Charge Transfer Energy Research Articles

Mn doped CoFe layered double hydroxides lead to d-d orbital repulsion toward advanced electrocatalysts for oxygen evolution reaction

Currently, developing highly active and low-cost electrocatalytic materials for oxygen evolution reaction (OER) is an enormously grand challenge. Herein, we developed a novel and highly active Mn doped Co2Fe layer double hydroxide (LDH) electrocatalyst for OER. We discovered that these electrocatalytic materials can be directly grown on carbon papers to construct high-specific-surface-area electrode, which shows the lowest overpotential of 266 mV at 10 mA cm−2. Furthermore, after introducing Mn element, DFT + U calculation found that the ∗OOH of Fe-site on Co2Fe0.67Mn0.33 LDH could draw more electrons than Co2Fe LDH due to the electronegativity differences between Fe-site on Co2Fe0.67Mn0.33 LDH and Fe-site on Co2Fe LDH, which is reason that the energy level of Fe 3d (eg) was obviously downshifted by d-d repulsion of Mn 3d and Fe 3d in the neighboring sites of Co2Fe0.67Mn0.33 LDH after doped Mn element, which leads to reduce charge-transfer energy from O 2p to Fe 3d (eg) to promote oxygen evolution processes for OER. Meanwhile, the band gap is also decreased after doped Mn element in Co2Fe LDH due to the downshifted eg orbital energy of Fe 3d. This study gives a general avenue to design and developing efficiently active LDH electrocatalysts for OER in the future.

Hierarchical MoN@NiFe-LDH Heterostructure Nanowire Array for Highly Efficient Electrocatalytic Hydrogen Evolution.

The slow charge transfer and high energy barrier are the key restrictions of cost-effective electrocatalysts for hydrogen production. A hierarchical heterostructure of MoN@NiFe-layered double hydroxides (LDH) is developed, with NiFe-LDH nanosheets supported on MoN nanowire arrays. The as-prepared MoN@NiFe-LDH exhibits a remarkably high performance on hydrogen production in alkaline medium, which is close to the benchmark Pt/C. The theoretical computations indicate that MoN@NiFe-LDH has a metallic character inherited from MoN, which gives rise to the promoted charge transfer. Furthermore, the adsorption intensity of intermediates on MoN@NiFe-LDH is optimized and thereby the energy barrier is diminished. This work demonstrates the significance of constructing heterostructure for boosting the charge transfer and reducing the energy barrier, which can shed light on the development of highly efficient and low-cost electrocatalyst for hydrogen production.

Charge Distribution across Capped and Uncapped Infinite-Layer Neodymium Nickelate Thin Films.

Charge ordering (CO) phenomena have been widely debated in strongly-correlated electron systems mainly regarding their role in high-temperature superconductivity. Here, the structural and charge distribution in NdNiO2 thin films prepared with and without capping layers, and characterized by the absence and presence of CO are elucidated. The microstructural and spectroscopic analysis is done by scanning transmission electron microscopy-electron energy loss spectroscopy (STEM-EELS) and hard X-ray photoemission spectroscopy (HAXPES). Capped samples show Ni1+ , with an out-of-plane (o-o-p) lattice parameter of around 3.30 Å indicating good stabilization of the infinite-layer structure. Bulk-sensitive HAXPES on Ni-2p shows weak satellite features indicating large charge-transfer energy. The uncapped samples evidence an increase of the o-o-p parameter up to 3.65 Å on the thin film top with a valence toward Ni2+ in this region. Here, 4D-STEM demonstrates (303)-oriented stripes which emerge from partially occupied apical oxygen. Those stripes form quasi-2D coherent domains viewed as rods in the reciprocal space with Δqz ≈ 0.24 reciprocal lattice units (r.l.u.) extension located at Q = ( ) and ( ) r.l.u. The stripes associated with oxygen re-intercalation concomitant with hole doping suggest a possible link to the previously reported CO in infinite-layer nickelate thin films.

