scispace - formally typeset
Search or ask a question

Showing papers in "ACS energy letters in 2017"


Journal ArticleDOI
TL;DR: In this paper, the potential and limitations of nickel-rich cathode materials are compared with reference to realistic target values from the automotive industry, and how future automotive targets can be achieved through fine control of the structural and microstructural properties.
Abstract: Future generations of electric vehicles require driving ranges of at least 300 miles to successfully penetrate the mass consumer market. A significant improvement in the energy density of lithium batteries is mandatory while also maintaining similar or improved rate capability, lifetime, cost, and safety. The vast majority of electric vehicles that will appear on the market in the next 10 years will employ nickel-rich cathode materials, LiNi1–x–yCoxAlyO2 and LiNi1–x–yCoxMnyO2 (x + y < 0.2), in particular. Here, the potential and limitations of these cathode materials are critically compared with reference to realistic target values from the automotive industry. Moreover, we show how future automotive targets can be achieved through fine control of the structural and microstructural properties.

938 citations


Journal ArticleDOI
TL;DR: In this paper, the authors outline the mechanisms that set a fundamental upper limit to charge-carrier mobility values in metal halide perovskites and reveal how they may be tuned through changes in stoichiometry.
Abstract: Perovskite photovoltaic cells have seen a remarkable rise in power conversion efficiencies over a period of only a few years. Much of this performance is underpinned by the favorable charge-carrier mobilities in metal halide perovskites (MHPs), which are remarkably high for materials with such facile and versatile processing routes. This Perspective outlines the mechanisms that set a fundamental upper limit to charge-carrier mobility values in MHPs and reveals how they may be tuned through changes in stoichiometry. In addition, extrinsic effects such as grain size, energetic disorder, and self-doping are discussed for specific MHPs in the context of remedies designed to avoid them.

843 citations



Journal ArticleDOI
TL;DR: The origins of the significantly blue-shifted emission from CsPbBr3 nanocrystals and the synthetic strategies toward fabrication of stable perovskite nanocrystal materials with emission in the red and infrared parts of the optical spectrum are discussed, related to fabrication of mixed cation compounds guided by Goldschmidt tolerance factor considerations.
Abstract: This Perspective outlines basic structural and optical properties of lead halide perovskite colloidal nanocrystals, highlighting differences and similarities between them and conventional II–VI and III–V semiconductor quantum dots. A detailed insight into two important issues inherent to lead halide perovskite nanocrystals then follows, namely, the advantages of defect tolerance and the necessity to improve their stability in environmental conditions. The defect tolerance of lead halide perovskites offers an impetus to search for similar attributes in other related heavy metal-free compounds. We discuss the origins of the significantly blue-shifted emission from CsPbBr3 nanocrystals and the synthetic strategies toward fabrication of stable perovskite nanocrystal materials with emission in the red and infrared parts of the optical spectrum, which are related to fabrication of mixed cation compounds guided by Goldschmidt tolerance factor considerations. We conclude with the view on perspectives of use of th...

813 citations


Journal ArticleDOI
TL;DR: A direct correlation is found between the density of traps, thedensity of mobile ionic defects, and the degree of hysteresis observed in the current–voltage (J–V) characteristics of perovskite solar cells.
Abstract: Trap-assisted recombination, despite being lower as compared with traditional inorganic solar cells, is still the dominant recombination mechanism in perovskite solar cells (PSCs) and limits their efficiency. We investigate the attributes of the primary trap-assisted recombination channels (grain boundaries and interfaces) and their correlation to defect ions in PSCs. We achieve this by using a validated device model to fit the simulations to the experimental data of efficient vacuum-deposited p–i–n and n–i–p CH3NH3PbI3 solar cells, including the light intensity dependence of the open-circuit voltage and fill factor. We find that, despite the presence of traps at interfaces and grain boundaries (GBs), their neutral (when filled with photogenerated charges) disposition along with the long-lived nature of holes leads to the high performance of PSCs. The sign of the traps (when filled) is of little importance in efficient solar cells with compact morphologies (fused GBs, low trap density). On the other hand,...

