Perovskites: crystal structure, important compounds and properties Peng Gao GMF Group Meeting 12,04,2016 Solar energy resource PV instillations Global Power Demand Terrestrial sun light To start • We have to solve the energy problem. • Any technology that has good potential to cut carbon emissions by > 10 % needs to be explored aggressively. • Researchers should not be deterred by the struggles some companies are having. • Someone needs to invest in scaling up promising solar cell technologies. Origin And History of Perovskite compounds Perovskite is calcium titanium oxide or calcium titanate, with the chemical formula CaTiO3. The mineral was discovered by Gustav Rose in 1839 and is named after Russian mineralogist Count Lev Alekseevich Perovski (1792–1856).” All materials with the same crystal structure as CaTiO3, namely ABX3, are termed perovskites: Origin And History of Perovskite compounds Very stable structure, large number of compounds, variety of properties, many practical applications. Key role of the BO6 octahedra in ferromagnetism and ferroelectricity. Extensive formation of solid solutions material optimization by composition control and phase transition engineering. A2+ B4+ O2- Ideal cubic perovskite structure (ABO3) Classification of Perovskite System Perovskite Systems Inorganic Halide Oxide Perovskites Perovskites Alkali-halide Organo-Metal Intrinsic Doped Perovskites Halide Perovskites Perovskites A2Cl(LaNb2)O7 Perovskites 1892: 1st paper on lead halide perovskites Structure deduced 1959: Kongelige Danske Videnskabernes Selskab, Matematisk-Fysike Meddelelser (1959) 32, p1-p17 Author: Moller, C.K. Title: The structure of cesium plumbo iodide CsPbI3 Useful salts with perovskite structure Reference Properties Existing and potential Notes compound applications Ferroelectricity, piezoelectricity, high dielectric constant Multilayer ceramic capacitors (MLCCs), Most widely used dielectric ceramic BaTiO3 PTCR resistors, embedded capacitance TC = 125°C Non-linear dielectric properties Tunable microwave devices Used in the paraelectric state (Ba,Sr)TiO3 Ferroelectricity, piezoelectricity Piezoelectric transducers and actuators, PZT: most successful piezoelectric Pb(Zr,Ti)O3 ferroelectric memories (FERAMs) material Ferroelectric with high Curie temperature High-temperature actuators, FeRAMs Aurivillius compound Bi4Ti3O12 TC = 675°C Ferroelectricity, piezoelectricity Lead-free piezoceramics Performances not yet comparable to (K0.5Na0.5)NbO3, PZT but rapid progress Na0.5Bi0.5TiO3 Transparent ferroelectric Optoelectronic devices First transparent ferroelectric ceramic (Pb,La)(Ti,Zr)O3 Magnetoelectric coupling, high Curie temperature Magnetic field detectors, Most investigated multiferroic BiFeO3 memories compound. TC = 850°C Relaxor ferroelectric Capacitors, actuators High permittivity, large electrostrictive PbMg1/3Nb2/3O3 coefficients, frequency-dependent properties Ferromagnetism Electrode material for epitaxial ferroelectric SrRuO3 thin films Ferromagnetism, giant magnetoresistance, spin- Magnetic field sensors, spin electronic (La, A)MnO3 A = Ca, Sr, Ba polarized electrons devices Incipient ferroelectricity, thermoelectric power, metallic Alternative gate dielectric material, barrier Multifunctional material SrTiO3 electronic conduction when n-doped, mixed layer capacitors, substrate for epitaxial conduction when p-doped, photocatalyst growth, photoassisted water splitting Oxyde-ion conduction Electrolyte in solid oxide fuel cells (SOFCs) BaIn O is an oxygen deficient LaGaO3 2 5 perovskite with brownmillerite structure. BaIn2O5 Proton conduction Electrolyte in protonic solid oxide fuel cells (P- High protonic conduction at 500- BaCeO3, BaZrO3 SOFCs) 700°C Mixed conduction, catalyst Cathode material in SOFCs, oxygen Used for SOFC cathodes (La,Sr)BO3 (B = Mn, Fe, Co) separation membranes, membrane reactors, controlled oxidation of hydrocarbons, Host materials for rare-earth luminescent ions, Lasers LaAlO3 Substrates for epitaxial film deposition YAlO3 Early publications on lead halide perovskites 1st Solar Cell Reports Solid-State DSC DSSC using redox electrolyte DSSC using hole transport material Redox electrolyte Solid hole conductor PCE PCE light harvester dye dye or pigment film TiO2 TiO2 Evolution of device structures Various device fabrication methods ‘Anti-solvent’ the key to optimum morphology a) N. J. Jeon, J. H. Noh, Y. C. Kim, W. S. Yang, S. Ryu, S. I. Seok, Nat Mater 2014, 13, 897-903. b) M. Xiao, F. Huang, W. Huang, Y. Dkhissi, Y. Zhu, J. Etheridge, A. Gray-Weale, U. Bach, Y.