Position Of Fluorine Research Articles

Isomerism Effect of 3D Dimeric Acceptors for Non‐Halogenated Solvent‐Processed Organic Solar Cells with 20 % Efficiency

AbstractOrganic photovoltaic materials that can be processed via non‐halogenated solvents are crucial for the large‐area manufacturing of organic solar cells (OSCs). However, the limited available of electron acceptors with adequate solubility and favorable molecular packing presents a challenge in achieving efficient non‐halogenated solvent‐processed OSCs. Herein, inspired by the three‐dimensional dimeric acceptor CH8‐4, we employed a molecular isomerization strategy to synthesize its isomers, CH8‐4A and CH8‐4B, by tuning the position of fluorine (F) atom in the central unit. The differing intramolecular fluorine‐sulfur non‐covalent interactions among these isomers led to differences in molecular pre‐aggregation abilities (CH8‐4B<CH8‐4<CH8‐4A) in o‐xylene (o‐XY) solution, which significantly influence the film‐forming process and the resultant morphological characteristics. Among these, the blend film of CH8‐4, characterized by moderate molecular pre‐aggregation, achieved optimal bi‐continuous donor/acceptor phase separation. Consequently, the o‐xylene processed PM6 : CH8‐4 device achieved a power conversion efficiency (PCE) of 18.1 %, outperforming that of two other devices. By incorporating L8‐BO‐D as a guest acceptor, we attained an impressive PCE of 20.0 % for the CH8‐4‐based ternary device, alongside a high PCE nearing 16 % for the mini‐module (13.5 cm2). Our findings underscore the potential of isomerism in 3D dimer acceptors to enhance the performance of eco‐friendly OSCs.

Host-guest geometry in paramagnetic cavitands elucidated by 19F electron-nuclear double resonance.

Elucidating structural information of supramolecular host-guest systems is pivotal for understanding molecular recognition and designing functional materials. This study explores the binding modes of fluorinated benzylamine guests in cyclodextrin-based paramagnetic cavitands, employing Gd(III)-capped cyclodextrins (Gd-α-CD and Gd-β-CD, comprising six and seven glucopyranoside units, respectively) and high-field 19F electron-nuclear double resonance (ENDOR). The 19F ENDOR spectra revealed distinct behaviors based on the fluorine position and cyclodextrin cavity size. For para-fluorinated benzylamine guests, Gd-β-CD displayed a bimodal distribution of Gd-F distances, corresponding to two distinct binding modes, whereas Gd-α-CD exhibited a single binding mode. In contrast, meta-fluorinated benzylamines demonstrated a single binding mode for both Gd-α-CD and Gd-β-CD, underscoring the influence of cavity size and fluorine substitution in the guest on binding specificity. ENDOR measurements performed at the EPR central transition of Gd(III) are generally expected to yield Gd-F distances without orientation-specific details. Surprisingly, in Gd-CDs systems, an unexpected orientation selectivity was observed, enabling the extraction of both Gd-F distances and orientation of the guest molecule relative to the cavitand's Gd(III) zero-field splitting (ZFS) tensor. This two-faceted capability of 19F-ENDOR allows for determining host-guest complexation geometry and provides insights into ZFS orientation within the cavitand structure.

Isomerism Effect of 3D Dimeric Acceptors for Non-Halogenated Solvent-Processed Organic Solar Cells with 20 % Efficiency.

Organic photovoltaic materials that can be processed via non-halogenated solvents are crucial for the large-area manufacturing of organic solar cells (OSCs). However, the limited available of electron acceptors with adequate solubility and favorable molecular packing presents a challenge in achieving efficient non-halogenated solvent-processed OSCs. Herein, inspired by the three-dimensional dimeric acceptor CH8-4, we employed a molecular isomerization strategy to synthesize its isomers, CH8-4A and CH8-4B, by tuning the position of fluorine (F) atom in the central unit. The differing intramolecular fluorine-sulfur non-covalent interactions among these isomers led to differences in molecular pre-aggregation abilities (CH8-4B<CH8-4<CH8-4A) in o-xylene (o-XY) solution, which significantly influence the film-forming process and the resultant morphological characteristics. Among these, the blend film of CH8-4, characterized by moderate molecular pre-aggregation, achieved optimal bi-continuous donor/acceptor phase separation. Consequently, the o-xylene processed PM6 : CH8-4 device achieved a power conversion efficiency (PCE) of 18.1 %, outperforming that of two other devices. By incorporating L8-BO-D as a guest acceptor, we attained an impressive PCE of 20.0 % for the CH8-4-based ternary device, alongside a high PCE nearing 16 % for the mini-module (13.5 cm2). Our findings underscore the potential of isomerism in 3D dimer acceptors to enhance the performance of eco-friendly OSCs.

