Search

Highlights: Atomically dispersed metal atoms effectively enhance energy level alignment and reduce energy losses at the electrode interfaces. The optimized carbon-based perovskite solar cells achieve a power conversion efficiency (PCE) of 22.61% and maintain 94.4% of their initial PCE after 1000 h under continuous illumination without encapsulation. Carbon-based perovskite solar cells (C-PSCs) exhibit notable stability and durability. However, the power conversion efficiency (PCE) is significantly hindered by energy level mismatches, which result in interfacial charge transport barriers at the electrode-related interfaces. Herein, we report a back electrode that utilizes atomically dispersed metallic cobalt (Co) in carbon nanosheets (Co1/CN) to adjust the interfacial energy levels. The electrons in the d-orbitals of Co atoms disrupt the electronic symmetry of the carbon nanosheets (CN), inducing a redistribution of the electronic density of states that leads to a downward shift in the Fermi level and a significantly reduced interfacial energy barrier. As a result, the C-PSCs using Co1/CN as back electrodes achieve a notable PCE of 22.61% with exceptional long-term stability, maintaining 94.4% of their initial efficiency after 1000 h of continuous illumination without encapsulation. This work provides a promising universal method to regulate the energy level of carbon electrodes for C-PSCs and paves the way for more efficient, stable, and scalable solar technologies toward commercialization. [ABSTRACT FROM AUTHOR]

All that remains to reliably beat the 20% efficiency hurdle in organic solar cells are the relatively low open‐circuit voltages (VOC). A still‐needed step toward solving this problem is to shed light on the mechanisms behind these losses, and herein it is focused on understanding the roll‐off of VOC at low temperatures, which has been linked to various detrimental processes. Here, a light intensity sweep is added to the temperature‐dependent measurements and the resulting trends are compared with a kinetic analytical model that not only incorporates all previously suggested explanations for the temperature dependence of VOC, but, importantly, also includes carrier density contributions to the electron and hole mobilities by treating the density of states (DOS) of the active layer as a two‐level system. It is found that this description is sufficient to quantitatively explain VOC roll‐off in terms of charges getting trapped in intrinsic tail states of the Gaussian DOS without having to assume the presence of extrinsic traps. [ABSTRACT FROM AUTHOR]

This paper deals with the analysis of an instationary drift-diffusion model for perovskite solar cells including Fermi–Dirac statistics for electrons and holes and Blakemore statistics for the mobile ionic vacancies in the perovskite layer. The free energy functional is related to this choice of the statistical relations.Exemplary simulations varying the mobility of the ionic vacancy demonstrate the necessity to include the migration of ionic vacancies in the model frame. To prove the existence of weak solutions, first a problem with regularized state equations and reaction terms on any arbitrarily chosen finite time interval is considered. Its solvability follows from a time discretization argument and passage to the time-continuous limit. Applying Moser iteration techniques, a priori estimates for densities, chemical potentials and the electrostatic potential of its solutions are derived that are independent of the regularization level, which in turn ensure the existence of solutions to the original problem. [ABSTRACT FROM AUTHOR]

Abstract Perovskite solar cells (PSCs) are an ideal candidate for next‐generation photovoltaic applications but face many challenges for their wider application, including uncontrolled fast crystallization, trap‐assisted nonradiative recombination, and inefficient charge transport. Herein, a multistage regulation (MSR) strategy for addressing these challenges is proposed via the introduction of fluorine‐rich small molecules with multiple active points (i.e., 1‐[Bis(trifluoromethanesulfonyl)methyl]‐ 2,3,4,5,6‐pentafluorobenzene (TFSP)) into the precursor solution of the perovskite film. The addition of TFSP effectively delays and regulates the crystallization and growth process of the perovskite film for larger grains and fewer defects, and it effectively improves the coverage of self‐assembled molecules for efficient charge transport. The multiple active points of TFSP induce a strong binding affinity with uncoordinated defects in the perovskite film. Moreover, the high fluorine content of TFSP induces strong electronegativity to establish a high binding strength between the perovskite film and electron transport layer. Finally, PSCs prepared by the MSR strategy demonstrated an optimal power conversion efficiency (PCE) of 25.46% and maintained 91.16% of the initial PCE under nonpackaged air conditions and at a relative humidity of 45% after 3000 h.