739 citations


Journal ArticleDOI
TL;DR: In this paper, the current status and latest advances in metal-air battery research for both aqueous (e.g., Zn-air) and nonaqueous systems are surveyed.
Abstract: Metal–air batteries have a theoretical energy density that is much higher than that of lithium-ion batteries and are frequently advocated as a solution toward next-generation electrochemical energy storage for applications including electric vehicles or grid energy storage. However, they have not fulfilled their full potential because of challenges associated with the metal anode, air cathode, and electrolyte. These challenges will have to be properly resolved before metal–air batteries can become a practical reality and be deployed on a large scale. Here we survey the current status and latest advances in metal–air battery research for both aqueous (e.g., Zn–air) and nonaqueous (e.g., Li–air) systems. An overview of the general technical issues confronting their development is presented, and our perspective on possible solutions is offered.

642 citations


Journal ArticleDOI
TL;DR: In this paper, the authors highlight an often less noted route to improving energy density: increasing the Li+ transference number of the electrolyte, and demonstrate that electrolytes with modestly higher transference numbers compared to traditional carbonate-based liquid electrolytes would allow higher power densities and enable faster charging, even if their conductivity was substantially lower than that of conventional electrolytes.
Abstract: The continued search for routes to improve the power and energy density of lithium ion batteries for electric vehicles and consumer electronics has resulted in significant innovation in all cell components, particularly in electrode materials design. In this Review, we highlight an often less noted route to improving energy density: increasing the Li+ transference number of the electrolyte. Turning to Newman’s original lithium ion battery models, we demonstrate that electrolytes with modestly higher Li+ transference numbers compared to traditional carbonate-based liquid electrolytes would allow higher power densities and enable faster charging (e.g., >2C), even if their conductivity was substantially lower than that of conventional electrolytes. Most current research in high transference number electrolytes (HTNEs) focuses on ceramic electrolytes, polymer electrolytes, and ionomer membranes filled with nonaqueous solvents. We highlight a number of the challenges limiting current HTNE systems and suggest a...

516 citations


Journal ArticleDOI
TL;DR: In this paper, the authors highlight the advantages of this approach with discussions focused on potential applications in the transportation sector together with analysis of technical requirements, limitations, and costs for selective hydrogen generation from formic acid.
Abstract: The high volumetric capacity (53 g H2/L) and its low toxicity and flammability under ambient conditions make formic acid a promising hydrogen energy carrier. Particularly, in the past decade, significant advancements have been achieved in catalyst development for selective hydrogen generation from formic acid. This Perspective highlights the advantages of this approach with discussions focused on potential applications in the transportation sector together with analysis of technical requirements, limitations, and costs.

508 citations


Journal ArticleDOI
TL;DR: Li et al. as discussed by the authors reported the rapid conversion of NiFe double hydroxide into metallic NiFeP using PH3 plasma treatment and further construction of amorphous NiFe hydroxides/NiFeP/Ni foam as efficient and stable oxygen-evolving anodes.
Abstract: Water splitting driven by electricity or sunlight is one of the most promising ways to address the global terawatt energy needs of future societies; however, its large-scale application is limited by the sluggish kinetics of the oxygen evolution reaction (OER). NiFe-based compounds, mainly oxides and hydroxides, are well-known OER catalysts and have been intensively studied; however, the utilization of the synergistic effect between two different NiFe-based materials to further boost the OER performance has not been achieved to date. Here, we report the rapid conversion of NiFe double hydroxide into metallic NiFeP using PH3 plasma treatment and further construction of amorphous NiFe hydroxide/NiFeP/Ni foam as efficient and stable oxygen-evolving anodes. The strong electronic interactions between NiFe hydroxide and NiFeP significantly lower the adsorption energy of H2O on the hybrid and thus lead to enhanced OER performance. As a result, the hybrid catalyst can deliver a geometrical current density of 300 ...

