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Recent Submissions

  • Chemoselective Hydrogenation of Alkynes to (Z)-Alkenes Using an Air-Stable Base Metal Catalyst

    Zubar, Viktoriia; Sklyaruk, Jan; Brzozowska, Aleksandra; Rueping, Magnus (Organic Letters, American Chemical Society (ACS), 2020-07-08) [Article]
    A highly selective hydrogenation of alkynes using an air-stable and readily available manganese catalyst has been achieved. The reaction proceeds under mild reaction conditions and tolerates various functional groups, resulting in (Z)-alkenes and allylic alcohols in high yields. Mechanistic experiments suggest that the reaction proceeds via a bifunctional activation involving metal–ligand cooperativity.
  • Numerical Study of CH4 Generation and Transport in XLPE-Insulated Cables in Continuous Vulcanization

    Ruslan, Mohd Fuad Anwari Che; Youn, Dong Joon; Aarons, Roshan; Sun, Yabin; Sun, Shuyu (Materials, MDPI AG, 2020-07-06) [Article]
    <jats:p>In this work, we apply a computational diffusion model based on Fick’s laws to study the generation and transport of methane (CH 4 ) during the production of a cross-linked polyethylene (XLPE) insulated cable. The model takes into account the heating process in a curing tube where most of the cross-linking reaction occurs and the subsequent two-stage cooling process, with water and air as the cooling media. For the calculation of CH 4 generation, the model considers the effect of temperature on the cross-linking reaction selectivity. The cross-linking reaction selectivity is a measure of the preference of cumyloxy to proceed either with a hydrogen abstraction reaction, which produces cumyl alcohol, or with a β -scission reaction, which produces acetophenone and CH 4 . The simulation results show that, during cable production, a significant amount of CH 4 is generated in the XLPE layer, which diffuses out of the cable and into the conductor part of the cable. Therefore, the diffusion pattern becomes a non-uniform radial distribution of CH 4 at the cable take-up point, which corresponds well with existing experimental data. Using the model, we perform a series of parametric studies to determine the effect of the cable production conditions, such as the curing temperature, line speed, and cooling water flow rate, on CH 4 generation and transport during cable production. The results show that the curing temperature has the largest impact on the amount of CH 4 generated and its distribution within the cable. We found that under similar curing and cooling conditions, varying the line speed induces a notable effect on the CH 4 transport within the cable, while the cooling water flow rate had no significant impact.</jats:p>
  • Autoignition of diethyl ether and a diethyl ether/ethanol blend

    Issayev, Gani; Sarathy, Mani; Farooq, Aamir (Fuel, Elsevier BV, 2020-07-04) [Article]
    Binary blends of fast-reacting diethyl ether (DEE) and slow-reacting ethanol (EtOH) are quite promising as renewable replacements for conventional fuels in modern compression ignition engines. In this work, pure diethyl ether and a 50/50 M binary blend of diethyl ether and ethanol (DEE/EtOH) were investigated in a shock tube and a rapid compression machine. Ignition delay times were measured over the temperature range of 550–1000 K, pressures of 20–40 bar, and equivalence ratios of 0.5–1. Literature reaction mechanisms of diethyl ether and ethanol were combined to simulate the reactivity trends of the blends. Species rate-of-production and sensitivity analyses were performed to analyze the interplay between radicals originating from the two fuels. Multistage ignition behavior was observed in both experiments and simulations, with peculiar 3-stage ignition visible at fuel-lean conditions. Kinetic analyses were used to identify the reactions controlling various stages of ignition. Reactivity comparison of DEE/EtOH and dimethyl ether/ethanol (DME/EtOH) blends showed that the oxidation of DEE blends is controlled by acetaldehyde whereas formaldehyde controls the oxidation of DME blends.
  • Unrealistic energy and materials requirement for direct air capture in deep mitigation pathways