(General Student Poster Award Winner, 1st Place) Synthesis and F-Ion Conduction of Ba0.57M0.43F2.43 (M = Y, La, Nd, Sm, Bi) As Solid Electrolytes for All-Solid-State F-Ion Batteries

All-solid-state fluoride-ion batteries (FIBs) have attracted research attention because these batteries possess a high energy density surpassing the state-of-the-art Li-ion batteries.1 Yet, the lack of a fluoride-ion conductor with both highly ionic conductive and highly stable is one of the key bottlenecks in the development of FIBs. Conventionally, La0.9Ba0.1F2.9 (LBF) is used as a solid electrolyte in FIB. However, the cathodic stability of LBF limits the choice of anode materials unable to be below the reduction potential of LaF3/La as plating occurs. Our previous study showed that Ba4Bi3F17 (R−3) with a fluorite-like sublattice could form the disordered phase equivalent to a fluorite Ba0.57Bi0.43F2.43 (Fm−3m), enabling a fast fluoride-ion conduction comparable to LBF.2 By replacing Bi with the elements that have lower equilibrium fluorine activity, the electrolyte materials with higher stability could be anticipated. Therefore, in this study, mechanochemical synthesis was used to fabricate the disordered phases of Ba0.57M0.43F2.43 (M = Y, La, Nd, Sm, Bi) to study their electrochemical stability and F-ion conductivity.The materials were synthesized using a mechanochemical technique with a planetary ball mill at 600 rpm for 12 h under a static argon atmosphere. The resultant phases were characterized using synchrotron X-ray diffraction (XRD) and time-of-flight neutron powder diffraction (NPD) to study the fluorine position and distribution in the structure. Impedance measurements were performed using blocking electrodes to estimate the electrical conductivity of the materials, and the electronic insulation of the materials was confirmed by DC polarization. Cyclic voltammetry was used to estimate the electrochemical stability window of the materials in comparison with LBF using Pt and Pb as a working electrode and a counter electrode, respectively.Mechanochemical synthesis of the mixture of BaF2 and MF3 was shown to preserve the fluorite structure (Fm−3m) regarding the diffraction patterns. Electrochemical impedance spectroscopy showed the Nyquist plot of these materials as a semi-circle with a spike feature at low frequencies which is a typical response of ionic conduction under the blocking electrode scheme. The Arrhenius plot of the materials exhibited a slight difference in conductivity where the order of conductivity could be ranged from M = Bi > La > Nd > Sm > Y. The electrochemical stability window of the materials measured by cyclic voltammetry revealed that the stability of materials is in the order M = Y > Sm > LBF > Nd > La > Bi. The extraordinarily wide windows of M = Y and Sm exceeding that of LBF without a reduction peak open the possibility towards the use of high-energy anode materials, which will increase the energy density of the battery.

Dimerized M‐Series Acceptors with Low Diffusion Coefficients for Efficient and Stable Polymer Solar Cells

AbstractAs the simplest oligomeric acceptors, dimerized acceptors (DAs) are easier to synthesize, and more importantly, they can retain good intermolecular interaction and photovoltaic properties of their parent small‐molecule acceptors (SMAs). Nevertheless, currently most efficient DAs are derived from banana‐shaped acceptors and they might suffer from inferior device stability with high diffusion coefficients. Herein, we design and synthesize two planar DAs (DMT‐FH and DMT‐HF) by bridging two linear‐shaped M‐series SMAs with a thiophene unit. The effects of fluorination position on the diffusion coefficients, power conversion efficiencies (PCEs) and stability of the DAs are systematically studied. Our results suggest that DMT‐HF with fluorination on the ending indanone groups shows enhanced intermolecular interactions, improved PCE and stability compared with the counterpart (DMT‐FH) with fluorination on the central indanone groups. Further optimization on the DMT‐HF‐based devices yields an outstanding PCE of 17.17 %, which is the highest among all linear‐shaped SMA‐based DAs. Notably, with the low diffusion coefficient (3.36×10−24 cm2 s−1) of DMT‐HF, the resulting device retains over 93 % of the initial PCE after 5000 h of continuous heating at 85 °C, suggesting its excellent thermal stability. The results highlight the importance of intermolecular interaction and fluorination for achieving efficient and stable polymer solar cells.