477 citations


Journal ArticleDOI
TL;DR: In this paper, a compositional engineering approach via incorporating Bi3+ in CsPbI3 to stabilize the α-phase at room temperature was introduced, which achieved a high PCE of 13.21% at an optimal condition (incorporation of 4 mol % Bi3+) and maintain 68% of the initial PCE for 168 h under ambient conditions without encapsulation.
Abstract: All-inorganic CsPbI3 perovskite is emerging to be an alternative light-harvesting material in solar cells owing to the enhanced stability and comparable photovoltaic performance compared to organic–inorganic hybrid perovskites. However, the desirable black phase α-CsPbI3 is not stable at room temperature and degrades rapidly to a nonperovskite yellow phase δ-CsPbI3. Herein, we introduce a compositional engineering approach via incorporating Bi3+ in CsPbI3 to stabilize the α-phase at room temperature. Fully inorganic solar cells based on the Bi-incorporated α-CsPb1–xBixI3 compounds demonstrate a high PCE of 13.21% at an optimal condition (incorporation of 4 mol % Bi3+) and maintain 68% of the initial PCE for 168 h under ambient conditions without encapsulation. This is the first attempt of partial substitution of the “B”-site of the perovskite to stabilize the α-CsPbI3, which paves the way for further developments of such perovskites and other optoelectronic devices.

436 citations


Journal ArticleDOI
TL;DR: It is proposed that an emphasis on purely performance-based metrics has diluted the community’s understanding of why a certain methodology is (un)successful and the need for more consistent and fundamental research on the interfacial electrochemistry on Li metal anodes is motivated.
Abstract: Li metal anodes are often considered a “holy grail” in the field of rechargeable batteries. Accordingly, the research community continuously seeks new strategies to improve their cyclability and reduce interfacial degradation. However, many recent reports focus on approaches that mitigate the symptoms of poor performance due to dendrites without addressing the underlying root cause of why they form and how they evolve. We propose that an emphasis on purely performance-based metrics has diluted the community’s understanding of why a certain methodology is (un)successful. Furthermore, the lack of consistent protocols for reporting cell performance and inconsistent terminology for describing physical phenomena that occur at the Li anode make quantitative comparison difficult. The goal of this Perspective is to motivate the need for more consistent and fundamental research on the interfacial electrochemistry on Li metal anodes. Herein we provide an overview of: 1) recent advances in understanding the fundamen...

Journal ArticleDOI
TL;DR: In this paper, it was shown that ion segregation takes place via halide defects, resulting in iodide-rich lowbandgap regions close to the illuminated surface of the film, driven by the strong gradient in carrier generation rate through the thickness of these strongly absorbing materials.
Abstract: Solution-processable metal halide perovskites show immense promise for use in photovoltaics and other optoelectronic applications. The ability to tune their bandgap by alloying various halide anions (for example, in CH3NH3Pb(I1–xBrx)3, 0 < x < 1) is however hampered by the reversible photoinduced formation of sub-bandgap emissive states. We find that ion segregation takes place via halide defects, resulting in iodide-rich low-bandgap regions close to the illuminated surface of the film. This segregation may be driven by the strong gradient in carrier generation rate through the thickness of these strongly absorbing materials. Once returned to the dark, entropically driven intermixing of halides returns the system to a homogeneous condition. We present approaches to suppress this process by controlling either the internal light distribution or the defect density within the film. These results are relevant to stability in both single- and mixed-halide perovskites, leading the way toward tunable and stable p...