Thickness dependent OER electrocatalysis of epitaxial thin film of high entropy oxide

High entropy oxides (HEOs), which contain multiple elements in the same crystallographic site, are a promising platform for electrocatalysis in oxygen evolution reaction (OER). Investigating these materials in epitaxial thin film form expands the possibility of tuning OER activity by several means, which are not realizable in polycrystalline samples. To date, very few such studies have been reported. In this work, the OER activity of single-crystalline thin films of (La0.2Pr0.2Nd0.2Sm0.2Eu0.2)NiO3, grown on NdGaO3 substrates have been investigated in 0.1 M KOH electrolyte as a function of film thickness. The OER activity increases with the thickness of the film. X-ray absorption spectroscopy measurements find an increase in Ni d-O p covalency and a decrease in charge transfer energy with the increase in film thickness. These facilitate higher charge transfer between Ni and surface adsorbates, increasing OER activity. However, the OER process leads to excessive leaching of thicker films and the OER activity of a 75 unit cell thick film is found to be optimal in the present study. This work demonstrates that the thickness of perovskite oxides can be used as a parameter to enhance OER activity.

The ability of twisted nanographene for removal of Pb2+, Hg2+ and Cd2+ ions from wastewater: Computational study.

Heavy metal ion removal from wastewater has become a global concern due to its extensive negative effects on human health and the environment. The density functional theory is employed to investigate the possibility of removing Pb2+, Hg2+, and Cd2+ ions from wastewater using nano-graphene. Researchers have shown that NG can efficiently remove heavy metals from media. Additionally, it was shown that the adsorption of Pb2+, Hg2+, and Cd2+ ions might reduce the large pristine NG (HOMO-LUMO) gap. HSE06 may accurately represent NG electrical characteristics. The DFT-D3 method was also used to account for Van der Waals interactions in the present study. The results demonstrated that charge transfer and binding energy remained greater in cation-NG systems with greater electron transfer rates. Pb2+, Hg2+, and Cd2+ adsorption results indicated that Egap was significantly reduced by 68%, 15%, and 21%, respectively. The Pb2+@NG complex exhibited the strongest oscillator strength. This may be explained by the enormous occupation number difference between the 2px orbital of the C atoms and the 6s orbital of the Pb2+ cations. The greater Ebin value of Pb2+@NG is consistent with the increased predicted redshifts (199nm). DFT (hybrid functional HSE06) studies that rely on time showed that the relevant complexes have "ligand-to-metal charge transfer" excitations. In general, it was found that Pb2+@NG had the greatest k value, binding energy, redshifts, and charge transfer rate among the complexes. The theoretical insights of this study may influence experimental efforts to identify NG-based compounds that are effective and efficient at removing pollutants from wastewater.

Structure, chemical reactivity, NBO, MEP analysis and thermodynamic parameters of pentamethyl benzene using DFT study

This study explores the structural, molecular and electronic properties of the pentamethyl benzene (PMB) using quantum chemical calculations employing DFT/ B3LYP/6–311++G(d,p) level of theory. Structural parameters, HOMO-LUMO energies, chemical reactivity descriptors and molecular electrostatic potential (MEP) were evaluated from the optimized molecular geometry. The computed small band gap energy, correlated with the UV–visible spectrum, demonstrates that the test molecule has good biological activity. NLO activity of the molecule was also studied by evaluating dipole moment and first order hyperpolarizability values. Intra-molecular charge transfer, donor-acceptor transitions and stabilizations energies were determined from the analyses of natural bond orbital (NBO) and natural population. 1H and 13C chemical shifts were computed from the simulated NMR spectrum following GIAO approach in DMSO‑d6 solvent at the same level of DFT. Furthermore, thermodynamic parameters and rotational constants were also calculated for this molecule.

On the Role of Charge Transfer in Many-Body Non-Covalent Interactions.