Dimerized M-Series Acceptors with Low Diffusion Coefficients for Efficient and Stable Polymer Solar Cells.

As the simplest oligomeric acceptors, dimerized acceptors (DAs) are easier to synthesize, and more importantly, they can retain good intermolecular interaction and photovoltaic properties of their parent small-molecule acceptors (SMAs). Nevertheless, currently most efficient DAs are derived from banana-shaped acceptors and they might suffer from inferior device stability with high diffusion coefficients. Herein, we design and synthesize two planar DAs (DMT-FH and DMT-HF) by bridging two linear-shaped M-series SMAs with a thiophene unit. The effects of fluorination position on the diffusion coefficients, power conversion efficiencies (PCEs) and stability of the DAs are systematically studied. Our results suggest that DMT-HF with fluorination on the ending indanone groups shows enhanced intermolecular interactions, improved PCE and stability compared with the counterpart (DMT-FH) with fluorination on the central indanone groups. Further optimization on the DMT-HF-based devices yields an outstanding PCE of 17.17 %, which is the highest among all linear-shaped SMA-based DAs. Notably, with the low diffusion coefficient (3.36×10-24 cm2 s-1) of DMT-HF, the resulting device retains over 93 % of the initial PCE after 5000 h of continuous heating at 85 °C, suggesting its excellent thermal stability. The results highlight the importance of intermolecular interaction and fluorination for achieving efficient and stable polymer solar cells.

Efficient Synthesis of High-Performance Wide-Bandgap Polymers Based on Difluoronaphthodithiophene: Fluorination Position Impact on Photovoltaic Performance

Efficient Synthesis of High-Performance Wide-Bandgap Polymers Based on Difluoronaphthodithiophene: Fluorination Position Impact on Photovoltaic Performance

Control of Multi-Fluorination Number and Position in D-π-A Type Polymers and Their Impact on High-Voltage Organic Photovoltaics.

Exploring the structure-performance relationship of high-voltage organic solar cells (OSCs) is significant for pushing material design and promoting photovoltaic performance. Herein, we chose a D-π-A type polymer composed of 4,8-bis(thiophene-2-yl)-benzo[1,2-b:4,5-b']dithiophene (BDT-T) and benzotriazole (BTA) units as the benchmark to investigate the effect of the fluorination number and position of the polymers on the device performance of the high-voltage OSCs, with a benzotriazole-based small molecule (BTA3) as the acceptor. F00, F20, and F40 are the polymers with progressively increasing F atoms on the D units, while F02, F22, and F42 are the polymers with further attachment of F atoms to the BTA units based on the above three polymers. Fluorination positively affects the molecular planarity, dipole moment, and molecular aggregations. Our results show that VOC increases with the number of fluorine atoms, and fluorination on the D units has a greater effect on VOC than on the A unit. F42 with six fluorine atom substitutions achieves the highest VOC (1.23 V). When four F atoms are located on the D units, the short-circuit current (JSC) and fill factor (FF) plummet, and before that, they remain almost constant. The drop in JSC and FF in F40- and F42-based devices may be attributed to inefficient charge transfer and severe charge recombination. The F22:BTA3 system achieves the highest power conversion efficiency of 9.5% with a VOC of 1.20 V due to the excellent balance between the photovoltaic parameters. Our study provides insights for the future application of fluorination strategies in molecular design for high-voltage organic photovoltaics.

2‐ and 3‐Fluorocyclobutane Building Blocks for Organic and Medicinal Chemistry

Multigram synthesis of 3‐fluorinated cyclobutane building blocks has been disclosed. The proposed synthetic schemes were based on the nucleophilic fluorination and eventually led to 3‐fluorocyclocutanecarboxylic acid as a key target compound and intermediate. Further functional group transformations provided monofluorinated cyclobutane‐derived alcohols, amines, bromides, thiols, sulfonyl chlorides, etc. Furthermore, the synthesis of diastereopure cis‐ and trans‐isomeric 2‐ and 3‐fluorocyclobutane­carboxylic acids and amines was also performed. In both cases, diastereomer separation was used to obtain pure stereoisomers. The effect of the fluorine position and relative spatial orientation on the physicochemical properties of the corresponding monoflurinated derivatives was studied by measurements of pKa and logP values.

Identification of Dual Inhibitors Targeting Main Protease (Mpro) and Cathepsin L as Potential Anti-SARS-CoV-2 Agents.

