HOMO Energy Levels Research Articles

Suzuki-Miyaura coupling reaction: Blue-yellow emitting AIE active dyes for organic electronics

A series of eight novel donor‒acceptor (D─A) based 2,3-di(thiophen-2-yl)quinoxaline derivatives 2–9 were prepared by modulating donor species on quinoxaline core with Palladium catalyzed Suzuki–Miyaura ‘C–C bond’ coupling reaction. The synthesized molecules were fully characterized and studied for impact of D–A interaction on opto-electrochemical properties. Absorption spectra of 2–9 display intramolecular charge transfer (ICT) transitions in the range of 388–414 nm. Dyes shows positive solvatochromism and emit in blue‒yellow region with emission maxima 444−550 nm on excitation at their respective ICT maxima in toluene, chloroform, DCM, DMSO and neat solid film. Further, solid state emission was studied for aggregation‒induced emission (AIE) effect in THF–water system due to the nanoparticles formation, as confirmed by FEG‒SEM technique. The HOMO and LUMO energy level for compounds 2–9 were measured by cyclic voltammetry and found in the range of −5.15 to −5.94 eV and −2.81 to −3.39 eV. Theoretical studies of molecules were also carried out by using DFT and TD‒DFT calculations. The comparable HOMO and LUMO energy levels with reported ambipolar materials and efficient solid-state emission make synthesized compounds potential candidate for solid state emissive, ambipolar charge transporting materials in organic electronics.

Effects of fluorine atom numbers on electrochromic properties of the benzothiadiazole-based D-A polymers

In this work, two fluorinated D-π-A-π-D type monomers, F-EDOT and FF-EDOT, were facilely synthesized by donor-acceptor-donor method via Stille coupling reaction, with monofluorinated benzothiadiazole and difluorinated benzothiadiazole as the acceptor units and 3,4-ethylenedioxythiophene (EDOT) as the donor units. The electrochemical polymerization behavior of the fluorinated monomers, electrochemical and electrochromic properties of the corresponding fluorinated D-A polymers were compared to study the effects of different fluorine atom numbers on the optoelectronic properties of the monomers and their resultant D-A polymers. The results show that the introduction of more F atoms into the conjugated backbone increases the oxidation potential of monomers, both of them have low initial oxidation potential (0.65 V/0.70 V). As in the case of monomers, the substitution of more F atoms also leads to the decreased HOMO energy level of the polymers, thus leading to the increased band gap energy of P(FF-EDOT) (1.39 eV). This result can be attributed to the deviation of planarity and the reduced effective conjugate length. As prepared fluorinated D-A polymers also have good adhesion on the electrode surface, favorable redox activity, and outstanding redox stability (the redox activity of P(F-EDOT) remains 99 % after 1000 cycles). At the same time, the fluorinated D-A polymers also show distinguish electrochromic properties under various external potentials; both the optical contrast and coloration efficiency decreased with the increase of F atom numbers, and the corresponding response time increased. As a result, both the fluorinated D-A polymers show light green in the neutral state, P(F-EDOT) shows more obvious electrochromic performance in the near infrared region (optical contrast: 35.02 %, coloration efficiency: 159.94 cm2 C−1, and quick response time: 0.2 s), accompanied with excellent discoloration stability and optical memory effect. The study of novel fluorinated-based electrochromic materials further expands the selection of acceptor units and the application prospect of electrochromic materials.

