The making of a reconfigurable semiconductor with a soft ionic lattice

Rapid synthetic advancements in halide perovskites have spurred a growing family of new compositions, crystal structures, and properties. The facile synthesis can be attributed to the soft flexible lattice perovskites, property that yields low-temperature synthesis, mobile ions, easily configurable structures. However, order achieve products with controlled properties, there must exist design principle unites physical chemistry theories advanced is presently absent from existing literature. This perspective examines advances, limitations, understanding call for such perovskite nanostructures. future directions outlined this present guiding principles next generations nanostructures functional stability, complexity fundamental studies device applications. Furthermore, framework presented may also applied more generally other semiconducting materials lattices. Synthetic crucial designing properties paving ways create With expanding approaches, it especially necessary elucidate formation how influences their associated inform unifying principle. In perspective, we summarize key milestones community inorganic highlight reaction kinetics thermodynamics distinguish them traditional semiconductors. We then retrospective view conceptually address lingering questions field along possible solutions. aims articulate relation between structural tunability, environmental stability provide an outlook efficient stable devices. IntroductionHalide achieved remarkable optoelectronic performance over past decade, notable applications solar cells, light-emitting diodes (LEDs), lasers,1Green M.A. Ho-Baillie A. Snaith H.J. emergence cells.Nat. Photonics. 2014; 8: 506-514https://doi.org/10.1038/nphoton.2014.134Google Scholar, 2Sutherland B.R. Sargent E.H. Perovskite photonic sources.Nat. 2016; 10: 295-302https://doi.org/10.1038/nphoton.2016.62Google 3Eaton S.W. Lai M. Gibson N.A. Wong A.B. Dou L. Ma J. Wang L.-W. Leone S.R. Yang P. Lasing robust cesium lead nanowires.Proc. Natl. Acad. Sci. 113: 1993-1998https://doi.org/10.1073/pnas.1600789113Google 4Zhu H. Fu Y. Meng F. Wu X. Gong Z. Ding Q. Gustafsson M.V. Trinh M.T. Jin S. Zhu X.-Y. Lead nanowire lasers low lasing thresholds high quality factors.Nat. Mater. 2015; 14: 636-642https://doi.org/10.1038/nmat4271Google Scholar because solution processability, ease fabrication, extraordinary has produced nanoscale macroscale across dimensionality, composition, further diversifying prompting probe class semiconductor. As closely governs final goes without saying comprehensive pathways crucial.All-inorganic gained special attention due enhanced hybrid perovskites. Since first nanocrystal reports all-inorganic perovskites,5Protesescu Yakunin Bodnarchuk M.I. Krieg Caputo R. Hendon C.H. R.X. Walsh Kovalenko Nanocrystals Cesium Halide Perovskites (CsPbX 3, X = Cl, Br, I): Novel Optoelectronic Materials Showing Bright Emission Wide Color Gamut.Nano Lett. 15: 3692-3696https://doi.org/10.1021/nl5048779Google 6Zhang D. Eaton Yu Solution-Phase Synthesis Nanowires.J. Am. Chem. Soc. 137: 9230-9233https://doi.org/10.1021/jacs.5b05404Google 7Bekenstein Koscher B.A. Alivisatos A.P. Highly Luminescent Colloidal Nanoplates Their Oriented Assemblies.J. 16008-16011https://doi.org/10.1021/jacs.5b11199Google synthesis-related covered almost every domain nanostructure engineering, including size morphology control, ion exchange, chemical doping, heterostructures, ligand structure evolution. Although review papers various lengths topics are abundant literature,8Akkerman Q.A. Rainò G. Manna Genesis, challenges opportunities colloidal nanocrystals.Nat. 2018; 17: 394-405https://doi.org/10.1038/s41563-018-0018-4Google 9Shamsi Urban A.S. Imran De Trizio Metal Nanocrystals: Synthesis, Post-Synthesis Modifications, Optical Properties.Chem. Rev. 2019; 119: 3296-3348https://doi.org/10.1021/acs.chemrev.8b00644Google 10Dey Ye Debroye E. Ha S.K. Bladt Kshirsagar Yin et al.State Art Prospects Nanocrystals.ACS Nano. 2021; 10775-10981https://doi.org/10.1021/acsnano.0c08903Google general coherently incorporates methods, characterization tools still missing. A starting point addressing conceptual task difference covalent semiconductors (Table 1; Figures 1A 1B ), fact ionic crystals lower cohesive energies compared (2–3 eV per atom typical but >4 as Si).11Ozen Iyikanat Ozcan Tekneci G.E. Eren I. Sozen Sahin Orthorhombic CsPbI3 perovskites: Thickness-dependent structural, optical vibrational properties.Comput. Condens. Matter. 