We theoretically study the 2D Su-Schrieffer-Heeger model in the context of Floquet topological insulators (FTIs). FTIs are systems which undergo topological phase transitions, governed by Chern numbers, as a result of time reversal symmetry (TRS) breaking by a time periodic process. In our proposed model, the condition of TRS breaking is achieved by circularly polarized light irradiation. We analytically show that TRS breaking is forbidden in the absence of second order neighbors hopping. In the absence of light irradiation, we identify a symmetry-protected degeneracy and prove the appearance of a flat band along a specific direction in the momentum space. Furthermore, we employ a novel method to show that the four unit cell atoms, in the absence of irradiation, can be interpreted as conserved spin states. With the breaking of TRS via light irradiation, these spin states are no longer conserved, leading to the emergence of chiral edge states. We also show how the interplay between the TRS breaking and dimerization leads to some complex topological phase transitions. The validity of our findings is substantiated through Chern numbers, spectral properties, localization of chiral edge states and simulations of quantum Hall transport. Our model is suitable not only for condensed matter (materials), but also for cold gases trapped in optical lattices or topolectrical circuits.

[Display omitted] • Exceptional La 2 O 3 (003) facet designed by molten salt impregnation method. • La 2 O 3 oriented grown into a lamellar structure by molten salt impregnation method. • Unique charge transport, promoted H 2 O adsorption & dissociation of CuLa catalysts. • Durability evaluation conducted with discoidal mesh-type catalysts. • Combining DFT calculations with in-situ FTIR. The dispersion of active components and the strong metal-support interactions (SMSI) are closely associated with the lifespans and activities of catalysts in methanol steam reforming (MSR). In this study, a copper-based (Cu-based) catalyst featuring a unique lamellar structure and (003) facet for lanthanum oxide (La 2 O 3) was prepared by the molten salt impregnation method for the first time. Compared to the unmodified Cu/γ-Al 2 O 3 /Al catalyst, the lifetime was enhanced eightfold, reaching 150 h. La 2 O 3 can lead to the formation of a fence structure, which enhances the dispersion of Cu through a domain-limiting effect. Additionally, the Cu atoms near the Cu(111)/La 2 O 3 (003) interface exhibit a higher degree of electron loss compared to La 2 O 3 with polycrystalline facets. This characteristic contributes to the enhanced water adsorption and dissociation capacity of CuLa catalysts. These two factors lead to superior catalytic activity and lifespan of CuLa-2 h. This study offers insights into catalyst microstructure and green chemistry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mn-Fe 2 O 3 /rGO is constructed by heteroatom doped and interface engineering strategy. • DFTs show Mn2+ doped would induce spin polarization in Fe 3d orbital electrons. • Mn-Fe 2 O 3 /rGO delivers a negative MR effect at room temperature. • Superior supercapacitor performance is achieved (220.19 W h kg−1 at 3.93 kW kg−1). Magnetic supercapacitors have garnered significant attention, with notable progress in recent years. However, the underlying mechanisms remain unclear and require further investigation for future energy storage applications. In this study, we designed and fabricated Mn-Fe 2 O 3 /reduced graphene oxide (Mn-Fe 2 O 3 /rGO) nanostructures by employing heteroatom doping and interface engineering. Theoretical calculations showed that incorporating Mn2+ into Fe 2 O 3 modulates electron localization around Fe atoms, leading to spin polarization in Fe 3d orbital electrons. Our experiments demonstrated that the optimized Mn-Fe 2 O 3 /rGO nanostructure processes ferromagnetic properties with a negative magnetoresistance effect at room temperature, suggesting that substantial spin-polarized charges rapidly participate in surface charge–discharge reactions under an applied magnetic field. This phenomenon resulted in a remarkable specific capacitance of 2956.4 F g−1 at 1 A g−1, along with superior cyclic stability. Additionally, the asymmetric supercapacitor device achieved an energy density of 220.19 W h kg−1 at a power density of 3.93 kW kg−1, with excellent capacitance retention of 98.5 % after 5000 cycles. This work paves the way for improving the performance of magnetic supercapacitors based on metal oxide electrode materials. [ABSTRACT FROM AUTHOR]