Preparation of novel fluorinated highly branched (A3 + B3)‐type hyperbranched poly(amide‐imides) for electrochromism and iodine adsorption

AbstractIn this study, a series of (A3 + B3)‐type fluorinated hyperbranched poly(amide‐imides) were successfully synthesized with carbazole and fluorene units as end‐capping moieties. All synthesized end‐capping hyperbranched PAIs showed over 70% branching as determined by 1H NMR, demonstrating good solubility and thermal stability (Tgs: 242–263°C, T10%: 576–629°C). The HOMO and LUMO energy levels of hyperbranched PAI films were measured at 4.65–4.73 and 1.51–1.66 eV, respectively, suggesting favorable reoxidation and reduction characteristics. PAI‐2 demonstrates a 46.6% transmittance variation (∆T, 418 nm), along with a coloring/bleaching process time of 2.3 s/1.6 s, a coloring efficiency (CE) of 310 cm2/C, and exceptional redox stability over 100 cycles. Furthermore, the synthesized PAIs containing electron‐withdrawing groups exhibited a high iodine adsorption capacity as determined by iodine adsorption tests (PAI‐1: 534 mg/g, PAI‐2: 579 mg/g, PAI‐3: 490 mg/g).

Synthesis, characterization, photophysical and electrochemical properties of new thiadiazole-based olefins for OLED applications

A three–step synthetic approach was employed to synthesize new thiadiazole-based olefins integrating customized functional groups. This methodology consistently delivered satisfactory overall yields ranging from 44 % to 57 %. Comprehensive structural characterization of the synthesized compounds was conducted using FT–IR and NMR (1H, 13C) spectroscopic techniques. The resulting thiadiazole-based olefins exhibited notable UV absorption (λmax = 309–382 nm). Among these, one compound displayed a green emission, while others exhibited red-orange emission, indicating a Stokes shift ranging from 5423 to 6835 cm–1. Their electrochemical behavior was analyzed, revealing an irreversible redox-active response and experimentally determined HOMO and LUMO energy levels indicated an electrochemical gap of <2.32 eV. Our comprehensive investigation, integrating experimental and theoretical methodologies with TD–DFT calculations, aimed to deepen the understanding of the photophysical properties of the target compounds. This comparative analysis between computational results and experimental data highlights the potential of these N-heteroaromatic compounds as organic small-molecule fluorophores for applications in electroluminescent devices.

Tailoring Diversified Peripheral Anchor Groups in Spirofluorene‐Dithiolane‐Based Hole Transporting Materials for Efficient Organic and Perovskite Solar Cells from First‐Principle

AbstractThis quantum mechanical approach recommends push–pull molecular engineering to fabricate hole‐transporting materials (HTMs) for photovoltaic cells. It integrates acceptor moieties via thiophene to fluorene core, resulting in five novel HTMs (SFD‐1 to SFD‐5). The results exhibit that derivative HTMs show excellent coherence in excitation, dispersion, and transportation of charge carriers, ensuring robust hole mobility. The anchor moieties functionalized HTMs unveil excellent band alignment with perovskite with fitting HOMO energy levels (−4.93–−5.35 eV), less optical absorption in visible portion ( &lt; 520). This acceptor integration has improved the hole mobility in derivatives, accredited to the smaller hole reorganization energy (0.14–0.68 eV), and greater hole transfer integral (0.22–0.33 eV). The transition density matrix analysis exhibited robust electronic coupling, subtler charge carrier overlapping and greater charge transfer length (7.48–13.73 Å). This resulted in an excellent upsurge in intrinsic charge transference (70.75–92.70%) and smaller exciton binding energy, leading to easier exciton dissociation, and fewer recombination fatalities. However, an adequate variation in dipole moment (4.04 D to 16.34 D) and Gibbs solvation‐free energy (−18.06 to −21.89 kcal mol−1) ensures facile film formation and processability. In conclusion, this approach recommends these flourene‐based HTMs are highly desireable for forthcoming solar cell technology.