2020; 23e00453https://doi.org/10.1016/j.cocom.2019.e00453Google Scholar,12Dolocan V. Dolocan V.O. Relation inter-atomic forces solids bulk modulus, energy thermal expansion.Mod. Phys. B. 2008; 22: 2481-2492https://doi.org/10.1142/S0217984908017096Google comparison only superficially useful if not viewed through integrated where ideas structure, on equal footing. uniqueness its origin bonding framework, which impart flexibility long-term instabilities. Addressing remaining providing insights rational engineering require development, articulation experimental observations, perspectives open modifications light achievements.Table 1Comparative study conventional perovskitesConventional semiconductorsHalide perovskitesBulk propertiesBonding typecovalent, ionicionicCohesive energy>4 eV/atom3 eV/atomMelting pointabove 1,000°Cbelow 600°CSolubilityinsoluble solventssoluble polar solventsNanostructure propertiesSynthesis temperature (solution phase)above 300°Cbelow 150°CSynthesis (vapor phase)mostly above 1,000°C both evaporation deposition400°C–600°C evaporation;100°C–400°C depositionGrowth kineticsslowfast even at temperatureIncorporation organic componentsonly surface (nanocrystals)in (hybrid or 2D perovskite) (nanocrystals)Heterostructurecan interface another semiconductor by epitaxial growth when mismatch smallcan accommodate large mismatch; creation heterostructures post-synthesis Open table tab alignment Pieces Perspectives issue, divided into four sections. “past” section, emphasis “present” typically missing early “problems” raise community. Finally, “possibilities” attempt bridge gaps nanostructures.Past: Typical methodsIn 10 years, witnessed great advances particular, enormous scientific efforts been devoted nanocrystals, thin films, single crystals, heterostructures. focus methods crystalline heterostructure nanocrystals/microcrystals.Colloidal assistance capping ligands, produce ensemble uniform nanocrystals. Based similar hot-injection method borrowed II–VI quantum dots CsPbX3 nanocrystals distribution was reported 2015,5Protesescu and, since then, routes control morphology, size, facet exposure, phase composition developed (Figures 2A–2D ).8Akkerman Scholar,9Shamsi Scholar,20Bera Behera R.K. Pradhan N. ?-Halo Ketone Polyhedral Evolutions, Shape Conversions, Ligand Chemistry, Self-Assembly.J. 142: 20865-20874https://doi.org/10.1021/jacs.0c10688Google conditions resemble those following reveal distinct thermodynamic relatively temperature, dynamical shells.Figure 2Nanocrystal building blocks self-assemblyShow full caption(A–D) Colloidally synthesized cesium-lead-bromide nanocubes, rhombic dodecahedrons, nanowires, nanoplates, respectively, blocks.19Liu Siron Lu Dos Reis Cui Gao Lin Kong al.Self-Assembly Two-Dimensional Nanosheet Building Blocks Ordered Ruddlesden-Popper Phase.J. 141: 13028-13032https://doi.org/10.1021/jacs.9b06889Google 20Bera 21Gao Liu Louisia Zhang Nenon D.P. Scaling Laws Exciton Recombination Kinetics Low Dimensional Nanostructures.J. 8871-8879https://doi.org/10.1021/jacs.0c02000Google Copyright 2019 American Chemical Society.(E F) Self-assembly CsPbBr3 nanocubes simple-cubic superlattice.22Toso Baranov Altamura Scattarella Dahl Marras Singer Giannini C. al.Multilayer Diffraction Reveals That Superlattices Approach Structural Perfection Single Crystals.ACS 6243-6256https://doi.org/10.1021/acsnano.0c08929Google 2021 Society.(G H) nanoplates RP structures.19Liu Society.(I J) form binary ternary superlattices different types.23Cherniukh Stöferle T. Burian Travesset Naumenko Amenitsch Erni Mahrt R.F. al.Perovskite-type nanocubes.Nature. 593: 535-542https://doi.org/10.1038/s41586-021-03492-5Google Springer Nature.View Large Image Figure ViewerDownload Hi-res image Download (PPT)In contrast ligand-free solution-phase makes use substrate-assisted dissolution-recrystallization process.3Eaton film, acts precursor source nucleation sites, immersed diluted solution. dissolved precursors react slowly recrystallize perovskite. simple technique variety compositions nanostructured forms, CsPbBr3, CsPbI3, CsSnI3, alloys.3Eaton Scholar,24Lei Lee W. Electrical Tunability All-Inorganic Alloy Nanowires.Nano 18: 3538-3542https://doi.org/10.1021/acs.nanolett.8b00603Google Scholar,25Lai Bischak C.G. Ginsberg N.S. Structural, optical, electrical phase-controlled iodide nanowires.Nano Res. 2017; 1107-1114https://doi.org/10.1007/s12274-016-1415-0Google ScholarVapor-phase includes epitaxy, deposition, growth, provides route obtaining nanoscale/microscale films perovskites.26Chen Morrow D.J. Zheng Zhao Dang Stolt M.J. Kohler D.D. Czech K.J. al.Single-Crystal Thin Films Bromide Epitaxially Grown Oxide (SrTiO3).J. 139https://doi.org/10.1021/jacs.7b07506Google 27Wang Guan Li Cheng H.