause a red shift of the absorption spectrum, increase the oscillator strength and improve the driving force for electron injection, thus leading to the larger J sc , in good agreement with experimental data. As for V oc , our results stress that apart from the generally emphasized vertical dipole moment of the dyes pointing outward from the semiconductor surface, the number of photoinjected electrons from the dye to the semiconductor is also crucial to obtain high performance dyes with high V oc . After justifying the reliability of the quantum-chemical methods, we designed another four dyes with different p spacers to screen more efficient organic dyes. Fortunately, taking 1 as reference, we find that dye 4 with a thienothiophene spacer displays an enhanced J sc and V oc , indicating that it will be a more efficient diarylamine-fluorene-based organic dye used in DSSCs, which will play a theoretical guiding role in the design and synthesis of new organic dyes.

Molecular design of distorted push–pull porphyrins for dye-sensitized solar cells

“…Upon the adsorption of dyes onto the semiconductor, the Fermi level of the TiO 2 undergoes some displacement due to the injection of electrons to the CB, resulting in the increase in the density of electronic states [11]. The shift of the E CB could be expressed as the following [8,12,13]:…”

“…The J SC is the generation and collection of light-generated carriers that depend on the number of factors, one of which can be exemplified in the equation [8,9]:…”

A cascaded QSAR model for efficient prediction of overall power conversion efficiency of all-organic dye-sensitized solar cells

“…Five descriptors (11,13,14,16,18) calculated by 631G are retained by more than four feature selection methods for J SC . Likewise, eight descriptors (4,9,13,16,19,24,26,31) for V OC , seven descriptors (3,4,7,12,13,16,26) for FF, and ten descriptors (4,6,7,9,14,15,18,20,24,25) for PCE are also retained by more than four feature selection methods. Although the selected descriptors based on STO and 631G are different, the most important molecular descriptors, such as descriptors (18) for J SC , (4,16,24) for V OC , (3,16) for FF and (9) for PCE are retained by most of the feature selection methods for both 631G and STO calculations.…”

“…Recently, the molecular design of organic dyes using quantum chemical calculations has been adopted, leading to great achievements. [11][12][13] The "golden" combination of quantum chemical methods and machine learning methods can fully utilize the advantages of both methods. Quantum chemical methods can capture the physical essence of molecular systems, and machine learning methods can explore the central relationship between molecular structures and the target properties or observed activities through the quantum chemical molecular descriptors.…”

Metal‐Free Sensitizers Containing Hydantoin Acceptor as High Performance Anchoring Group for Dye‐Sensitized Solar Cells

“…For DSSCs, because of the same photoanodes and fabrication processing, the η coll could be considered as stable values. [26,27] The major factor on IPCE of these sensitizers would be related to the difference in the electron-injection efficiency. Another parameter, internal quantum efficiency (IQE, IQE = IPCE/LHE = Φ inj × η coll ), could represent the electron-injection efficiency of different sensitizers.…”