Charge transfer is one of the mechanisms involved in non-covalent interactions. In molecular dimers, its contribution to pairwise interaction energies has been studied extensively using a variety of interaction energy decomposition schemes. In polar interactions such as hydrogen bonds, it can contribute ten or several tens of percent of the interaction energy. Less is known about its importance in higher-order interactions in many-body systems, mainly because of the lack of methods applicable to this problem. In this work, we extend our method for the quantification of the charge-transfer energy based on constrained DFT to many-body cases and apply it to model trimers extracted from molecular crystals. Our calculations show that charge transfer can account for a large fraction of the total three-body interaction energy. This also has implications for DFT calculations of many-body interactions in general as it is known that many DFT functionals struggle to describe charge-transfer effects correctly.

Engineering push–pull structural versatility in highly functional carbazole-based hole transporting materials design for efficient perovskites solar devices

This study proposes a push–pull molecular engineering strategy to design highly functional hole transport materials (HTMs) for perovskite solar cells (PSCs). The strategy involves introducing acceptor-anchor groups via benzene spacer to the versatile carbazole core containing dimethoxytriphenylamine side groups, resulting in a series of nine newly designed HTM moieties (BEN-A1 to BEN-A9). Quantum simulation protocols using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods were employed to investigate the designed HTMs. Our results demonstrate that the designed HTMs exhibit promising charge separation and transport throughout the molecule with lower spatial hole-electron overlap at the carbazole core, resulting in 98% intrinsic charge transfer and small exciton binding energy (0.003–0.108 eV). The HTMs also exhibit stabilized HOMO energy levels (by up to 0.13 eV) approaching the threshold (−5.38 eV) with appropriate HTM/Perovskite energy levels alignment, suggesting excellent charge extraction and higher VOC. Optical analysis shows that our proposed HTMs exhibit large stokes shift values (82–108 nm) and transparent absorption in broader visible region, enabling full utilization of light for perovskite layer for photocurrent generation, efficient energy conversion, reduced thermalization losses, and improved spectral selectivity. The HTMs exhibit smaller hole reorganization energy (0.111–0.137 eV) and higher transfer integral, indicating robust hole mobility owing to enhanced carbazole core functionality. Furthermore, higher negative solvation-free energy values (−16.19 to −20.89 kcal/mol) and elevated dipole moments imply better solubility and surface-wetting properties. Overall, this study broadens our understanding of push–pull molecular engineering for versatile carbazole-based HTMs, which have immense prospects for efficient and functional application in PSCs.

Effect of different solvents, molecular level vibrational energies, electronic, electrostatic, donar-acceptor and pharmaceutical studies on 3-methoxy phenyl acetonitrile- anti depressant agent

The most economical method for analyzing molecular structure is density functional theory (DFT), which has several applications in the study of vibrational spectrum biological systems. In the context of biological in addition to NLO behavior, the density functional theory (DFT) technique has numerous purposes. It turned out to be the most financially sound approach for examining molecular geometry. 3-Methoxy phenyl acetonitrile (3MPAN) has been optimized and its skeletal parameters were computed using the basis function 6–311++ G(d,p). HOMO and LUMO analytics have been used to determine the transfer of charge within the molecule. By detecting internal charge transfer, hyperconjugation, and stabilization energy, the NBO research has been used to confirm the molecule's stability. Mulliken's charges and molecular electrostatic potential were thoroughly investigated utilizing DFT techniques. B3LYP basis functionals were used to look at the NLO properties of the drug molecule. Condensed Fukui functions and global descriptors have been extensively used to study the reactive sites and reactivity of the pharmacological molecule. 29.85 Kcal/mol equilibrium energy is the greatest one occurred between O1 of LP(2) to π*(C5-C8). In order to investigate solvation analysis, various solvents were used. Solvents drastically altered the molecule's global characteristics and structural reactivity. Compared to other sol-vents, methonal has the largest band gap value of 5.619 eV. The substance under study has extraordinary NLO (non-linear optical) characteristics. For both the gas phases and solvents, ELF, LOL and RDG were stimulated. Although and drug-likeness were used to support the bioactivities. The fact that this chemical adheres to five Lipinski's rule means therefore, ingesting effective dose of similar compounds should not pose an issue. The results of docking studies demonstrated the effectiveness of the ligand under research as an anti-depressant medication.