-C. Duan vapor deposition single-crystalline microplatelets applications.Nano 1223-1233https://doi.org/10.1007/s12274-016-1317-1Google 28Shoaib Zhou Xu Hu Fan al.Directional Growth Ultralong Nanowires High-Performance Photodetectors.J. 139https://doi.org/10.1021/jacs.7b08818Google 29Lu Xie Lei Kley C.S. Huang al.Giant Light-Emission Enhancement Surface Oxygen Passivation.Nano 6967-6973https://doi.org/10.1021/acs.nanolett.8b02887Google 30Zhang Quan L.N. Quantitative imaging anion exchange perovskites.Proc. 116: 12648 LP-12653https://doi.org/10.1073/pnas.1903448116Google 31Wang Jia S.-J. Atallah T.L. Caram J.R. Large-Area Patterning Heterostructures.Nano 21: 1454-1460https://doi.org/10.1021/acs.nanolett.0c04594Google semiconductors,32Jasinski J.M. Gates S.M. Silicon one step time: silicon hydride chemistry.Acc. 1991; 24: 9-15https://doi.org/10.1021/ar00001a002Google Scholar,33Huang M.H. Feick Tran Weber Catalytic zinc oxide nanowires transport.Adv. 2001; 13https://doi.org/10.1002/1521-4095Google vapor-phase requires temperatures via one-step transport (CVT) need additional reactive agents forming gaseous intermediates thanks volatile halogen elements end products. performed tube furnace27Wang chamber34Ma Wen Green A.W.Y. Hole Transport Layer Free Inorganic CsPbIBr 2 Solar Cell Dual Source Thermal Evaporation.Adv. Energy 6: 1502202https://doi.org/10.1002/aenm.201502202Google using either dual sources mixing appropriate stoichiometric ratios, under flow inert gas (Ar N2)29Lu Scholar,30Zhang Scholar,35Chen Samad Shen Guo Vapor-Phase Epitaxial Aligned Nanowire Networks (CsPbX3, I).Nano 460-466https://doi.org/10.1021/acs.nanolett.6b04450Google vacuum.31Wang Reports 5 years revealed dimensions, morphologies, phases pure well large-area films.26Chen Scholar,27Wang Scholar,29Lu dependence controllability choice substrate (e.g., epitaxy/non-epitaxy; mismatch-induced strain) important question investigated, chosen substrates (with structures parameters) greatly impact morphological band-gap modulation as-grown perovskites.Post-synthetic reactions, modify compositional, electronic, parent ABX3 exposed contains species (either phase), creating concentration gradient. gradient drives diffusion guest ions partial complete replacement anion. Notable examples reactions include tunable dimensionalities,7Bekenstein Scholar,36Nedelcu Protesescu Grotevent Fast Anion-Exchange 3 , 5635-5640https://doi.org/10.1021/acs.nanolett.5b02404Google 37Akkerman D’Innocenzo Accornero Scarpellini Petrozza Prato Tuning Properties Anion Exchange Reactions.J. 10276-10281https://doi.org/10.1021/jacs.5b05602Google 38Zhang Bekenstein Kornienko al.Synthesis Composition Tunable 138: 7236-7239https://doi.org/10.1021/jacs.6b03134Google well-defined separated sharp interfaces.18Dou Spatially resolved multicolor heterojunctions exchange.Proc. U. 114: 7216-7221https://doi.org/10.1073/pnas.1703860114Google Scholar,39Shi Yuan Shiring S.B. Akriti Su al.Two-dimensional lateral heterostructures.Nature. 580: 614-620https://doi.org/10.1038/s41586-020-2219-7Google cases direct difficult, post-synthetic make thermodynamically unstable nanostructures.38Zhang ScholarPresent: controlScientific development always linear process. simplistic detailing conceals complexities research iterative enterprise perplexities characteristics particular. To understand state field, extract literature anticipated semiconductors, derive better engineering.Figure 1 presents three-level account aiming topics. level, “synthesize” current paradigm within community, softness conception (gray-shaded boxes 1) followed discussion ensuing dynamic lattice, diffusivity, transition behaviors 1C–1F). last these 1G–1J).Soft perovskitesThroughout demonstrate directly related unique primary origins (1) molecular characteristics, (2) stereochemically active ns2 electron lone pairs Pb Sn atoms, (3) tolerance factor deviating unity reason instabilities—but geometrical might partially absorbed energetic consideration stabilized electrons.40Lee J.-H. Bristowe N.C. J.H. P.D. Cheetham A.K. Jang H.M. Resolving Physical Origin Octahedral Tilting Perovskites.Chem. 28: 4259-4266https://doi.org/10.1021/acs.chemmater.6b00968Google mechanism insight strategy, investigation essential.Ionic major interaction highly soluble most solvents thus processable. inversely scales ionicity,41Phillips J.C. Ionicity bond crystals.Rev. Mod. 1970; 42: 317-356https://doi.org/10.1103/RevModPhys.42.317Google melting points expected solid-state (Figure 1B). weak combined intrinsicall