The integration of 2D and 3D perovskite materials can enhance the stability and efficiency of perovskite solar cells. This study examines the impact of modifying common organic spacers—2AI, PEA, and FPEA—with formamidinium (FA), guanidinium (GA), and methylenediammonium (MDA) cations on the interface between 2D and 3D layers in FAPbI 3 perovskite materials. Structural analysis, electrostatic mapping, and energy calculations reveal that GA modification strengthens binding but destabilizes stacking, while MDA modification improves stability and charge transfer. These findings offer valuable insights into optimizing organic spacer modifications for 2D/3D perovskite solar cell performance. [Display omitted] • Modified organic spacers affect 2D/3D perovskite interface stability. • GA-modified spacers enhance binding but destabilize molecular stacking. • MDA-modified spacers improve both binding and stacking stability. • Charge density maps reveal distinct electron transfer patterns. • Spacer modifications offer pathways to optimize perovskite solar cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • Improvement in fluid properties of electronic ink. • Excellent response in vacuum pressure variation. • Useful active sensor material for detection of vacuum break. • Electrical drift reduction by introducing elastomeric O–H bond. • Economic and green material system. Polyaniline (PANI) powder in its emeraldine salt form was blended with various concentrations of polyvinyl alcohol (PVA) to create semiconducting inks with desired fluid properties. These inks were coated on cellulose paper, and their resistive responses were tested under different vacuum pressures. Enhanced conductivity and reduced creep behavior were achieved by incorporating an O–H bond between the H of PANI and O of PVA, which stabilizes the polymer structure. This bonding minimizes electrical drift, improving the reliability of the synthesized inks for applications such as designing flexible circuits and fabricating thermoelectric generators. The strain field developed under vacuum is accountable for the observed variation in electrical properties. Due to the increase in strain field, the polaron hopping barrier increases, and as a result, the effective conductivity decreases with a decrease in pressure. These 'use-and-throw' sensors are economical, adaptable, and environmentally friendly, ideal for various disposable electronics and sensing applications. [ABSTRACT FROM AUTHOR]

Magic-sized nanoclusters (MSCs) have been attracting enduring interest by virtue of the quantum confinement effect, discrete energy band structure, and enriched catalytic active sites. Nevertheless, up to date, exploration of MSCs artificial photosystems and fine-tuning of spatial vectorial charge transfer in photoredox catalysis have so far been scarcely reported. Hence, we employed a facile and easily accessible layer-by-layer (LbL) assembly strategy to highly ordered, alternately, and periodically deposit oppositely charged tailor-made transition metal chalcogenides (TMCs) MSCs and non-conjugated polymer (NCP) building blocks on the MO substrate, resulting in the MO/(NCP-TMCs MSCs) n multilayer heterostructures. It is affirmed that the ultra-thin NCP uniformly intercalated at the interface of every TMCs MSCs layer fosters the unidirectional electron flow from TMCs MSCs to MO substrate with the assistance of NCP, and moreover the multilayered interface configuration benefits the establishment of cascade tandem charge transfer route, synergistically giving rise to the significantly enhanced charge separation and boosted solar water oxidation performances of MO/(TMCs MSCs-NCP) n heterostructure under simulated solar light irradiation. Our work elucidates the specific roles of NCP and MSCs as charge relay mediators and photosensitizers, affording a quintessential paradigm to rationally regulate the photocarrier transport and separation over MSCs for solar energy conversion., (© 2025 Wiley‐VCH GmbH.)

The fill factor (FF) is a critical parameter for solar cell efficiency, but its analytical description is challenging due to the interplay between recombination and charge extraction processes. A significant factor contributing toFFlosses, beyond recombination, that has not received much attention is the influence of charge transport. In most state-of-the-art organic solar cells, the primary limitations of theFFdo not just arise from non-radiative recombination, but also from low conductivity of the organic semiconductors. A closer look reveals that even in the highest efficiency cells, performance losses due to transport resistance are significant. This finding highlights the need for refined models to predict theFFaccurately. Here, we extend the analytical model for transport resistance to a more general case by incorporating energetic disorder. We introduce a straightforward set of equations to predict theFFof a solar cell, enabling the differentiation of losses attributed to recombination and transport resistance. Our analytical model is validated with a large set of experimental current-voltage and light intensity-dependent open-circuit voltage data for a wide range of temperatures. Based on our findings, we provide valuable insights into strategies for mitigatingFFlosses, guiding the development of more efficient solar cell designs and optimisation strategies., (Creative Commons Attribution license.)