In this structure-activity relationship (SAR) study, we report the development of dual inhibitors with antiviral properties targeting the SARS-CoV-2 main protease (Mpro) and human cathepsin L (hCatL). The novel molecules differ in the aliphatic amino acids at the P2 site and the fluorine position on the phenyl ring at the P3 site. The identified dual inhibitors showed Ki values within 1.61 and 10.72 μM against SARS-CoV-2 Mpro; meanwhile, Ki values ranging from 0.004 to 0.701 μM toward hCatL were observed. A great interdependency between the nature of the side chain at the P2 site and the position of the fluorine atom was found. Three dual-targeting inhibitors exhibited antiviral activity in the low micromolar range with CC50 values >100 μM. Docking simulations were executed to gain a deeper understanding of the SAR profile. The findings herein collected should be taken into consideration for the future development of dual SARS-CoV-2 Mpro/hCatL inhibitors.

Multifunctional Regioisomeric Passivation Strategy for Fabricating Self-Driving, High Detectivity All-Inorganic Perovskite Photodetectors.

The fluorination of the aromatic multifunctional Lewis base passivation strategy has been demonstrated recently as an effective approach to markedly enhance the performance of perovskite photovoltaic devices. However, the regulation mechanisms of the passivation efficiency by varying the functional group position of fluorine (F) in the regioisomers have received little attention and inadequate research. Herein, a pair of bifluorine-substituted aminobenzoic acid regioisomers [3-amino-2,6-difluorobenzoic acid (13-FABA) and 4-amino-3,5-difluorobenzoic acid (14-FABA)] were employed to investigate the passivation effects of Lewis bases dependent on behaviors of the ortho/meta-substituted position of fluorine. The density functional theory calculation on electron cloud density, interaction energy, and the basicity of Lewis bases combined with experimental evidence reveal that the ortho-effect induced by fluorine substitution weakens the passivating effect of 13-FABA Lewis base and induces its molecular propensity to form internal salts, accelerating the degradation and deterioration of the device performance. Conversely, 14-FABA with meta-connected fluorine atoms exhibit superior efficacy in suppressing defects and enhancing hydrophobicity. Eventually, the 14-FABA-modified photodetectors (PDs) achieved a high detectivity of 1.69 × 1013 Jones, the comparatively lower dark current density of 2.2 × 10-10 A/cm2 among all-inorganic perovskite PD systems. Our work has not only clarified the fundamental mechanisms of the F-substituted position effects of Lewis base on suppressing defects but also provided a promising passivation strategy for perovskite films via designing the regioisomeric atoms in a multifunctional Lewis base molecule.

Effect of Fluorination Position on the Crystalline Structure and Stretchability of Intrinsically Stretchable Polymer Semiconductors.

A clear understanding of the structure-property relationship of intrinsically stretchable polymer semiconductors (ISPSs) is essential for developing high-performance polymer-based electronics. Herein, we investigate the effect of the fluorination position on the crystalline structure, charge-carrier mobility, and stretchability of polymer semiconductors based on a benzodithiophene-co-benzotriazole configuration. Although four different polymer semiconductors showed similar field-effect mobilities for holes (μ ≈ 0.1 cm2 V-1 s-1), polymer semiconductors with nonfluorinated backbones exhibited improved thin-film stretchability confirmed with crack onset strain (εc ≈ 20%-50%) over those of fluorinated counterparts (εc ≤ 10%). The enhanced stretchability of polymer semiconductors with a nonfluorinated backbone is presumably due to the higher face-on crystallite ratio and π-π stacking distance in the out-of-plane direction than those of the other polymer semiconductors. These results provide new insights into how the thin-film stretchability of polymer semiconductors can be improved by using precise molecular tailoring without deteriorating electrical properties.

Organic Fluorine Compounds and Their Uses as Molecular MR-Based Temperature Sensors.

The interest in fluorinated substances has increased significantly in recent decades due to their diverse properties and possible uses. An important analytical method in this context is NMR spectroscopy, which provides information on the structure as well as on intermolecular interactions or generally on changes in the environment of the nucleus under consideration. A physical quantity that is of great importance in most studies is temperature. However, this is not always easy, e. g. in shielded systems or within an organism. However, the application potential in chemical reactors or in medical diagnosis and therapy is very high and for this reason 13 fluorinated organic compound were chosen for a first 19 F NMR signal temperature sensitivity examination for determination of local temperatures in solution. Polyfluorinated molecules with separate 19 F MR signals are particularly suitable for temperature determination. Those can be serve as internal error-correcting thermometers without the need of a reference substance. Under these conditions, a 19 F MR signal shift of up to 0.03 ppm/K was detectable. Fluorine position and chemical environment were very important for the temperature sensitivity.

