A5043815603- Perovskite Materials and Applications
- Solid-state spectroscopy and crystallography
- Chalcogenide Semiconductor Thin Films
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Quantum Dots Synthesis And Properties
- Conducting polymers and applications
- Organic and Molecular Conductors Research
- Machine Learning in Materials Science
- Optical properties and cooling technologies in crystalline materials
- Advanced Thermoelectric Materials and Devices
- Photochemistry and Electron Transfer Studies
- Crystal Structures and Properties
- Gas Sensing Nanomaterials and Sensors
- Advanced Photocatalysis Techniques
- ZnO doping and properties
- Molecular Junctions and Nanostructures
- Organic Electronics and Photovoltaics
- Advanced Condensed Matter Physics
- Luminescence Properties of Advanced Materials
- Layered Double Hydroxides Synthesis and Applications
- Transition Metal Oxide Nanomaterials
- Thermal Expansion and Ionic Conductivity
Stanford University
2015-2023
SLAC National Accelerator Laboratory
2014-2021
Stanford Synchrotron Radiation Lightsource
2014-2021
Stanford Medicine
2018-2021
Menlo School
2015-2020
Harvard University
2011
Tin and lead iodide perovskite semiconductors of the composition AMX3, where M is a metal X halide, are leading candidates for high efficiency low cost tandem photovoltaics, in part because they have band gaps that can be tuned over wide range by compositional substitution. We experimentally identify two competing mechanisms through which A-site cation influences gap 3D halide perovskites. Using smaller distort lattice distinct ways: tilting MX6 octahedra or simply contracting isotropically....
This Perspective introduces the Harvard Clean Energy Project (CEP), a theory-driven search for next generation of organic solar cell materials. We give broad overview its setup and infrastructure, present first results, outline upcoming developments. CEP has established an automated, high-throughput, in silico framework to study potential candidate structures photovoltaics. The current project phase is concerned with characterization millions molecular motifs using first-principles quantum...
The recent development of efficient binary tin- and lead-based metal halide perovskite solar cells has enabled the all-perovskite tandem cells, which offer a unique opportunity to deliver high performance at low cost. Tin perovskites, however, are prone oxidation, where Sn2+ cations oxidize Sn4+ upon air exposure. Here, we identify reaction products elucidate oxidation mechanism both ASnI3 ASn0.5Pb0.5I3 (where A can be made methylammonium, formamidinium, cesium, or combination these)...
An overlooked factor affecting stability: the residual stresses in perovskite films, which are tensile and can exceed 50 MPa magnitude, a value high enough to deform copper, is reported. These provide significant driving force for fracture. Films shown be more unstable under stress—and conversely stable compressive stress—when exposed heat or humidity. Increasing formation temperature of films directly correlates with larger stresses, result thermal expansion coefficient perovskites....
Halide double perovskites have recently been developed as less toxic analogs of the lead perovskite solar-cell absorbers APbX3 (A = monovalent cation; X Br or I). However, all known halide large bandgaps that afford weak visible-light absorption. The first evaluated an absorber, Cs2AgBiBr6 (1), has a bandgap 1.95 eV. Here, we show dilute alloying decreases 1's by ca. 0.5 Importantly, time-resolved photoconductivity measurements reveal long-lived carriers with microsecond lifetimes in alloyed...
Organo-metal halide perovskites are an intriguing class of materials that have recently been explored for their potential in solar energy conversion. Within a very short period intensive research, highly efficient cell devices demonstrated. One the heavily debated questions this new field research concerns role chlorine solution-processed samples utilizing lead chloride and 3 equiv methylammonium iodide to prepare perovskite samples. We utilized combination X-ray photoelectron spectroscopy,...
Photoinduced halide segregation currently limits the perovskite chemistries available for use in high-bandgap semiconductors needed tandem solar cells. Here, we study impact of post-deposition surface modifications on photoinduced methylammonium lead mixed-halide perovskites. By coating a with electron-donating ligand trioctylphosphine oxide (TOPO), are able to both reduce nonradiative recombination and dramatically slow onset CH3NH3PbI2Br films. This result, coupled observation that rate...