    Chatterjee, Sudipta; Huang, Kuo-Wei (Nature Communications, Springer Science and Business Media LLC, 2020-07-03) [Article]
    The increasing global atmospheric CO2 concentration due to heavy reliance on fossil fuels as the primary energy sources (~410 ppm in 2019)1 has made direct extraction or removal of CO2 from ambient air (direct air carbon capture (DACC)) the most logical alternative over traditional modes of carbon capture from large stationary sources because of many of the perceived advantages and compelling arguments2. With the current level of CO2 emissions (32.6 gigatons (Gt)-CO2/year2017)1, Realmonte and co-workers recently imposed the global capacity at 30 Gt-CO2/year as a case study for DACC, and concluded that “in theory DACCS can be an enabling factor for the Paris Agreement objectives” and recommended the policy makers to “support an acceleration in development and deployment of DACCS”3. While challenges of large-scale CO2 utilization and sequestration were recognized and these approaches were deemed impractical4,5, our analysis further showed that the energy and materials requirements for DACC are unrealistic even when the most promising technologies are employed. Thus, DACC is unfortunately only an energetically and financially costly distraction in effective mitigation of climate changes at a meaningful scale before we achieve the status of a significant surplus of carbon-neutral/low-carbon energy.
  • A Highly Conductive Titanium Oxynitride Electron-Selective Contact for Efficient Photovoltaic Devices.

    Yang, Xinbo; Lin, Yuanbao; Liu, Jiang; Liu, Wenzhu; Bi, Qunyu; Song, Xin; Kang, Jingxuan; Xu, Fuzong; Xu, Lujia; Hedhili, Mohamed N.; Baran, Derya; Zhang, Xiaohong; Anthopoulos, Thomas D.; De Wolf, Stefaan (Advanced materials (Deerfield Beach, Fla.), Wiley, 2020-07-03) [Article]
    High-quality carrier-selective contacts with suitable electronic properties are a prerequisite for photovoltaic devices with high power conversion efficiency (PCE). In this work, an efficient electron-selective contact, titanium oxynitride (TiOx Ny ), is developed for crystalline silicon (c-Si) and organic photovoltaic devices. Atomic-layer-deposited TiOx Ny is demonstrated to be highly conductive with a proper work function (4.3 eV) and a wide bandgap (3.4 eV). Thin TiOx Ny films simultaneously provide a moderate surface passivation and enable a low contact resistivity on c-Si surfaces. By implementation of an optimal TiOx Ny -based contact, a state-of-the-art PCE of 22.3% is achieved for a c-Si solar cell featuring a full-area dopant-free electron-selective contact. Simultaneously, conductive TiOx Ny is proven to be an efficient electron-transport layer for organic photovoltaic (OPV) devices. A remarkably high PCE of 17.02% is achieved for an OPV device with an electron-transport TiOx Ny layer, which is superior to conventional ZnO-based devices with a PCE of 16.10%. Atomic-layer-deposited TiOx Ny ETL on a large area with a high uniformity may help accelerate the commercialization of emerging solar technologies.
  • Temperature-resilient solid-state organic artificial synapses for neuromorphic computing

    Melianas, Armantas; Quill, T. J.; LeCroy, G.; Tuchman, Y.; Loo, H. v.; Keene, S. T.; Giovannitti, Alexander; Lee, H. R.; Maria, I. P.; McCulloch, Iain; Salleo, Alberto (Science Advances, American Association for the Advancement of Science (AAAS), 2020-07-03) [Article]
    <jats:p>Devices with tunable resistance are highly sought after for neuromorphic computing. Conventional resistive memories, however, suffer from nonlinear and asymmetric resistance tuning and excessive write noise, degrading artificial neural network (ANN) accelerator performance. Emerging electrochemical random-access memories (ECRAMs) display write linearity, which enables substantially faster ANN training by array programing in parallel. However, state-of-the-art ECRAMs have not yet demonstrated stable and efficient operation at temperatures required for packaged electronic devices (~90°C). Here, we show that (semi)conducting polymers combined with ion gel electrolyte films enable solid-state ECRAMs with stable and nearly temperature-independent operation up to 90°C. These ECRAMs show linear resistance tuning over a >2× dynamic range, 20-nanosecond switching, submicrosecond write-read cycling, low noise, and low-voltage (±1 volt) and low-energy (~80 femtojoules per write) operation combined with excellent endurance (>10$^\{9}$$ write-read operations at 90°C). Demonstration of these high-performance ECRAMs is a fundamental step toward their implementation in hardware ANNs.</jats:p>
  • Simultaneous Bayesian Estimation of Non-Planar Fault Geometry and Spatially-Variable Slip