Journal ArticleDOI
TL;DR: In this paper, the authors outline the technology timeline and characteristics of the most promising catalysts currently being developed and discuss the remaining challenges for both platinum group metal and nonprecious metal catalysts.
Abstract: Proton exchange membrane fuel cells (PEMFCs) have already penetrated many commercial markets (e.g., portable power, backup power, materials handling, and buses) and are poised to greatly expand in the automotive market with both Toyota and Hyundai recently commercializing small fleets. As this occurs, catalysts for PEMFCs will experience ever greater demands on cost, activity, and durability. This Perspective outlines the technology timeline and characteristics of the most promising catalysts currently being developed and discusses the remaining challenges for both platinum group metal and nonprecious metal catalysts. Finally, the importance of combined catalyst and catalyst layer design strategies is highlighted, and a brief discussion on the future outlook of this field is provided.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate an aqueous organic and organometallic redox flow battery utilizing reactants composed of only earth-abundant elements and operating at neutral pH.
Abstract: We demonstrate an aqueous organic and organometallic redox flow battery utilizing reactants composed of only earth-abundant elements and operating at neutral pH. The positive electrolyte contains bis((3-trimethylammonio)propyl)ferrocene dichloride, and the negative electrolyte contains bis(3-trimethylammonio)propyl viologen tetrachloride; these are separated by an anion-conducting membrane passing chloride ions. Bis(trimethylammoniopropyl) functionalization leads to ∼2 M solubility for both reactants, suppresses higher-order chemical decomposition pathways, and reduces reactant crossover rates through the membrane. Unprecedented cycling stability was achieved with capacity retention of 99.9943%/cycle and 99.90%/day at a 1.3 M reactant concentration, increasing to 99.9989%/cycle and 99.967%/day at 0.75–1.00 M; these represent the highest capacity retention rates reported to date versus time and versus cycle number. We discuss opportunities for future performance improvement, including chemical modification...

Journal ArticleDOI
TL;DR: In this paper, the authors showed that in low-dimensional perovskites both in the dark and under illumination, an indication of better stability of these materials for solar cells and light-emitting diodes.
Abstract: Ion migration, which occurs in regular three-dimensional perovskites, is shown to be suppressed in low-dimensional perovskites both in the dark and under illumination, an indication of better stability of these materials for solar cells and light-emitting diodes.

Journal ArticleDOI
TL;DR: In this article, the authors focused on the journey of Mn doping from group II-VI semiconductors to lead halide polysilicon and perovskite host nanocrystals.
Abstract: Mn2+ ions doped in high-energy absorbing semiconductor host nanocrystals take away the exciton energy and result in spin-polarized d–d emission. For the last three decades this has been widely studied on group II–VI semiconductors. Recently, the doping has been extended to CsPbX3 perovskite nanocrystals. Although the optical transition follows a similar principle, in which the exciton energy is transferred to dopant Mn d-state, doping in perovskite also revealed several new fundamental aspects of doping and dopant-induced new optical properties. Here, anions which mostly tune the band gap controlled the fate of the appearance of Mn emission. Also, the doping process was observed to be different than traditional growth doping. Hence, in perovskite host nanocrystals, while some aspects of Mn doping are found to be in agreement with previous findings, some new facts also surfaced. Combining all these facts, this Perspective focuses on the journey of Mn doping from group II–VI semiconductors to lead halide pe...

Journal ArticleDOI
TL;DR: In this paper, the authors reported the highly stable galvanostatic cycling of Li electrodes in a symmetric Li|electrolyte solution|Li coin-cell configuration at a high rate and high areal capacity using fluoroethylene carbonate (FEC)-based electrolyte solutions.
Abstract: We report the highly stable galvanostatic cycling of lithium metal (Li) electrodes in a symmetrical Li|electrolyte solution|Li coin-cell configuration at a high rate and high areal capacity using fluoroethylene carbonate (FEC)-based electrolyte solutions [1 M LiPF6 in FEC/dimethyl carbonate (DMC)]. The FEC-based electrolyte solution shows cycling behavior that is markedly better than that observed for the cells cycled with an ethylene carbonate (EC)-based electrolyte solution (1 M LiPF6 in EC/DMC). With FEC-based electrolyte solution, Li|Li cells can be cycled at 2 mA cm–2 with an areal capacity of 3.3 mAh cm–2 for more than 1100 cycles, and full Li|LiNi0.6Co0.2Mn0.2O2 (NMC) cells with high areal loading cathode demonstrate stable cycling with the same capacity during 90 cycles. An increase in areal capacity up to 6 mA h cm–2 does not affect the shape of the voltage profile of the symmetric Li|Li cells. The reason for this high performance is the formation of a stable and efficient solid electrolyte inter...