Structural Isomer of Fluorinated Ruddlesden-Popper Perovskites Toward Efficient and Stable 2D/3D Perovskite Solar Cells.

Defect passivation using two-dimensional (2D)-layered perovskites with organic spacers on 3D bulk perovskites has been proposed as an effective strategy to improve perovskite solar cell stability and efficiency. Specifically, fluorination of the organic spacers has been employed due to the resulting hydrophobic nature and the defect passivation characteristics. In addition to the type of functional groups attached to the spacer molecules, conformational changes of fluorine isomers on layered perovskites can provide an extended strategy to control a variety of opto-electrical properties related to the interlayer spacing. As a model system for the structural isomer of fluorinated spacers, meta-CF3 and para-CF3 groups anchored to phenethylammonium iodide (PEAI) spacer molecules are employed to synthesize 2D perovskites and to investigate their full potential as an interfacial modifier for perovskite solar cells. The fluorination position change leads to altered opto-electrical characteristics in layered perovskites. Although they possess identical functional groups, the different orientations of the functional groups used in the perovskite layer deposited on the 3D perovskite absorber result in distinct electrical properties of 2D/3D heterostructures due to dissimilar intermolecular interactions. The 2D perovskite with meta-CF3-PEAI spacers exhibits an enhancement of the charge transport in the out-of-plane orientation and an improved suppression of the trap states of 3D perovskites while also providing a more favorable energy alignment for efficient charge transfers. Theoretical simulations are consistent with the experimental results. The structural isomers of fluorination anchoring to spacer cations alter the structural configuration of the spacer as well as the interlayer spacing that can improve the performance and the stability of 2D/3D perovskite solar cells.

Rational Design of Fluorinated Electrolytes for Low Temperature Lithium‐Ion Batteries

AbstractNonaqueous carbonate electrolytes are commonly used in commercial lithium‐ion battery (LIB). However, the sluggish Li+ diffusivity and high interfacial charge transfer resistance at low temperature (LT) limit their wide adoption among geographical areas with high latitudes and altitudes. Herein, a rational design of new electrolytes is demonstrated, which can significantly improve the low temperature performance below −20 °C. This electrolyte is achieved by tailoring the chemical structure, i.e., altering the fluorination position and the degree of fluorination, of ethyl acetate solvent. It is found that fluorination adjacent to the carbonyl group or high degree of fluorination leads to a stronger electron‐withdrawing effect, resulting in low atomic charge on the carbonyl oxygen solvating sites, and thus low binding energies with Li+ ions at LT. The optimal electrolyte 2,2,2‐trifluoroethyl acetate (EA‐f) shows significantly improved cycle life and C‐rate of a NMC622/graphite cell when cycled at −20 °C and −40 °C, respectively. In addition to superior LT performance, the electrolyte is nonflammable and tolerant for high voltage charging all owing to its fluorine content. This work provides guidance in designing next‐generation electrolytes to address the critical challenge at subzero temperatures.

Chemical Doping by Fluorination and Its Impact on All Energy Levels of π-Conjugated Systems.

Halogenation of organic molecules causes chemical shifts of C1s core-level binding energies that are commonly used as fingerprints to identify chemical species. Here, we use synchrotron-based X-ray photoelectron spectroscopy and density functional theory calculations to unravel such chemical shifts by examining different partially fluorinated pentacene derivatives. Core-level shifts occur even for carbon atoms distant from the fluorination positions, yielding a continuous shift of about 1.8 eV with increasing degree of fluorination for pentacenes. Since also their LUMO energies shift markedly with the degree of fluorination of the acenes, core-level shifts result in a nearly constant excitation energy of the leading π* resonance as obtained in complementary recorded K-edge X-ray absorption spectra, hence demonstrating that local fluorination affects the entire π-system, including valence and core levels. Our results thus challenge the common picture of characteristic chemical core-level energies as fingerprint signatures of fluorinated π-conjugated molecules.