    Dutta, Rishabh; Jonsson, Sigurjon; Vasyura-Bathke, Hannes (Wiley, 2020-07-02) [Preprint]
    Large earthquakes are usually modeled with simple planar fault surfaces or a combination of several planar fault segments. However, in general, earthquakes occur on faults that are non-planar and exhibit significant geometrical variations in both the along-strike and down-dip directions at all spatial scales. Mapping of surface fault ruptures and high-resolution geodetic observations are increasingly revealing complex fault geometries near the surface and accurate locations of aftershocks often indicate geometrical complexities at depth. With better geodetic data and observations of fault ruptures, more details of complex fault geometries can be estimated resulting in more realistic fault models of large earthquakes. To address this topic, we here parametrize non-planar fault geometries with a set of polynomial parameters that allow for both along-strike and down-dip variations in the fault geometry. Our methodology uses Bayesian inference to estimate the non-planar fault parameters from geodetic data, yielding an ensemble of plausible models that characterize the uncertainties of the non-planar fault geometry and the fault slip. The method is demonstrated using synthetic tests considering checkerboard fault-slip patterns on non-planar fault surfaces with spatially-variable dip and strike angles both in the down-dip and in the along-strike directions. The results show that fault-slip estimations can be biased when a simple planar fault geometry is assumed in presence of significant non-planar geometrical variations. Our method can help to model earthquake fault sources in a more realistic way and may be extended to include multiple non-planar fault segments or other geometrical fault complexities.
  • Rate-dependent viscoelasticity of an impact-hardening polymer under oscillatory shear

    Xu, Yangguang; Lubineau, Gilles; Liao, Guojiang; He, Qianyun; Xing, Tao (Materials Research Express, IOP Publishing, 2020-07-01) [Article]
    The rate-dependent effect of viscoelasticity plays a critical role in the hardening mechanisms of impact-hardening polymers (IHP) when forcefully impacted. In this study, we used dynamic mechanical analysis (DMA) to characterize the rate-dependent viscoelasticity of an IHP under oscillatory shear. We found that the storage modulus increased by three orders of magnitude within the experimental range when the oscillatory frequency varied from 0.1 to 100 rad/s. To further understand the real strain rate effect of IHP, we introduced the Havriliak-Negami (H–N) model to predict the dynamic viscoelastic behaviors of the IHP for a wider frequency range (from zero to infinity) than that applied in the DMA experiments. Based on the H–N model results, we defined a parameter to describe the rate-dependent effect of the IHP, which was not dependent on the frequency range and reflected the intrinsic material properties of IHP. We used the time-temperature superposition principle (TTSP), which extended the experimental range from 0.1 rad s−1 down to 0.005 rad s−1, to verify the accuracy of the rate-dependent viscoelasticity predicted by the H–N model. Finally, we outlined the influence of temperature on the dynamic viscoelastic behaviors of IHP and discussed the phase transition mechanism induced by temperature and the oscillatory frequency. The results presented here not only provide a method (i.e., by combining experimental results with the H–N model results) to characterize the real rate-dependent viscoelasticity of IHP but are also valuable to further our understanding of the impact-hardening mechanisms of IHP.
  • Bulk Spin Torque-Driven Perpendicular Magnetization Switching in L10 FePt Single Layer.

    Tang, Meng; Shen, Ka; Xu, Shijie; Yang, Huanglin; Hu, Shuai; Lü, Weiming; Li, Changjian; Li, Mengsha; Yuan, Zhe; Pennycook, Stephen J; Xia, Ke; Manchon, Aurelien; Zhou, Shiming; Qiu, Xuepeng (Advanced materials (Deerfield Beach, Fla.), Wiley, 2020-06-30) [Article]
    Due to its inherent superior perpendicular magnetocrystalline anisotropy, the FePt in L10 phase enables magnetic storage and memory devices with ultrahigh capacity. However, reversing the FePt magnetic state, and therefore encoding information, has proven to be extremely difficult. Here, it is demonstrated that an electric current can exert a large spin torque on an L10 FePt magnet, ultimately leading to reversible magnetization switching. The spin torque monotonically increases with increasing FePt thickness, exhibiting a bulk characteristic. Meanwhile, the spin torque effective fields and switching efficiency increase as the FePt approaches higher chemical ordering with stronger spin-orbit coupling. The symmetry breaking that generates spin torque within L10 FePt is shown to arise from an inherent structural gradient along the film normal direction. By artificially reversing the structural gradient, an opposite spin torque effect in L10 FePt is demonstrated. At last, the role of the disorder gradient in generating a substantial torque in a single ferromagnet is supported by theoretical calculations. These results will push forward the frontier of material systems for generating spin torques and will have a transformative impact on magnetic storage and spin memory devices with simple architecture, ultrahigh density, and readily application.
  • Evidence for Silica Surface Three- and Five-Membered Metallacycle Intermediates in the Catalytic Cycle of Hydroaminoalkylation of Olefins Using Single-Ti-Metal Catalysts