Electroactive site enriched battery-type worm-like cobalt tungstate nanoarchitecture electrode material for performance-enhanced hybrid supercapacitor

The supercapacitor performances of stable and highly efficient electrode materials crucially depend on their physicochemical parameters, which are influenced by the preparation conditions and techniques. Herein, the worm-like CoWO4 (CWO) nanoarchitecture is achieved through a facile hydrothermal method followed by pyrolysis. The effect of pyrolysis temperature on the physicochemical properties, such as crystallinity, surface area, porosity, particle size, and morphology of the prepared CWO nanomaterials, is examined. From these observations, the pyrolyzing temperature significantly impacts the physicochemical characteristics and the associated electrochemical performances. Further, the final product's crystallite size increases, and surface area concomitantly fall from 16 to 34 nm and 26.1–12.9 m2 g−1, respectively, as the pyrolyzing process is increased from 400 to 600 °C. The distinct morphological feature of worm-like CWO-A nanostructure pyrolyzed at 400 °C is advantageous to have effective charge transfer and large energy storage capacity. Markedly, the worm-like CWO-A electrode depicts a superior specific capacity of 445 and 284 C g−1 at 1 and 20 A g−1, respectively, suggesting an excellent rate performance. Moreover, the constructed hybrid supercapacitor (CWO-A//AC) attains a maximum energy density of 41.38 Wh kg−1 at a power density of 627.42 W kg−1 with an outstanding long-term cyclic retention and ∼9.3% of capacity loss for 10,000 cycles. Thus, this study highlights that the distinct worm-like CWO-A nanostructure could be a suitable electrode material for supercapacitor applications.

An ICT-FRET-based ratiometric fluorescent probe for hydrogen polysulfide based on a coumarin-naphthalimide derivative

Hydrogen polysulfide (H2Sn, n > 1), as one of the important members of reactive sulfur species (RSS), plays a vital part in the processes of both their physiology and pathology. In this work, a ratiometric fluorescent probe for H2Sn had been designed and prepared based on the combination mechanism of intramolecular charge transfer (ICT) and fluorescence resonance energy transfer (FRET). The probe chose a coumarin derivative as the energy donor, a naphthalimide derivative as the energy acceptor and 2-fluoro-5-nitrobenzoate as the H2Sn recognition group. When H2Sn was not present in the system, the ICT process of the naphthalimide acceptor was inhibited and the FRET process from the coumarin donor to the naphthalimide acceptor was turned off. When H2Sn was added, both ICT and FRET occurred due to the nucleophilic substitution-cyclization reactions between the probe and hydrogen polysulfide. In addition, the ratio value of the emission intensities at 550 nm and 473 nm (I550 nm/I473 nm) of this probe had a good linear relationship with H2Sn concentration in the range of 6.0 × 10-7-5.0 × 10-5 mol·L-1, and a detection limit of 1.8 × 10-7 mol·L-1 was obtained. The developed probe had high selectivity and sensitivity, as well as good biocompatibility. Additionally, the probe had been used to successfully image both indigenous and exogenous hydrogen polysulfide in A549 cells using confocal microscope.

Linear scaling of charge transfer versus work function of Ammonia chemisorption on X-metal (X = Ag, Au, Pd, and Pt) surface

Although the d-band center theory can efficiently describe the interaction between gas molecules and transition metal surfaces, the specific reaction process and detailed adsorption criteria remain unclear. Therefore, we systemically investigated the adsorption process and mechanism of Ammonia (NH3) molecules on transition metal (i.e., Ag, Au, Pd and Pt) surfaces using first-principles calculations. Results indicate that the NH3 molecule undergoes chemisorption on the Pt (111) surface with considerable charge transfer and adsorption energy, indicating that Pt metal is a promising NH3-sensitive material. Furthermore, the chemisorption primarily entails the highest-occupied molecular orbital (HOMO) of NH3, and the metal atoms conform perfectly to the principles of energy-level matching, wave function matching, and maximal orbital wave function overlap. Notably, a linear relationship exists between the charge transfer of NH3 and the work function of X-metal substrates. Our findings provide a feasible way to efficiently design NH3-sensitive materials for experiments.