Microscopic insights into effects of sulfolane additive on Li–S battery electrolyte

Lithium–sulfur (Li–S) batteries, which have a high theoretical capacity and can be prepared using low-cost activation materials, are a promising alternative for realizing high-energy-density battery systems. However, the stability of the electrolyte and the shuttle effect caused by dissolved lithium polysulfides in the electrolyte prevent their practical application. Due to its non-flammability and high oxidation stability, sulfolane shows good promise for improving the oxidation stability and weakening the shuttle effect of Li–S electrolytes. In this work, the effects of a sulfolane additive on a Li–S battery electrolyte were revealed by density functional theory calculations and molecular dynamics simulations. The molecular orbitals, thermodynamics, and dynamics of the oxidation reaction were analyzed from the electron level. The addition of sulfolane lowers the HOMO energy level and the configuration energy difference, which leads to improved oxidation stability. Furthermore, sulfolane shows affinity to the S atoms close to Li, which correspond to low-order polysulfides. This affinity is confirmed by binding energy data and indicates that the addition of sulfolane inhibits the diffusion of Li2S4, Li2S6 and Li2S8. This work provides an analysis of the effects of sulfolane as an additive from the electron and molecular levels, which will promote a better understanding of Li–S battery systems and enable the design of improved electrolytes.

Construction frontier molecular orbital prediction model with transfer learning for organic materials

The frontier molecular orbitals of organic semiconductor materials play a crucial role in the performance of photoelectric devices, including organic photovoltaics (OPVs), organic light-emitting diodes (OLEDs), and organic photodetectors (OPDs). In this work, a model for predicting frontier molecular orbital of organic materials, including HOMO and LUMO levels, is established with the extreme gradient boosting algorithm and Klekota-Roth fingerprints. The correlation coefficients of HOMO or LUMO energy levels in the testing set are 0.75 and 0.84 in the transfer model from 11,626 DFT data in Harvard Energy database to 1198 experimental data in literature. The difference between the ML predicted value and the experimental value is smaller than the difference between ML prediction and DFT calculation, always less than 10%. Moreover, based on correlation and SHAP interpretability analysis, 13 key structural fragments influencing energy levels are selected to further verify the effective regulation of the frontier molecular orbital by the key structural fragments in practical applications. Considering the completely opposite regulatory functions of key structural fragments on HOMO and LUMO energy levels, four new Y6 derivatives, Y-PCP, Y-P6F, Y-PCF, and Y-P4FC, are designed to flexibly modify the HOMO and LUMO energy levels. The prediction trends of ML align closely with the computational trends from DFT. It is worth noting that the accuracy of LUMO energy level prediction by the prediction model makes up for the instability of DFT calculation on LUMO energy level. This work offers a cost-effective method to accelerate the acquisition of electronic properties of organic materials.

Thieno[3,2-b]thiophene flanked para-azaquinodimethane π-extended aromatic-quinoidal polymers

A series of thieno[3,2-b]thiophene (TT) flanked para-azaquinodimethane (p-AQM) based quinoidal conjugated polymers PAQM2TT-T, PAQM2TT-BT and PAQM3TT were designed in a strategy to extend the aromatic-quinoidal π-system. The three polymers were synthesized by Stille polycondensation, and their opto-electronic properties and device performance in field-effect transistors have been explored. From absorption spectroscopy, the polymers show low bandgaps (1.54–1.57 eV) and high HOMO energy levels. They exhibit typical p-type behavior according to the results of the characterization of the field-effect transistors with average charge carrier mobilities of 0.08 cm2 V−1 s−1 for PAQM2TT-T, 0.12 cm2 V−1 s−1 for PAQM2TT-BT and 0.05 cm2 V−1 s−1 for PAM3TT. This report presents an alternative π-extended quinoidal-donor strategy to control the molecular design and properties of new p-AQM-based conjugated polymers.

Implications for electronic structures of S-doped graphene nanoribbons from a DFTB algorithm at atomic scale

Self-consistent charge density functional tight binding simulations were used to provide implications for the effect of S atoms’ doping on geometrical structures and electronic states in armchair graphene nanoribbons with different widths. The geometric configurations, energy, charge density differences, Mulliken charges, and molecular orbitals at HOMO and LUMO energy levels are characterized. Besides the changes of bond length and bond angles, the calculation results indicate that the band structures and bandgaps of the graphene nanoribbons is affected by the nanoribbon width as well as S doping positions, where the ribbons exhibit metallic or semiconductor properties. Doping S atoms result significant changes in the charge density differences and Mulliken charges on the atoms near the doped atom. At the same time, the HOMOs and LUMOs also present differences.