    Yaacoub, Layal F.; Aljuhani, Maha A.; Jedidi, Abdesslem; Al-Harbi, Manal S.; Almaksoud, Walid; Wackerow, Wiebke; Abou-Hamad, Edy; Pelletier, Jeremie; El Eter, Mohamad; Cavallo, Luigi; Basset, Jean-Marie (Organometallics, American Chemical Society (ACS), 2020-06-30) [Article]
    The single-site silica-supported group IV metal amido complex [Ti(NMe2)4] gives the tris(amido)-supported fragment [(=Si−O−)Ti(−NMe2)3], which transforms into a three-membered metallacycle (called a metallaaziridine) by an αH transfer between two amido ligands. When the three-membered metallacycle reacts with 1-octene, it gives a five-membered metallacycle by insertion of the double bond into the M−C bond of the metallaziridine. These two metallacycles, key intermediates in the catalytic cycle of the hydroaminoalkylation of terminal olefins, were isolated and fully characterized following the surface organometallic chemistry (SOMC) concept and procedures. This paper shows that surface organometallic chemistry can be used to identify and fully characterize three- and five-membered metallacycles of Ti in the hydroaminoalkylation of olefins.
  • QCL-Based Dual-Comb Spectrometer for Multi-Species Measurements at High Temperatures and High Pressures

    Zhang, Guangle; Horvath, Raphael; Liu, Dapeng; Geiser, Markus; Farooq, Aamir (Sensors, MDPI AG, 2020-06-29) [Article]
    <jats:p>Rapid multi-species sensing is an overarching goal in time-resolved studies of chemical kinetics. Most current laser sources cannot achieve this goal due to their narrow spectral coverage and/or slow wavelength scanning. In this work, a novel mid-IR dual-comb spectrometer is utilized for chemical kinetic investigations. The spectrometer is based on two quantum cascade laser frequency combs and provides rapid (4 µs) measurements over a wide spectral range (~1175–1235 cm−1). Here, the spectrometer was applied to make time-resolved absorption measurements of methane, acetone, propene, and propyne at high temperatures (>1000 K) and high pressures (>5 bar) in a shock tube. Such a spectrometer will be of high value in chemical kinetic studies of future fuels.</jats:p>
  • Mechanism of wettability alteration of the calcite {101̄4} surface

    Li, Huifang; Vovusha, Hakkim; Sharma, Sitansh; Singh, Nirpendra; Schwingenschlögl, Udo (Physical Chemistry Chemical Physics, Royal Society of Chemistry (RSC), 2020-06-29) [Article]
    <p>We propose that formation of Na$^{+}$ hydrates plays an important role in the wettability alteration of the calcite {101̄4} surface.</p>
  • All-Polycarbonate Thermoplastic Elastomers Based on Triblock Copolymers Derived from Triethylborane-Mediated Sequential Copolymerization of CO2 with Various Epoxides

    Jia, Mingchen; Zhang, Dongyue; de Kort, Gijs W.; Wilsens, Carolus H. R. M.; Rastogi, Sanjay; Hadjichristidis, Nikos; Gnanou, Yves; Feng, Xiaoshuang (Macromolecules, American Chemical Society (ACS), 2020-06-29) [Article]
    Various oxirane monomers including alkyl ether or allyl-substituted ones such as 1-butene oxide, 1-hexene oxide, 1-octene oxide, butyl glycidyl ether, allyl glycidyl ether, and 2-ethylhexyl glycidyl ether were anionically copolymerized with CO2 into polycarbonates using onium salts as initiator in the presence of triethylborane. All copolymerizations exhibited a “living” character, and the monomer consumption was monitored by in situ Fourier-transform infrared spectroscopy. The various polycarbonate samples obtained were characterized by 1H NMR, GPC, and differential scanning calorimetry. In a second step, all-polycarbonate triblock copolymers demonstrating elastomeric behavior were obtained in one pot by sequential copolymerization of CO2 with two different epoxides, using a difunctional initiator. 1-Octene oxide was first copolymerized with CO2 to form the central soft poly(octene carbonate) block which was flanked by two external rigid poly(cyclohexene carbonate) blocks obtained through subsequent copolymerization of cyclohexene oxide with CO2. Upon varying the ratio of 1-octene oxide to cyclohexene oxide and their respective ratios to the initiator, three all-polycarbonate triblock samples were prepared with molar masses of about 350 kg/mol and 22, 26, and 29 mol % hard block content, respectively. The resulting triblock copolymers were analyzed using 1H NMR, GPC, thermogravimetric analysis, differential scanning calorimetry, and atomic force microscopy. All three samples demonstrated typical elastomeric behavior characterized by a high elongation at break and ultimate tensile strength in the same range as those of other natural and synthetic rubbers, in particular those used in applications such as tissue engineering.
  • Racemic alcohols to optically pure amine precursors enabled by catalyst dynamic kinetic resolution: experiment and computation