Confining bulk molecular O2 by inhibiting charge transfer on surface anions toward stable redox electrochemistry in layered oxide cathodes

Molecular O2 has been clarified as an important O-oxidation model in anionic redox, the charge compensation provided by which pushes energy-density limits of layered oxide cathodes. However, how to confine the bulk-formed molecular O2 and retard its conversation to free gaseous O2 (↑), an origin of unstable redox electrochemistry, remains open questions. Here, we propose a strategy via tuning relative values of Mott–Hubbard U and charge-transfer energy Δ to suppress charge transfer on surface anions to confine the bulk molecular O2. Supported by theoretical calculations, Nb5+ without 4d electrons which can enable U < < Δ is selected as a charge-transfer insulator. The thus Nb5+-surface-tailored model compound Na0.67Fe0.5Mn0.5O2 shows an oxygen-redox-inactive surface and well-confined bulk molecular O2 as directly uncovered by soft X-ray absorption spectroscopy and 50 K-electron paramagnetic resonance results respectively. Meanwhile, a stable redox electrochemistry with enhanced cycling stability, inhibited voltage decay and eliminated P2-O2 phase transitions is observed because of the well-caged bulk O2. More broadly, this work presents a versatile access to stabilize the important O-oxidation model, enriching approaches of stabilizing the anionic redox electrochemistry.

Oxygen on-site Coulomb energy in Pr1.3−xLa0.7CexCuO4 and Bi2Sr2CaCu2O8+δ and its relation with Heisenberg exchange

We study the electronic structure of electron-doped Pr$_{1.3-x}$La$_{0.7}$Ce$_{x}$CuO$_{4}$ (PLCCO ; $T_{c}$ = 27 K, x = 0.1) and hole-doped Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi2212 ; $T_{c}$ = 90 K) cuprate superconductors using x-ray absorption spectroscopy (XAS) and resonant photoemission spectroscopy (Res-PES). From Res-PES across the O K-edge and Cu L-edge, we identify the O 2p and Cu 3d partial density of states (PDOS) and their correlation satellites which originate in two-hole Auger final states. Using the Cini-Sawatzky method, analysis of the experimental O 2p PDOS shows an oxygen on-site Coulomb energy for PLCCO to be $U_{p}$ = 3.3$\pm$0.5 eV and for Bi2212, $U_{p}$ = 5.6$\pm$0.5 eV, while the copper on-site Coulomb correlation energy, $U_{d}$ = 6.5$\pm$0.5 eV for Bi2212. The expression for the Heisenberg exchange interaction $J$ in terms of the electronic parameters $U_{d}$, $U_{p}$, charge-transfer energy $\Delta$ and Cu-O hopping $t_{pd}$ obtained from a simple Cu$_2$O cluster model is used to carry out an optimization analysis consistent with $J$ known from scattering experiments. The analysis also provides the effective one band on-site Coulomb correlation energy $\tilde{U}$ and the effective hopping $\tilde{t}$. PLCCO and Bi2212 are shown to exhibit very similar values of $\tilde{U}$/$\tilde{t}$ $\sim$9-10, confirming the strongly correlated nature of the singlet ground state in the effective one-band model for both the materials.

Occurrence Modes of Critical Metals (Li+ and Ge4+) in the Organic Molecular Structures of Coal: A Density Functional Theory Study.

