A5052626983- Perovskite Materials and Applications
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Solid-state spectroscopy and crystallography
- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Electronic and Structural Properties of Oxides
- Organic and Molecular Conductors Research
- Photochemistry and Electron Transfer Studies
- Crystal Structures and Properties
- Spectroscopy and Quantum Chemical Studies
- Photonic Crystals and Applications
- Luminescence Properties of Advanced Materials
- Semiconductor materials and devices
- Crystallography and molecular interactions
- ZnO doping and properties
- Advanced Condensed Matter Physics
Colorado State University
2018-2024
University of Wisconsin–Stevens Point
2016-2017
The emission of white light from a single material is atypical and interest for solid-state lighting applications. Broadband has been observed in some layered perovskite derivatives, A2PbBr4 (A = R-NH3+), correlates with static structural distortions corresponding to out-of-plane tilting the lead bromide octahedra. While materials different organic cations can yield distinct tilts, underlying origin octahedral remains poorly understood. Using high energy resolution (e.g., quasi-elastic)...
Manganese sulfide (MnS) thin films were synthesized via atomic layer deposition (ALD) using gaseous manganese bis(ethylcyclopentadienyl) and hydrogen as precursors. At temperatures ≤150 °C phase-pure γ-MnS deposited, while at >150 °C, a mixed phase consisting of both γ- α-MnS resulted. In situ quartz crystal microbalance (QCM) studies validate the self-limiting behavior ALD half-reactions and, combined with quadrupole mass spectrometry (QMS), allow derivation self-consistent reaction...
Copper antimony sulfide (CuSbS2) has been gaining traction as an earth-abundant absorber for thin-film photovoltaics given its near ideal band gap solar energy conversion (∼1.5 eV), large absorption coefficient (>104 cm–1), and elemental abundance. Through careful in situ analysis of the deposition conditions, a low-temperature route to CuSbS2 thin films via atomic layer developed. After short (15 min) postprocess anneal at 225 °C, ALD-grown were crystalline with micron-sized grains,...
Two-dimensional (2D) Ruddlesden–Popper hybrid perovskites are a homologous series of compounds with the formula A′2An–1BnX3n+1 (A′ = bulky organic cation; A small B Pb2+ or Sn2+, X Cl–, Br–, I–; n is an integer) composed inorganic octahedral layers separated by spacer cations. The layer thickness modified stoichiometry A-site cation, but limited methods exist for controlled and discriminating synthesis all compositions. We report general method its principles that yield phase-pure 2D...
Hybrid organic–inorganic semiconductors crystallizing in the perovskite structure present a significant opportunity for realizing defect-tolerant semiconductors. In this work, we examine solid solution, (CH3NH3)1–xCsxSnBr3, and identify thermochemistry dictating intrinsic carrier concentrations how local structural distortions influences electronic behavior. This family of compounds exhibits expected systematic trend decreasing optical gap with cesium to methylammonium A-site mixing ratio,...
The layered Ruddlesden–Popper derivatives of CH3NH3PbI3 have recently emerged as high-performing materials for photovoltaics with improved stability. inclusion organic molecules within the inorganic framework provides additional dynamic degrees freedom that influence optoelectronic properties. rotational dynamics CH3NH3+ dielectric behavior and electronic excited-state in CH3NH3PbI3; however, cation on properties has not yet been determined. We employ quasi-elastic neutron scattering to...
The layered perovskite (MA)2PbI2(SCN)2 (MA = CH3NH3+) is a member of an emerging series compounds derived from hybrid organic–inorganic perovskites. Here, we successfully synthesized (MA)2PbI2–xBrx(SCN)2 (0 ≤ x < 1.6) by using solid-state reaction. Despite smaller bromide substitution for iodine, 1% linear expansion along the axis was observed at ∼ 0.4 due to change orientation SCN– anions. Diffuse reflectance spectra reveal that optical band gap increases substitution, which supported DFT...
A temperature-induced structural phase transition is reported in layered hybrid perovskite (MA) 2 PbI 2− x Br (SCN) (0 ≤ 1.2). The observed temperature decreases with substitution, suggesting a weakening of bonding interaction between the molecular ions.