    Azofra, Luis Miguel; Tran, Mai Anh; Zubar, Viktoriia; Cavallo, Luigi; Rueping, Magnus; El-Sepelgy, Osama (Chemical Communications, Royal Society of Chemistry (RSC), 2020-06-29) [Article]
    <p>An unprecedented base metal catalysed asymmetric synthesis of α-chiral amine precursors from racemic alcohols is reported. This redox-neutral reaction utilises a bench-stable manganese complex and Ellman’s sulfinamide as versatile ammonia...</p>
  • Induced spin textures at 3d transition metal–topological insulator interfaces

    Laref, Slimane; Ghosh, Sumit; Tsymbal, Evgeny Y.; Manchon, Aurelien (Physical Review B, American Physical Society (APS), 2020-06-26) [Article]
    While some of the most elegant applications of topological insulators, such as the quantum anomalous Hall effect, require the preservation of Dirac surface states in the presence of time-reversal symmetry breaking, other phenomena such as spin-charge conversion rather rely on the ability for these surface states to imprint their spin texture on adjacent magnetic layers. In this Rapid Communication, we investigate the spin-momentum locking of the surface states of a wide range of monolayer transition metals (3d-TM) deposited on top of Bi2Se3 topological insulators using first-principles calculations. We find an anticorrelation between the magnetic moment of the 3d-TM and the magnitude of the spin-momentum locking induced by the Dirac surface states. While the magnetic moment is large in the first half of the 3d series, following Hund’s rule, the spin-momentum locking is maximum in the second half of the series. We explain this trend as arising from a compromise between intra-atomic magnetic exchange and covalent bonding between the 3d-TM overlayer and the Dirac surface states. As a result, while Cr and Mn overlayers can be used successfully for the observation of the quantum anomalous Hall effect or the realization of axion insulators, Co and Ni are substantially more efficient for spin-charge conversion effects, e.g., spin-orbit torque and charge pumping.
  • Significant Impact of Exposed Facets on the BiVO4 Material Performance for Photocatalytic Water Splitting Reactions

    Lardhi, Sheikha F.; Cavallo, Luigi; Harb, Moussab (The Journal of Physical Chemistry Letters, American Chemical Society (ACS), 2020-06-26) [Article]
    The impact of the four predominant (010), (110), (001), and (121) exposed facets obtained experimentally for monoclinic BiVO4 on its photocatalytic performance for water splitting reactions is investigated on the basis of the hybrid density functional theory including the spin–orbit coupling. Although their electronic structure is similar, their transport and redox properties reveal anisotropic characters based on the crystal orientation and termination. The particular role of each facet in proton reduction was correlated with the surface Bi coordination number and their geometrical distribution. Our work predicts the (001) facet as the only good candidate for both HER and OER, while the (010) facet is a fitting candidate for OER only. The (110) and (121) surfaces are acceptable candidates only for OER but less potential than (001) and (010). These outcomes will efficiently conduct experimentalists for an attentive design of facet-oriented BiVO4 samples toward improving water oxidation and proton reduction.
  • Using sodium acetate for the synthesis of [Au(NHC)X] complexes

    Scattolin, Thomas; Tzouras, Nikolaos V.; Falivene, Laura; Cavallo, Luigi; Nolan, Steven P. (Dalton Transactions, Royal Society of Chemistry (RSC), 2020-06-26) [Article]
    <p>Sodium acetate enables the synthesis of [Au(NHC)Cl] complexes, as well as their Au-alkynyl and -thiolato derivatives in high yields, under air and in technical grade, green solvents. The mild synthetic methods are also investigated computationally.</p>
  • Flexible C6BN Monolayers As Promising Anode Materials for High-Performance K-Ion Batteries