Theoretical Investigation of the Effects of Aldehyde Substitution with Pyran Groups in D-π-A Dye on Performance of DSSCs.

This work investigated the substitution of the aldehyde with a pyran functional group in D-π-aldehyde dye to improve cell performance. This strategy was suggested by recent work that synthesized D-π-aldehyde dye, which achieved a maximum absorption wavelength that was only slightly off the threshold for an ideal sensitizer. Therefore, DFT and TD-DFT were used to investigate the effect of different pyran substituents to replace the aldehyde group. The pyran groups reduced the dye energy gap better than other known anchoring groups. The proposed dyes showed facile intermolecular charge transfer through the localization of HOMO and LUMO orbitals on the donor and acceptor parts, which promoted orbital overlap with the TiO2 surface. The studied dyes have HOMO and LOMO energy levels that could regenerate electrons from redox potential electrodes and inject electrons into the TiO2 conduction band. The lone pairs of oxygen atoms in pyran components act as nucleophile centers, facilitating adsorption on the TiO2 surface through their electrophile atoms. Pyrans increased the efficacy of dye sensitizers by extending their absorbance range and causing the maximum peak to redshift deeper into the visible region. The effects of the pyran groups on photovoltaic properties such as light harvesting efficiency (LHE), free energy change of electron injection, and dye regeneration were investigated and discussed. The adsorption behaviors of the proposed dyes on the TiO2 (1 1 0) surface were investigated by means of Monte Carlo simulations. The calculated adsorption energies indicates that pyran fragments, compared to the aldehyde in the main dye, had a greater ability to induce the adsorption onto the TiO2 substrate.

The superiority of isomeric, fluorination and curtailed π-conjunction on A–D–A type acceptors for organic photovoltaics

The performance of organic solar cell (OSC) devices has been significantly enhanced by the dramatic evolution of A–D–A type non-fullerene acceptors (NFAs). Nevertheless, the structure–property-performance relationship of NFAs in the OSC device is unclear. Here, the intrinsic design factors of isomeric, fluorination and π-conjunction curtailing on the photophysical properties of benzodi (thienopyran) (BDTP) (named NBDTP-M, NBDTTP-M, NBDTP-Fin, and NBDTP-Fout)-based NFAs are discussed. The results show that fluorination on the terminal group of NBDTP-Fout could effectively decrease the highest occupied orbital (HOMO) energy level and the lowest unoccupied orbital (LUMO) energy level. And the long π-conjugated donor unit for NBDTTP-M could increase the HOMO energy level and bring a small HOMO-LUMO energy bandgap. Meanwhile, the substitution of external oxygen atoms and the fluorine atoms in the terminal group could introduce positive changes to the electrostatic potential of the NBDTP-Fout, favouring the charge separation at the donor/acceptor interface. Moreover, the structural design of external oxygen atom substitution, fluorination on the terminal group and curtailed π-conjugated donor unit could decrease the electron vibration-coupling of exciton diffusion, exciton dissociation and electronic transfer processes. The suppression of the exciton decay and charge recombination in those high-performance NFAs indicate that the investigated molecular designs could be effective for further improvement of OSCs.

Theoretical exploration of the photophysical properties of two series of iridium(III) complexes with different main ligand

On the basis of the thiophene-containing and furan-containing complexes, we design four complexes by introducing thiazole, isothiazole, oxazole, isoxazole on main ligands. The electronic structure, absorption and emission spectra, charge injection/transport properties, absorption and phosphorescence properties have been investigated by density functional theory (DFT) and time-dependent density functional theory (TDDFT). Introducing S atom to substitute O atom could enhance HOMO energy level, blueshift emission wavelength, decrease ΔES1- T1 value. The introduction of N atom on furan ring and thiophene ring could decrease HOMO and LUMO energy levels and energy gaps, blueshift emission wavelength, decrease ΔES1- T1 value, enhance electron transport ability. Introducing thiazole could decrease hole injection ability and ΔES1- T1, and then may have higher ΦPL. Isoxazole and isothiazole groups could facilitate the electron transition from HOMO to LUMO and enhance hole injection ability. Thiazole and isothiazole groups could increase absorption peak strength and hole transport ability.