Journal ArticleDOI
TL;DR: In this article, the authors present a short overview and key results of a systematic study of the application of one of the recently most widely investigated components of the electrolyte solutions for lithium-ion batteries, namely, fluoroethylene carbonate (FEC).
Abstract: The performance of lithium-ion batteries (LIBs) depends critically on the nature of the solid–electrolyte interphase (SEI) layers formed on their electrodes surfaces, which are, in turn, defined by the composition of the electrolyte solution. Here, we present a short overview and key results of a systematic study of the application of one of the recently most widely investigated components of the electrolyte solutions for LIBs, namely, fluoroethylene carbonate (FEC). We discuss the benefits of FEC-based electrolyte solutions over the most commonly used ethylene carbonate (EC)-based electrolyte solutions for different LIB systems, including the high-capacity Si anode, high-voltage LiCoPO4 and LiNi0.5Mn1.5O4, Li–sulfur, and other cathodes, as well as full Li-ion cells. Special emphasis is given to the composition and properties of the SEI that is formed on the surface of anodes and cathodes as a result of the electrochemical reduction/oxidation of FEC.

Journal ArticleDOI
TL;DR: Low-dimensional-networked (low-DN) perovskite derivatives are bulk quantum materials in which charge carriers are localized within ordered metal halide sheets, rods, or clusters that are separated by cationic lattices.
Abstract: Low-dimensional-networked (low-DN) perovskite derivatives are bulk quantum materials in which charge carriers are localized within ordered metal halide sheets, rods, or clusters that are separated by cationic lattices. After two decades of hibernation, this class of semiconductors reemerged in the past two years, largely catalyzed by the interest in alternative, more stable absorbers to CH3NH3PbI3-type perovskites in photovoltaics. Whether low-DN perovskites will surpass other photovoltaic technologies remains to be seen, but their impressively high photo- and electroluminescence yields have already set new benchmarks in light emission applications. Here we offer our perspective on the most exciting advances in materials design of low-DN perovskites for energy- and optoelectronic-related applications. The next few years will usher in an explosive growth in this tribe of quantum materials, as only a few members have been synthesized, while the potential library of compositions and structures is believed to...

Journal ArticleDOI
TL;DR: In this article, a room-temperature synthesis was employed to prepare the platelets with thickness 2.2 nm (4 monolayers), which is significantly smaller than the Bohr excitonic diameter of CsPbCl3 (5 nm).
Abstract: Strong quantum confinement in Mn-doped semiconductor nanocrystals enhances dopant–carrier exchange interactions. Here, we report the synthesis and optical properties of strongly quantum confined, quasi two-dimensional, Mn-doped CsPbCl3 nanoplatelets. A room-temperature synthesis was employed to prepare the platelets with thickness 2.2 nm (4 monolayers), which is significantly smaller than the Bohr excitonic diameter of CsPbCl3 (5 nm). Efficient transfer of excitonic energy from the host to the Mn2+ dopant ions leads to a spin-forbidden 4T1–6A1 Mn d-electron emission with the highest quantum yield of ∼20% and exhibits a long lifetime of 1.6 ms. Subsequent anion exchange reactions at room temperature lead to the formation of Mn-doped CsPbBr3 nanoplatelets, with weak Mn emission. These newly developed Mn-doped cesium lead halide nanoplatelets are suitable candidates for exploring the effects of quantum confinement on dopant–carrier exchange interaction and exhibiting interesting magneto-optic properties.

Journal ArticleDOI
TL;DR: In this paper, the recent development of a variety of Redox-Active Organic Materials (ROMs) and associated battery designs in both aqueous and nonaqueous electrolytes are reviewed.
Abstract: Redox flow batteries (RFBs) are propitious stationary energy storage technologies with exceptional scalability and flexibility to improve the stability, efficiency, and sustainability of our power grid. The redox-active materials are the key component for RFBs with which to achieve high energy density and good cyclability. Traditional inorganic-based materials encounter critical technical and economic limitations such as low solubility, inferior electrochemical activity, and high cost. Redox-active organic materials (ROMs) are promising alternative “green” candidates to push the boundaries of energy storage because of the significant advantages of molecular diversity, structural tailorability, and natural abundance. Here, the recent development of a variety of ROMs and associated battery designs in both aqueous and nonaqueous electrolytes are reviewed. The critical challenges and potential research opportunities for developing practically relevant organic flow batteries are discussed.