One key aspect for the development of functional molecular electronic devices is the ability to precisely tune and reversibly switch the conductance of individual molecules in electrode-molecule-electrode junctions in response to external stimuli. In this work, we present a new approach to access molecular switches by deliberately controlling the flexibility in the molecular backbone. We here describe two new conductance switches based on bis(triarylamines) that rely on the reversible toggling between two conformers, each associated with vastly different conductances. By molecular design, we were able to realize an on/off ratio G high /G low of ~10 3 , which is one of the largest values reported to date. Flicker noise analysis and molecular transport calculations indicate that on/off switching relies on a change of the conduction pathway and vast differences in molecule-electrode coupling. We thereby provide a new scaffold for further development of molecular conductance switches that are both efficient and easily refined., (© 2024 The Author(s). Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

A promising candidate for X-ray detection is layered hybrid double perovskites (LHDPs) with excellent structural stability, but their sensitivity is generally limited by unsatisfactory interlayer charge transport. Herein, employing one ethylenediamine (EDA) chain as a structural inducer, we successfully obtain unusual Dion-Jacobson (DJ) phase LHDPs, (EDABr) 4 AgBiBr 8 and (EDABr) 4 CuBiBr 8 , featuring a Ruddlesden-Popper-like (RP-like) interlayer. Thanks to the bridging of bromine anions, organic cations are linked via charge-assisted hydrogen bonds, where two ionic spacers are orderly woven into a supramolecular framework. Consequently, the RP-like interlayer space is regulated by the dual-ion-woven supramolecular framework with embedded charge-assisted hydrogen bond networks, remarkably enriching interlayer interactions and boosting charge transport. Through theoretical calculations, structural roles of the supramolecular framework are elucidated by extra orbital contribution and large diffusion barrier of Br anions. As proof of concept, the sensitivity of RP-like devices up to 5250 μC Gy air -1  cm -2 is a record-high of LHDP-based X-ray detectors for now, while a low detection limit (91 nGy air  s -1 ) and outstanding radiation-resistant capability (50 Gy air ) are achieved. Moreover, an oriented membrane device is prepared to demonstrate high-performance X-ray tomography. These findings offer a brand-new interlayer-modulation strategy for the construction of sensitive and stable scintillation semiconductors., (© 2024 Wiley-VCH GmbH.)

Predictive approaches and rules to connect and combine molecular circuit components are required to realize the potential of molecular electronics and develop miniaturized integrated circuits. To this end, we have recently demonstrated a bis(terpyridine)-based molecular breadboard with four conductance states formed by the superposition of five 2-5 ring circuits. Here, we develop a generic analytical/statistical model to describe break-junction data and use it to extract the conductance of the five embedded circuits in the bis-terpyridine-based molecular breadboard junction. The model can be used to experimentally verify and tune the electronic properties of constituent molecular circuits within breadboard junctions, a key step toward developing functional circuitry. Further, our study provides a general framework to simulate and analyze break-junction conductance histograms of complex molecular junctions with more than two electrode anchoring groups.

Heterogeneous integration of emerging two-dimensional (2D) materials with mature three-dimensional (3D) silicon-based semiconductor technology presents a promising approach for the future development of energy-efficient, function-rich nanoelectronic devices. In this study, we designed a mixed-dimensional junction structure in which a 2D monolayer (e.g., graphene, MoS 2 , and h-BN) is sandwiched between a metal (e.g., Ti, Au, and Pd) and a 3D semiconductor (e.g., p-Si) to investigate charge transport properties exclusively in an out-of-plane (OoP) direction. The role of 2D monolayers as either an OoP metal-to-semiconductor charge injection barrier or an OoP semiconductor-to-metal charge collection barrier was comparatively evaluated. Compared to monolayer graphene, monolayer MoS 2 and h-BN effectively modulate OoP metal-to-semiconductor charge injection through a barrier tunneling effect. Their effective OoP resistance and resistivity were extracted using a resistors-in-series model. Intriguingly, when functioning as a semiconductor-to-metal charge collection barrier, all 2D monolayers become electronically "transparent" (close to zero resistance) when a high OoP voltage (greater than the built-in voltage) is applied. As a mixed-dimensional integrated diode, the Ti/MoS 2 /p-Si and Au/MoS 2 /p-Si configurations exhibit both high OoP rectification ratios (5.4 × 10 4 ) and conductance (1.3 × 10 5 S/m 2 ). Our work demonstrates the tunable OoP charge transport characteristics at a 2D/3D interface, suggesting the opportunity for 2D/3D heterogeneous integration, even with sub-1 nm thick 2D monolayers, to enhance modern Si-based electronic devices.