Novel low‐band gap non‐fullerene acceptors based on IDIC core as potential photovoltaic materials

AbstractThree novel non‐fullerene acceptors (NFAs) (PhBu‐IDT‐BT‐IC, PhBu‐IDT‐BT‐IC4F and PhBu‐IDT‐BT‐IC4Cl) based on 3,8‐dioctyl‐indaceno[1,2‐b:5,6‐b’]dithiophene (IDT) core have been designed and synthesized with and without halogen (F and Cl) substitution. The NFAs showed high thermal stability. The ultraviolet–visible absorption studies in solution and thin film for the three acceptors revealed maximum absorption from 687 to 732 nm and 731 to 847 nm, respectively. The onset of absorption in the thin film was found to be extending up to around 960 nm for PhBu‐IDT‐BT‐IC4Cl. The optical band gap ranged from 1.30 to 1.41 eV, which are very low and useful for photovoltaic application. The introduction of halogen appreciably altered the LUMO energy levels, whereas the HOMO energy levels were nearly intact. These small molecule non‐fullerene acceptors could be used as potential acceptors in bulk heterojunction organic photovoltaic (BHJ‐OPV) applications.

Tunable optoelectronic performances of aminated benzothiadiazole-based D-A-D conjugated electrochromic polymers

Introducing heteroatom groups into benzothiadiazole (BT) unit has proven to be a very effective way to improve the optoelectronic properties of conjugate polymer due to its comprehensive advantages of lowering the HOMO or LUMO energy level, and increasing the interaction force on the polymer backbone. However, at present, little attention was paid to introducing amino groups into the BT unit. Herein, in this work, three D-A-D type aminated monomers (Th–NH2-BT, Th–2NH2-BT, and EDOT-2NH2-BT) with aminated benzothiadiazole as the acceptor unit and thiophene or 3,4-ethylenedioxythiophene (EDOT) as the donor unit were successfully synthesized by Stille coupling reaction, and their corresponding aminated polymers (P(Th–NH2-BT), P(Th–2NH2-BT), and P(EDOT-2NH2-BT)) were facilely achieved by electrochemical polymerization method. The optoelectronic properties of the aminated monomers and their D-A polymers were carefully analyzed, and the electrochemical and electrochromic properties of the resultant aminated polymers were further studied. The finally results show that the absorption and fluorescence spectra of Th–2NH2-BT and EDOT-2NH2-BT are both blue-shifted compared to Th–NH2-BT, and the corresponding optical bandgap are gradually increased (2.41 eV–2.65 eV). EDOT-2NH2-BT has a relatively lower oxidation potential (0.73 V) and P(EDOT-2NH2-BT) also has a wide potential window and better redox stability, which was very beneficial for improving its resultant D-A aminated polymers’ optoelectronic properties. As a result, as-formed P(EDOT-2NH2-BT) shown obvious color change from green in the neutral state to gray in the oxidized state with favorable electrochromic performances, with a high optical contrast (ΔT = 17.17 % at 860 nm) and high coloration efficiency (CE = 223 C−1 cm2 at 860 nm), so it is one of the promising materials that can be used in electrochromic devices.