-B. Cheng, L. Spiccia, Angew. Chemie Int. Ed. 2014, 53, 9898–9903. Perovskite vs silicon technology Production of silicon and silicon wafers Expensive, high-energy process, generating high levels of waste material Production of perovskite cell Simpler, lower cost, lower embodied energy, massively reduced environmental impact Toxicity Medium Medium Low High Abundance Low Low High High Low Bandgap – q·Voc Loss in Perovskite Solar Cells Material Bandgap (eV) q·Voc (eV) Energy loss (eV) GaAs 1.43 1.12 0.31 Silicon 1.12 0.75 0.37 CIGS ~1.15 0.74 0.41 Perovskite 1.55 1.07 0.48 (CH3NH3PbI3) CdTe 1.49 0.90 0.59 a-Silicon 1.55 0.89 0.66 M. Green et al. Solar cell efficiency tables (version 42) July 2013 The hybride Perovskite is a Strongly-Absorbing Direct Band Gap Semiconductor The Perovskite Bandgap can be tuned by Chemical Substitution The band gap can be tuned from 1.57 eV to 2.23 eV by substituting bromine for iodine in CH3NH3Pb(BrxI1-x)3 For hybrid But the morphology is not stable! tandem with CIGS eV Noh et al., Nano Lett. 2013 Lead-free: CH3NH3SnI3 Perovskite Tuning the structure of perovskites from 3D to 2D • When will a 3D perovskite form? • When the A, B and X components fit together neatly in the crystal lattice. • Assuming ionic radii of RA etc, For a close packed cubic perovskite the structure is possible, provided: Low dimensional perovskite with more possibilities The basic structures of 2D organic–inorganic perovskite with bilayer and single layer intercalated organic molecules Schematic representations of hydrogen-bond styles between + NH3 heads with an inorganic framework <110> oriented 2D organic-inorganic hybrid perovskite <110>-oriented (C6H13N3)PbBr4 (API-PbBr4) that is prepared by reacting N-(3-amino- propyl)imidazole (API) with PbBr2 in hydrobromic acid. 5,5’-bis(2-aminoethyl)-2,2’:5’,2’:5’,2’-quaterthiophene (AEQT) based 2D organic-inorganic hybrid perovskite Cl Br l Room temperature photoluminescence excitation (λem = 540 nm) and emission (λex = 370 nm) spectra for thermally ablated thin films of (AEQT)PbX4 with (a) X = Cl and (b) X 10.1021/ic991048k = I. Polymerization within the organic layer of perovskite structures 6-amino-2,4-trans,trans-hexadienoic acid, within a cadmium (II) chloride perovskite framework, polymerizes under ultraviolet (UV) irradiation. More rigid and stable perovskite structure! B. Tieke and G. Chapuis, Mol. Cryst. Liq. Cryst., 1986, 137, 101 Ni(bipy)3 as cations for 2D perovskite as hybrid magnetic semiconductor 10.1016/j.jssc.2007.10.010 Take home message • Being toxic and instable, Lead-Halide perovskite is an excellent ‘MODLE’ material for electronic application. • 3D type , Lead-Halide perovskite has found prevailing application in PV field. • 3D type , Lead-Halide perovskite can be strong competitor to silicon PV • 2D or 1D type perovskite provide more possibility for more broad applications. References 1. Band alignment of the hybrid halide perovskites CH3NH3PbCl3, CH3NH3PbBr3 and CH3NH3PbI3 2. Keith T. Butler, Jarvist M. Frost and Aron Walsh 3. Recent progress in efficient hybrid lead halide perovskite solar cells – Jin Cui, Hualiang Yuan, Hong Lin et;al. 4. Crystallography and Chemistry of Perovskites Mats Johnsson and Peter Lemmens (Dept. Inorg. Chemistry, Stockholm University) 5. Perovskite Solar cells: An emerging photovoltaic technology Nam-Gyu Park (SKKU) 6. Perovskite Solar Cells: Film Formation and properties- Tze Bin Song, Qi Chen, Huanping Zhou, et al. 7. www.solarpowerworldonline.com/2015/04/the-perfect-marriage-silicon-and-perovskite-solar-cells/ 8. Lead-free organic–inorganic tin halide perovskites for photovoltaic applications -Nakita K. Noel, Samuel D. Stranks, Antonio Abate, Christian Wehrenfennig, Simone Guarnera, Amir-Abbas Haghighirad, Aditya Sadhanala, Giles E. Eperon, Sandeep K. Pathak, Michael B. Johnston, Annamaria Petrozza, Laura M. Herza and Henry J. Snaith 9. A Layered Hybrid Perovskite Solar-Cell Absorber with Enhanced Moisture Stability-Ian C. Smith, Eric T. Hoke, Diego Solis-Ibarra, Michael D. McGehee, and Hemamala I. Karunadasa Thank you for your attention!.