    Xiang, Pan; Sharma, Sitansh; Wang, Zhiming M.; Wu, Jiang; Schwingenschlögl, Udo (ACS Applied Materials & Interfaces, American Chemical Society (ACS), 2020-06-25) [Article]
    K-ion batteries attract extensive attention and research efforts because of the high energy density, low cost, and high abundance of K. Although they are considered suitable alternatives to Li-ion batteries, the absence of high-performance electrode materials is a major obstacle to implementation. On the basis of density functional theory, we systematically study the feasibility of a recently synthesized C6BN monolayer as anode material for K-ion batteries. The specific capacity is calculated to be 553 mAh/g (K2C6BN), i.e., about twice that of graphite. The C6BN monolayer is characterized by high strength (in-plane stiffness of 309 N/m), excellent flexibility (bending strength of 1.30 eV), low output voltage (average open circuit voltage of 0.16 V), and excellent rate performance (diffusion barrier of 0.09 eV). We also propose two new C6BN monolayers. One has a slightly higher total energy (0.10 eV) than the synthesized C6BN monolayer, exhibiting enhanced electronic properties and affinity to K. The other is even energetically favorable due to B-N bonding. All three C6BN monolayers show good dynamical, thermal, and mechanical stabilities. We demonstrate excellent cyclability and improved conductivity by K adsorption, suggesting great potential in flexible energy-storage devices.
  • Volcano-wide deformation after the 2017 Erta Ale dike intrusion, Ethiopia, observed with radar interferometry

    Xu, Wenbin; Xie, Lei; Aoki, Yosuke; Rivalta, Eleonora; Jonsson, Sigurjon (Journal of Geophysical Research: Solid Earth, American Geophysical Union (AGU), 2020-06-25) [Article]
    Erta Ale volcano erupted on 16 Jan. 2017 in a difficult-to-access terrain in the Erta Ale volcanic range in Ethiopia. Like many other rifting ridge volcanoes, little is known about the properties of the deep magma plumbing system. Here, we analyze interferometric synthetic aperture radar data from different satellites between late Jan. 2017 and May 2019 to study the ground deformation after the start of the intrusion to infer the possible geometry and volume change of the magma reservoir that fed the eruption. We identified volcano-wide subsidence of up to 9 cm and horizontal contraction of up to ~5 cm that extend from Erta Ale to neighboring volcanoes. The modeling results suggest that an off-rift NE-SW elongated mid-crustal source is required to explain the observed volcano-wide deformation, but the depth is poorly constrained and the shape is complex. We suggest the presence of vertical interactions between stacked mid-crustal magma sources. Our study demonstrates that a considerable volume of melt could have been stored in mid-crustal magma reservoirs within the slow-spreading Erta Ale ridge to facilitate recent volcanic activity.
  • Structurally Tunable Two-Dimensional Layered Perovskites: From Confinement and Enhanced Charge Transport to Prolonged Hot Carrier Cooling Dynamics.

    El-Ballouli, Ala’a O.; Bakr, Osman; Mohammed, Omar F. (The journal of physical chemistry letters, American Chemical Society (ACS), 2020-06-24) [Article]
    Two-dimensional (2D) layered metal halide perovskites are potential alternatives to three-dimensional perovskites in optoelectronic applications owing to their improved photostabilities and chemical stabilities. Recent investigations of 2D metal halide perovskites have demonstrated interesting optical and electronic properties of various structures that are controlled by their elemental composition and organic spacers. However, photovoltaic devices that utilize 2D perovskites suffer from poor device efficiency due to inefficient charge carrier separation and extraction. In this Perspective, we shed light on confinement control and structural variation strategies that provide better parameters for the efficient collection of charges. The influence of these strategies on the exciton binding energies, charge-carrier mobilities, hot-carrier dynamics, and electron-phonon coupling in 2D perovskites is thoroughly discussed; these parameters highlight unique opportunities for further system optimization. Beyond the tunability of these fundamental parameters, we conclude this Perspective with the most notable strategies for attaining 2D perovskites with reduced bandgaps to better suit photovoltaic applications.

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