We report the fabrication of monolithic all-perovskite tandem solar cells with a stabilized power conversion efficiency 19.1% and demonstrate improved thermal, atmospheric, operational stability tin–lead perovskite (FA<sub>0.75</sub>Cs<sub>0.25</sub>Sn<sub>0.5</sub>Pb<sub>0.5</sub>I<sub>3</sub>) used as low gap absorber.
Significant effort has focused on controlling the deposition of perovskite films to enable uniform films, enabling efficiencies climb dramatically. However, little attention been paid evolution thin-film stresses during and consequent effect film morphology. While a textured surface topology potential benefits for light scattering, smooth is desirable pinhole-free contact layers. We show that highly morphology made by popular antisolvent conversion methods arises because in-plane compressive...
Significance Hybrid organic–inorganic perovskites are a promising class of materials for efficient and low-cost solar cells. Unlike conventional inorganic semiconductors such as silicon gallium arsenide, hybrid feature significant dynamic disorder in their crystal structure. This can be broadly classified into lattice vibrations (phonons) molecular rotations. Phonons interact with charge carriers through electron–phonon coupling, which has substantial impacts on the operation Our study shows...
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTChlorine in PbCl2-Derived Hybrid-Perovskite Solar AbsorbersVanessa L. Pool†, Aryeh Gold-Parker†‡, Michael D. McGehee§, and F. Toney*†View Author Information† SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States‡ Department of Chemistry, Stanford University, 333 Campus Drive, Stanford, 94305, States§ Materials Science Engineering, 496 Lomita Mall, States*M. Toney. E-mail: [email protected]Cite...
Abstract Understanding the formation chemistry of metal halide perovskites is key to optimizing processing conditions and realizing enhanced optoelectronic properties. Here, we reveal structure crystalline precursor in methylammonium lead iodide (MAPbI 3 ) from single-step deposition chloride three equivalents (PbCl 2 + 3MAI) (MA = CH NH ). The as-spun film consists MA PbI Cl, which composed one-dimensional chains octahedra, coexisting with disordered MACl. We show that transformation into...
Sn alloying tunes a halide double perovskite to absorb visible light, in nontoxic composition.
With <italic>in situ</italic> ESEM and GIWAXS we saw that the perovskite degradation passes through hexagonal polytypes is dependent on composition.
Introducing heterovalent cations at the octahedral sites of halide perovskites can substantially change their optoelectronic properties. Yet, in most cases, only small amounts such metals be incorporated as impurities into three-dimensional lattice. Here, we exploit greater structural flexibility two-dimensional (2D) perovskite framework to place three distinct stoichiometric sites. The new layered AI 4[CuII(CuIInIII)0.5Cl8] (1, A = organic cation) may derived from a CuI-InIII double by...
We study the phase behavior of hybrid organic–inorganic metal-halide perovskite and propose a simple method to assess heterogeneity in <100 nm length scales.
We investigate the hypothesis of dynamic tetragonal domains occuring in cubic CH$_3$NH$_3$PbI$_3$ using high-resolution neutron spectroscopy to study a fully deuterated single crystal. The $\textit{R}$-point scattering above 327.5 K tetragonal-cubic phase transition is always resolution-limited energy and therefore inconsistent with domain predictions. This behavior instead consistent central peak phenomenon observed other perovskites. may originate from small, static, tetragonal-phase...
Tin-lead halide perovskites show promise as low- band gap absorbers to enable efficient all-perovskite tandem solar cells. While they have reached high efficiencies in single junction and cells, tin-containing face unique challenges- such a tendency degrade by oxidation of tin sometimes very short carrier lifetimes that limit diffusion lengths. We map stability important optoelectronic properties- gap, lifetime, cell performance - across wide range compositions varying the A-site cation...
Hybrid lead halide perovskites (LHPs) are a class of semiconductor with novel properties that distinctively governed by structural fluctuations. Diffraction experiments sensitive to average, long-range order reveal cubic structure in the device-relevant, high-temperature phase. Local probes find additional short-range lower symmetry may govern structure-function relationships LHPs. However, dimensionality, participating atoms, and dynamics this unresolved, impeding our understanding...