Molecular engineering push-pull structural versatility in the triphenylamine-thienodioxine-based hole transporting materials for high-performance organic and perovskite solar cells

This study proposes a push-pull molecular engineering approach to fabricate versatile hole-transporting materials (HTMs) for photovoltaic cells. Herein, we introduce a D-π-A strategy for fabricating four highly functional small molecules of thienodioxine core-based HTMs (CJ06C1 to CJ06C4), via core functionalization with diversified electron-withdrawing acceptor moieties. The engineered HTMs are evaluated by employing quantum calculations to analyze the structure-property relationships from optoelectronic, electrochemical, and solvability attributes. The findings reveal that acceptor-integrated HTMs unveil excellent band alignment with active perovskite layer with deeper HOMO energy levels (-4.96 eV to 5.02 eV), transparency in the visible portion λmaxabs<521, which entail appropriate photophysical attributes. In comparison to the reference HTM (CJ06), the acceptor-integrated HTMs have exhibited potentially higher hole mobility rate, accredited to smaller hole reorganization energies (0.15 eV to 0.21 eV), greater transfer integral values (0.26 eV to 0.31 eV) and greater hole hopping rates (1.08×1028 S−1 to 3.70×1028 S−1). The electron-excitation investigation exhibited stronger electronic coupling, smaller hole-electron spatial overlapping, and higher charge transference length (19.42 Å to 21.14 Å) in the fabricated HTMs. Thus ensued a significant upsurge in intrinsic charge transference (74.22–99.74 %) and lower exciton binding energies, leading to easy charge dissociation and low recombination chances compared to the parent HTM (CJ06C1). Moreover, the findings from dipole moments (12.56 D to 13.05 D) and solvation-free energy (-91.08 kJ/mol) to −108.1 kJ/mol),imply easier processability and aptness for film formation. Overall, this study ensures the efficiency of thienodioxine core functionalization with acceptor moieties for fabricating state-of-the-art HTMs. The promising attributes of fabricated HTMs pave the way for forthcoming perovskite solar cells.

Effect of methyl trifluoride substitution on colorless transparency of polyimide: A DFT/TD-DFT study

The rapid advancement of flexible electronic devices has rendered high-performance colorless transparency polyimide (PI) films essential for energy storage and devices. However, there still remains controversy regarding the charge-transfer complexes in relation to the optical properties of PIs. Herein, we employed a combination of DFT and TD-DFT methods to elucidate the hole and electron characteristics of PIs. The results revealed that the incorporation of a CF3 group significantly enhances the dipole moment. Notably, the incorporation of CF3 groups onto both the anhydride and diamine units impedes charge transfer, resulting in a reduction of the HOMO energy level and an increse of the LUMO energy. The calculation results also indicate that the introduction of CF3 groups markedly hinders charge transfer within P4 in its excited state, leading to the minimum values for three characteristic parameters (D = 2.60 Å, CT = 0.51 e, t = 0.53 Å). Therefore, P4 exhibits a shortest charge transfer pathway resulting in minimal electron transfer and obvious blue-shifted UV–vis spectra, thus contributing to its excellent colorless transparency. This work provides a theoretical foundation and guidance for targeted design and development of colorless transparent PI films.

Synthesis, enantiomeric separation and (chir)optical properties of [7]helicene derivatives for OLED applications. A comprehensive experimental and computational investigation

A two–step photochemical process was employed to synthesize new racemic [7]helicenes with appropriate functional groups, resulting in an overall yield of 61 % to 74 %. These helical species showed good solubility in common solvents and confirmed structurally through various spectroscopic methods. In solution, they exhibited strong absorption (λabs = 250–500 nm) and blue light emission with a fluorescence quantum yield (Φ) ranging from 7 % to 26 %. Experimental analysis of their HOMO and LUMO energy levels highlighted an irreversible electrochemical behavior and a band gap (Eg–el) of 2.60 eV to 2.64 eV. The helicenes were successfully separated by chiral HPLC, yielding P and M–enantiomers in high optical purity (>98.5 % up to >99.5 % ee) that demonstrated substantial optical rotations (e.g., +3700–5000 for the P–enantiomer at λ = 589 nm) and notable electronic circular dichroism (ECD) signals. Density functional theory (DFT) was undertaken to establish connections between diverse structure-properties relationships and precisely replicate the experimental findings. Ultimately, these helical species, with notable performance in emission, electrochemical behavior, and thermal stability, can effectively serve as blue-emitting chiral dopants in OLED devices and as hole-transport units.