To explore the mechanism of critical metal (Li+ and Ge4+) occurrence in the organic molecular structures of different rank coals, simulations were investigated using quantum chemical density functional theory. In this paper, Wender lignite, bituminous, and anthracite molecular models were used as organic molecular structures in coal. The electrostatic potential (ESP), frontier molecular orbitals, and Mulliken charges were used to identify adsorption sites in organic molecular structures. Mulliken charge, bond length, Mayer bond order (MBO), and adsorption energy values were used to estimate the binding conformation and strength between organic molecular structures and critical metals (Li+ and Ge4+). The results showed that the negative ESP, the highest occupied molecular orbitals, and negative Mulliken charges in the organic molecular structures were located at the O atom of oxygen functional groups and the aromatic structures, respectively, which were the active sites for critical metal adsorption. Mulliken charge transfer, bond length, MBO, and adsorption energy data suggested that the binding of Li+ with organic molecular structures was controlled by the carbonyl group (C=O), while the aromatic structures had less effect on the occurrence of Li+ in the organic molecular structures. The maximum adsorption energy value for binding Li+ with organic molecular structures was -742.16 kJ/mol. The Ge4+ ions not only showed strong binding ability with oxygen functional groups, but also Ge4+ formed thermodynamically stable half-sandwich complexes with aromatic structures. Therefore, the coal rank had little effect on the binding of Ge4+ with organic molecular structures. Moreover, the binding of Ge4+ with organic molecule structures was enhanced by the synergistic interactions of oxygen functional groups and aromatic structures. The adsorption energy values were up to -8511.43 kJ/mol. The adsorption of organic matter in coal to critical metals (Li+ and Ge4+) generated changes in the spatial configuration of the organic molecular structure, including local twisting of the organic molecular structure in lignite and bending of the aromatic structure in anthracite.

Fe−O−P bond in MIL-88A(Fe)/BOHP heterojunctions as a highway for rapid electron transfer to enhance photo-Fenton abatement of enrofloxacin

MIL-88A(Fe)/BOHP (MxBy) heterojunctions were firstly fabricated via a ball-milling method, which were adopted as catalysts to activate hydrogen peroxide (H2O2) with the aid of visible light illumination to build a heterogeneous photocatalysis-Fenton-like synergetic system. The catalytic degradation efficiency of enrofloxacin (ENR) (10 mg/L) in the optimal M3B7/Vis/H2O2 system reached nearly 100 % with appreciable mineralization ability. Experimental and theoretical results co-unraveled that the formation of interfacial Fe−O−P chemical bonds between MIL-88A(Fe) and BOHP effectively reduced the charge transfer energy barrier (59.41–26.69 eV) and migration distance (3.104–1.917 Å), allowing the photo-generated carriers to be efficiently separated in space and improving the activation efficiency of H2O2 for producing more active species. Impressively, the constructed M3B7/Vis/H2O2 system was a cost-optimal and green technology for antibiotic wastewater treatment based on Electrical Energy per Order (EE/O) concept, life cycle assessment (LCA) and quantitative structure–activity relationship (QSAR) analysis.

General Charge Transfer Dipole Model for AMOEBA-Like Force Fields.

The development of highly accurate force fields is always an importance aspect in molecular modeling. In this work, we introduce a general damping-based charge transfer dipole (D-CTD) model to describe the charge transfer energy and the corresponding charge flow for H, C, N, O, P, S, F, Cl, and Br elements in common bio-organic systems. Then, two effective schemes to evaluate the charge flow from the corresponding induced dipole moment between the interacting molecules were also proposed and discussed. The potential applicability of the D-CTD model in ion-containing systems was also demonstrated in a series of ion-water complexes including Li+, Na+, K+, Mg2+, Ca2+, Fe2+, Zn2+, Pt2+, F-, Cl-, Br-, and I- ions. In general, the D-CTD model demonstrated good accuracy and good transferability in both charge transfer energy and the corresponding charge flow for a wide range of model systems. By distinguishing the intermolecular charge redistribution (charge transfer) under the influence of an external electric field from the accompanying intramolecular charge redistribution (polarization), the D-CTD model is theoretically consistent with current induced dipole-based polarizable dipole models and hence can be easily implemented and parameterized. Along with our previous work in charge penetration-corrected electrostatics, a bottom-up approach constructed water model was also proposed and demonstrated. The structure-maker and structure-breaker roles of cations and anions were also correctly reproduced using Na+, K+, Cl-, and I- ions in the new water model, respectively. This work demonstrates a cost-effective approach to describe the charge transfer phenomena. The water and ion models also show the feasibility of a modulated development approach for future force fields.