Two-dimensional lead-halide perovskites provide a more robust alternative to three-dimensional perovskites in solar energy and optoelectronic applications due to increased chemical stability afforded by interlayer ligands. At the same time, the ligands create barriers for interlayer charge transport, reducing device performance. Using a recently developed ab initio simulation methodology, we demonstrate that ligand fluorination can enhance both hole and electron mobility by 1-2 orders of magnitude. The simulations show that the enhancement arises primarily from improved structural order and reduced thermal atomic fluctuations in the system rather than increased interlayer electronic coupling. Arising from stronger hydrogen bonding and dipolar interactions, the higher structural stability decreases the reorganization energy that enters the Marcus formula and increases the charge transfer rate. The detailed atomistic insights into the electron and hole transfer in layered perovskites indicate that the use of interlayer ligands that make the overall structure more robust is beneficial simultaneously for chemical stability and charge transport, providing an important guideline for the design of new, efficient materials.

Heavy atom effects can be used to enhance intermolecular interaction, regulate quinoidal resonance properties, increase bandwidths, and tune diradical characters, which have significant impacts on organic optoelectronic devices, such as organic field-effect transistors (OFETs), organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), etc. Meanwhile, the introduction of heavy atoms is shown to promote charge transfer, enhance air stability, and improve device performances in the field of organic thermoelectrics (OTEs). Thus, heavy atom effects are receiving more and more attention. However, regulating heavy atoms in organic semiconductors is still meeting great challenges. For example, heavy atoms will lead to solubility and stability issues (tellurium substitution) and lack of versatile design strategy and effective synthetic methods to be incorporated into organic semiconductors, which limit their application in electronic devices. Therefore, this work timely summarizes the unique functionalities of heavy atom effects, and up-to-date progress in organic electronics including OFETs, OPVs, OLEDs, and OTEs, while the structure-performance relationships between molecular designs and electronic devices are clearly elucidated. Furthermore, this review systematically analyzes the remaining challenges in regulating heavy atoms within organic semiconductors, and design strategies toward efficient and stable organic semiconductors by the introduction of novel heavy atoms regulation are proposed., (© 2024 Wiley‐VCH GmbH.)

Poly (heptazine imide) (PHI), a classic 2D polymeric photocatalyst, represents a promising organic semiconductor for photocatalytic overall water splitting (POWS). However, since the key bottleneck in POWS of PHI remains unclear, its quantum efficiency of POWS is extremely restrained. To identify the key obstacle in POWS on the PHI, a series of PHI with different stacking modes is synthesized by tuning interlayer cations. The structural characterizations revealed that tuning the interlayer cations of PHI can induce rearrangements in interlayer stacking modes. Additionally, charge carriers dynamics uncover that optimizing the interlayer stacking modes of PHI can promote exciton diffusion and prolong the photoexcited electron lifetimes, thus improving the concentration of surface-reaching charge. More importantly, this confirms that the POWS activity of PHI is closely correlated with the interlayer stacking modes. This work offers new insight into structural regulation for governing charge-transport dynamics and the activity of 2D polymeric photocatalysts., (© 2024 Wiley‐VCH GmbH.)

Constructing charge-selective heterointerface with minimized defect state and matched energy level alignment is essential to reduce nonradiative recombination for achieving high-performance perovskite solar cells (PSCs). Herein, a bimolecular passivation-dipole bridge comprised of sodium phenylmethanesulfonate (SPM) and 2-phenylethylammonium iodide (PEAI) is carefully developed to regulate perovskite heterointerface. SPM passivates defect states and upshifts Fermi level (E F ) of perovskite surface, and subsequent PEAI further induces additional negative dipole and causes the surface E F of perovskite pinning to negative polaron transport state of electron transport layer PCBM, which significantly promotes electron extraction at the perovskite electron-selective contact. These advantages are confirmed by a remarkably improved efficiency from 21.74% for control to 25.12% for treated PSC with excellent stability. Moreover, corresponding nonradiative recombination loss impressively diminishes from 123 to 70 meV, and charge transport-induced fill factor loss is only 3.00%. This work provides a promising approach via passivation-energetic synergy for engineering perovskite heterointerface toward highly efficient and stable PSCs., (© 2024 Wiley‐VCH GmbH.)