Disulfide bonded polyimide cathode of rechargeable magnesium batteries: Improved capacity via reversible break/formation of disulfide and sulfur-oxygen bonds

Rechargeable magnesium batteries are a potential selection for large-scale energy storage technologies, but development of cathode materials is the major difficulty at present. Organic polyimides are promising magnesium battery cathodes with the open and amorphous frameworks as well as enhanced charge delocalization. However, only two carbonyls are redox-active out of four for each imide unit, which largely limits the capacity. Herein, a new polyimide containing disulfide bond is fabricated and studied as cathode for rechargeable magnesium batteries. This polyimide shows a high capacity beyond the traditional two-electron principle. A mechanism study demonstrates that carbonyl enolization and disulfide bond break/formation occur in the redox process, leading to formation/break of sulfur-oxygen bond. This sulfur-oxygen bond enhances enolization and electron delocalization, resulting in an improved capacity. Further theoretical computation indicates a charge transfer within this sulfur-oxygen bond. The two-electron reduction state exhibits quite low HOMO and LUMO energy levels, which makes the disulfide bonded polyimide have a higher tendency to accept more electrons and a higher oxidation stability after reduction.

Elucidating roles of fulleropyrrolidine-based materials as extraordinary electron transporters for boosting efficiency of perovskite photovoltaics

To achieve an ideal electron transfer layer (ETL) for perovskite solar cell (PSC), effective compounds were developed based on fullerene C60 functionalized with a pyrrolidine ring (fulleropyrrolidine), to which a cyanoethyl group, a thiophene ring, and four DNA bases were attached. Density functional theory (DFT) calculations were employed to study structural, electronic, optical, and electron mobility features of these materials. To more precisely determine the HOMO and LUMO energy levels of all samples, the NBO calculations were accomplished at PBE0-D3/6-31G(d,p) theoretical level. The LUMO levels of all ETL samples could be aligned with the conduction band of perovskite CsFAMAPbIBr via their coupling within fabricated PSCs, enabling easy electron injection from CsFAMAPbIBr to the Ag electrode. All functionalized fullerene C60–based ETLs exhibited very high electron mobilities in the range of 0.744–1.598 cm2V−1s−1 which were significantly greater than 1.461 × 10−5 cm2V−1s−1 for pure C60 as the reference. High fill factors (FFs), power conversion efficiencies (PCEs), and open circuit voltages (VOC) were measured for PSC devices with C60–based ETLs, varying within the ranges of 0.892–0.897, 22.489–23.984 %, and 1.111–1.179 V, respectively, indicating they could yield excellent photovoltaic parameters.

Enhancing Efficiency and Durability of Perovskite Solar Cells with Chlorine‐Functionalized Fully Conjugated Porous Aromatic Framework

Non‐radiative recombination, caused by trap states, significantly hampers the efficiency and stability of perovskite solar cells (PSCs). The emerging porous organic polymers (POPs) show promise as a platform for designing novel defect passivation agents due to their rigid and porous structure. However, the POPs reported so far lack either sufficient stability or clear sites of interactions with the defects. Herein, two chlorine‐functionalized, fully conjugated porous aromatic frameworks (PAFs) were constructed via a decarbonylation reaction. The chlorinated PAFs feature unique long‐range conjugated networks bearing multiple chlorine atoms, significantly improving the photovoltaic performance and stability of doped solar cells. Combined experimental and theoretical analyses confirmed the strong passivation effects of conjugated structure to the defect through Cl sites. Specifically, PAF‐159, bearing a triphenylamine moiety, demonstrated stronger Cl‐Pb bonding and higher passivation efficiency due to the presence of π* anti‐bonding orbitals, which elevate the HOMO energy level and facilitate Cl‐Pb charge transfer. Consequently, we obtained high‐performance PAF‐159‐doped devices with advanced PCE (24.3%), good storage stability (retaining 86% after 3000 hours), and good long‐term operational stability (retaining 92% after 350 hours)