Journal ArticleDOI
TL;DR: In this paper, the authors describe the dynamics and energy distribution of the charge carriers produced by photon absorption and the implications for the photocatalysis mechanism, and discuss how spectroscopy can be used to provide insight into the coupling between plasmons and molecular resonances.
Abstract: Metal nanoparticles are excellent light absorbers. The absorption processes create highly excited electron–hole pairs, and recently there has been interest in harnessing these hot charge carriers for photocatalysis and solar energy conversion applications. The goal of this Perspective is to describe the dynamics and energy distribution of the charge carriers produced by photon absorption and the implications for the photocatalysis mechanism. We will also discuss how spectroscopy can be used to provide insight into the coupling between plasmons and molecular resonances. In particular, the analysis shows that the choice of material and shape of the nanocrystal can play a crucial role in hot electron generation and coupling between plasmons and molecular transitions. The detection and even calculation of many-body hot-electron processes in the plasmonic systems with continuous spectra of electrons and short lifetimes are challenging, but at the same time they are very interesting from the points of view of b...

Journal ArticleDOI
TL;DR: In this article, the electrical resistivity and the moisture stability of two-dimensional Ruddlesden-Popper (CH3(CH2)3NH3)2(CH3NH 3)n−1SnnI3n+1 perovskites are considerably improved compared to those of the three-dimensional (3D) CH 3NH3SnI3 perovsite and subsequently show the solar cell fabrication using a simple one-step spincoating method.
Abstract: Low electrical resistivity (high dark carrier concentration) of CH3NH3SnI3 often leads to short-circuiting in solar cells, and appropriate thin-film modifications are required to ensure functional devices. The long-term durability of organic–inorganic perovskite solar cells necessitates the protection of perovskite thin films from moisture to prevent material decomposition. Herein, we report that the electrical resistivity and the moisture stability of two-dimensional (2D) Ruddlesden–Popper (CH3(CH2)3NH3)2(CH3NH3)n−1SnnI3n+1 perovskites are considerably improved compared to those of the three-dimensional (3D) CH3NH3SnI3 perovskite and subsequently show the solar cell fabrication using a simple one-step spin-coating method. These 2D perovskites are semiconductors with optical band gaps progressively decreasing from 1.83 eV (n = 1) to 1.20 eV (n = ∞). The n = 3 and n = 4 members with optimal band gaps of 1.50 and 1.42 eV for solar cells, respectively, were thus chosen for in-depth studies. We demonstrate th...

Journal ArticleDOI
TL;DR: In this article, the authors identify reaction products and elucidate the oxidation mechanism of both ASnI3 and ASn0.5Pb 0.5I3 (where A can be made of methylammonium, formamidinium, cesium, or a combination of these) perovskites.
Abstract: The recent development of efficient binary tin- and lead-based metal halide perovskite solar cells has enabled the development of all-perovskite tandem solar cells, which offer a unique opportunity to deliver high performance at low cost. Tin halide perovskites, however, are prone to oxidation, where the Sn2+ cations oxidize to Sn4+ upon air exposure. Here, we identify reaction products and elucidate the oxidation mechanism of both ASnI3 and ASn0.5Pb0.5I3 (where A can be made of methylammonium, formamidinium, cesium, or a combination of these) perovskites and find that substituting lead onto the B site fundamentally changes the oxidation mechanism of tin-based metal halide perovskites to make them more stable than would be expected by simply considering the decrease in tin content. This work provides guidelines for developing stable small band gap materials that could be used in all-perovskite tandems.