Deciphering reduction stability of sulfone and fluorinated sulfone electrolytes:Insight from quantum chemical calculations

Sulfones and fluorinated sulfones are preferred in high-voltage lithium-ion batteries, but the reasons for their decreased stability in various lithium salt electrolytes remain unknown. Twelve different sulfone-based solvents, Li+-solvent and Li+-solvent-anion complexes were studied herein via quantum chemical calculations to compare reduction potentials and initial decomposition reactions. The results show that position of fluorination has significant effect on the reduction potentials and significant elongation (over 50 %) of SC bond is responsible for the abnormal increase of reduction potential for α-fluorinated sulfones, leading to their poor reduction stability. Li+-solvent-FSI-/PF6- complexes have the preference for anionic reduction, spontaneous defluorination and production of LiF, which can produce a LiF-rich solid-electrolyte interface on graphite. Therefore, most β-fluorinated sulfones and regular sulfones are stable to graphite at high lithium salt concentrations, while only β-fluorinated sulfones are stable to graphite at low salt concentrations.

Isomeric Activity Cliffs-A Case Study for Fluorine Substitution of Aminergic G Protein-Coupled Receptor Ligands.

Currently, G protein-coupled receptors (GPCRs) constitute a significant group of membrane-bound receptors representing more than 30% of therapeutic targets. Fluorine is commonly used in designing highly active biological compounds, as evidenced by the steadily increasing number of drugs by the Food and Drug Administration (FDA). Herein, we identified and analyzed 898 target-based F-containing isomeric analog sets for SAR analysis in the ChEMBL database-FiSAR sets active against 33 different aminergic GPCRs comprising a total of 2163 fluorinated (1201 unique) compounds. We found 30 FiSAR sets contain activity cliffs (ACs), defined as pairs of structurally similar compounds showing significant differences in affinity (≥50-fold change), where the change of fluorine position may lead up to a 1300-fold change in potency. The analysis of matched molecular pair (MMP) networks indicated that the fluorination of aromatic rings showed no clear trend toward a positive or negative effect on affinity. Additionally, we propose an in silico workflow (including induced-fit docking, molecular dynamics, quantum polarized ligand docking, and binding free energy calculations based on the Generalized-Born Surface-Area (GBSA) model) to score the fluorine positions in the molecule.

The Impact of Backbone Fluorination and Side-Chain Position in Thiophene-Benzothiadiazole-Based Hole-Transport Materials on the Performance and Stability of Perovskite Solar Cells.

Perovskite solar cells (PSCs) currently reach high efficiencies, while their insufficient stability remains an obstacle to their technological commercialization. The introduction of hole-transport materials (HTMs) into the device structure is a key approach for enhancing the efficiency and stability of devices. However, currently, the influence of the HTM structure or properties on the characteristics and operational stability of PSCs remains insufficiently studied. Herein, we present four novel push-pull small molecules, H1-4, with alternating thiophene and benzothiadiazole or fluorine-loaded benzothiadiazole units, which contain branched and linear alkyl chains in the different positions of terminal thiophenes to evaluate the impact of HTM structure on PSC performance. It is demonstrated that minor changes in the structure of HTMs significantly influence their behavior in thin films. In particular, H3 organizes into highly ordered lamellar structures in thin films, which proves to be crucial in boosting the efficiency and stability of PSCs. The presented results shed light on the crucial role of the HTM structure and the morphology of films in the performance of PSCs.

Effect of fluorine substitution on properties of hole-transporting materials for perovskite solar cells

In photovoltaic technologies, hole-transporting materials (HTMs) play a critical role in realizing highly efficient performance of perovskite solar cells (PSCs). Herein, a series of fluorine substituted small molecules based on triphenylamine backbone are designed by controlling fluorine atoms number and position. A comprehensive study on the structural modification is carried out to reveal the effect of fluorine substitution of HTMs. The energy level alignment, reorganization energy and the charge-transport properties are explored based on Quantum-chemical calculations. It is found that all difluorinated molecules have lower HOMO levels, which indicates that perovskite solar cells with two fluorine substituted hole-transporting materials may have higher open-circuit voltages. Moreover, the UV–vis absorption spectra of the studied molecules are slightly red-shifted with the increase of fluorine atoms. To further understand the effect of fluorine substitution on the hole transport properties, the hole mobilities of all HTMs are evaluated quantitatively using the Marcus theory and Einstein relation. The calculated results show that difluorinated molecules TPB-m-2F exhibit relatively higher hole mobility owing to efficient intermolecular interactions. As for monofluorinated molecules TPB-1F-a and TPB-1F-b, TPB-1F-a with fluorine atoms substituted on the inside position exhibit higher hole-transporting performance. Overall, we conclude that suitable modification of fluorine substitution is expected to improve the electrochemical and hole transport property of HTMs. We hope our theoretical investigation provide useful information for further improving the photovoltaic performance of PSCs.