Constrained density functional theory calculations for estimation of forward and backward intermolecular charge transfer energy

AbstractCharge transfer (CT) in donor–acceptor complexes can occur in two directions: from donor to acceptor (forward CT, CTF) and from acceptor to donor (backward CT, CTB). For an ethylene and tetrafluoroethylene model system, coupled cluster calculations predict that CTF is more stable than CTB. Meanwhile, density functional theory (DFT) and time‐dependent DFT (TDDFT) employing B3LYP functional show a different CT state order depending on the Hartree–Fock exchange (HFX) contribution. The impact of basis sets as a possible cause to induce such unreasonable CT state reverse along with the increase of HFX was investigated. The physical origin of CT state reversal is examined in terms of molecular orbital energy. We analyzed two additional molecular pairs that feature CT state reversal along with the amount of HFX in B3LYP functional. Despite the reduced gap, we suggest constrained DFT using M06‐HF functional as an effective approach to estimate two CT state energies on equal footing.

Achieving Rapid Ultralow-Temperature Ion Transfer via Constructing Lithium-Anion Nanometric Aggregates to Eliminate Li+-Dipole Interactions.

Sluggish desolvation in extremely cold environments caused by strong Li+-dipole interactions is a key inducement for the capacity decline of a battery. Although the Li+-dipole interaction is reduced by increasing the electrolyte concentration, its high viscosity inevitably limits ion transfer at low temperatures. Herein, Li+-dipole interactions were eliminated to accelerate the migration rate of ions in electrolytes and at the electrode interface via designing Li+-anion nanometric aggregates (LA-nAGGs) in low-concentration electrolytes. Li+ coordinated by TFSI- and FSI- anions instead of a donor solvent promotes the formation of an inorganic-rich interfacial layer and facilitates Li+ transfer. Consequently, the LA-nAGG-type electrolyte demonstrated a high ionic conductivity (0.6 mS cm-1) at -70 °C and a low activation energy of charge transfer (38.24 kJ mol-1), enabling Li||NiFe-Prussian blue derivative cells to deliver ∼83.1% of their room-temperature capacity at -60 °C. This work provides an advanced strategy for the development of low-temperature electrolytes.

Minimized Energy Loss at the Buried Interface of p‐i‐n Perovskite Solar Cells via Accelerating Charge Transfer and Forming p–n Homojunction

AbstractThe energy loss (Eloss) aroused by inefficient charge transfer and large energy level offset at the buried interface of p‐i‐n perovskite solar cells (PVSCs) limits their development. In this work, a BF4− anion‐assisted molecular doping (AMD) strategy is first proposed to improve the charge transfer capability of hole transport layers (HTLs) and reduce the energy level offset at the buried interface of PVSCs. The AMD strategy improves the carrier mobility and density of poly[bis(4‐phenyl) (2,4,6‐trimethylphenyl) amine] (PTAA) and poly[N,N′‐bis(4‐butilphenyl)‐N,N′‐bis(phenyl)‐benzidine] (Poly‐TPD) HTLs while lowering their Fermi levels. Meanwhile, BF4− anions regulate the crystallization and reduce donor‐type iodine vacancies, resulting in the energetics transformation from n‐type to p‐type on the bottom surface of perovskite film. The faster charge transfer and formed p–n homojunction reduce charge recombination and Eloss at the HTL/perovskite buried interface. The PVSCs utilizing AMD treated PTAA and Poly‐TPD as HTLs demonstrate a highest power conversion efficiency (PCE) of 24.26% and 22.65%, along with retaining 90.97% and 85.95% of the initial PCE after maximum power point tracking for 400 h. This work provides an effective way to minimize the Eloss at the buried interface of p‐i‐n PVSCs by accelerating charge transfer and forming p–n homojunctions.