Journal ArticleDOI
TL;DR: In this paper, a mesoscopic perovskite solar cell using CsPb0.98Sr0.02I2Br achieves a stabilized efficiency at 10.8%.
Abstract: Cesium (Cs) metal halide perovskites for photovoltaics have gained research interest due to their better thermal stability compared to their organic–inorganic counterparts. However, demonstration of highly efficient Cs-based perovskite solar cells requires high annealing temperature, which limits their use in multijunction devices. In this work, low-temperature-processed cesium lead (Pb) halide perovskite solar cells are demonstrated. We have also successfully incorporated the less toxic strontium (Sr) at a low concentration that partially substitutes Pb in CsPb1–xSrxI2Br. The crystallinity, morphology, absorption, photoluminescence, and elemental composition of this low-temperature-processed CsPb1–xSrxI2Br are studied. It is found that the surface of the perovskite film is enriched with Sr, providing a passivating effect. At the optimal concentration (x = 0.02), a mesoscopic perovskite solar cell using CsPb0.98Sr0.02I2Br achieves a stabilized efficiency at 10.8%. This work shows the potential of inorgani...

Journal ArticleDOI
TL;DR: The perovskite cells are a promising new material for low-cost, high-efficiency photovoltaics as discussed by the authors, however, there remains uncertainty as to whether materials with the required stability can be found within the associated material system and whether the presence of Pb in highly soluble form will limit commercial application.
Abstract: One of the most exciting developments in photovoltaics over recent years has been the emergence of organic–inorganic lead halide perovskites as a promising new material for low-cost, high-efficiency photovoltaics. In record time, confirmed laboratory energy conversion efficiencies have increased from a few percent to over 22%. Although there remains uncertainty as to whether materials with the required stability can be found within the associated material system and whether the presence of Pb in highly soluble form will limit commercial application, it is certain that these perovskite cells will remain the focus of concerted research efforts over the coming decade. The early history of the development of this technology leading to the first perovskite cells is documented as are significant recent developments.

Journal ArticleDOI
TL;DR: In this Perspective, views on improving this emerging battery system by nanoscience are shown on rational design of the solid-state Li metal battery for optimized performance.
Abstract: Driven by an increasing demand on storage devices with higher energy outputs and better safety, solid-state lithium metal batteries have shown their potential to replace the traditional liquid-based Li-ion batteries and power the future storage market. In this Perspective, we will show our views on improving this emerging battery system by nanoscience. Discussions will be placed, from both scientific and engineering points of view, on the fundamentals and problems of the battery and its key components. The corresponding “nano” strategies will also be addressed, as well as recent progress in related fields including materials synthesis, battery design, and characterization techniques. With these efforts, we want to provide insights on rational design of the solid-state Li metal battery for optimized performance.

Journal ArticleDOI
TL;DR: All alloyed CsPbxMn1–xI3 nanocrystals have essentially the same optical features and crystal structure as the parent α-CsPbI3 system, but they are stable in films and in solution for periods over a month.
Abstract: CsPbI3 nanocrystals are still limited in their use because of their phase instability as they degrade into the yellow nonemitting δ-CsPbI3 phase within a few days. We show that alloyed CsPbxMn1–xI3 nanocrystals have essentially the same optical features and crystal structure as the parent α-CsPbI3 system, but they are stable in films and in solution for periods over a month. The stabilization stems from a small decrease in the lattice parameters slightly increasing the Goldsmith tolerance factor, combined with an increase in the cohesive energy. Finally, hybrid density functional calculations confirm that the Mn2+ levels fall within the conduction band, thus not strongly altering the optical properties.

Journal ArticleDOI
TL;DR: The origin of nonradiative decay in metal halide perovskites is still poorly understood as discussed by the authors, and the authors highlight key observations of these parasitic pathways on both the macro and microscale in thin films and full devices.
Abstract: Metal halide perovskites are generating enormous interest for their use in solar cells and light-emission applications One property linking the high performance of these devices is a high radiative efficiency of the materials; indeed, a prerequisite for these devices to reach their theoretical efficiency limits is the elimination of all nonradiative decay Despite remarkable progress, there exists substantial parasitic nonradiative recombination in thin films of the materials and when interfaced into devices, and the origin of these processes is still poorly understood In this Perspective, I will highlight key observations of these parasitic pathways on both the macro- and microscale in thin films and full devices I will summarize our current understanding of the origin of nonradiative decay, as well as existing solutions that hint at facile ways to remove these processes I will also show how these nonradiative decay pathways are intimately related to ionic migration, leading to the tantalizing conclu