A5084293829- ZnO doping and properties
- Perovskite Materials and Applications
- Electronic and Structural Properties of Oxides
- Chalcogenide Semiconductor Thin Films
- Conducting polymers and applications
- Copper-based nanomaterials and applications
- Organic Electronics and Photovoltaics
- Silicon and Solar Cell Technologies
- solar cell performance optimization
- Thin-Film Transistor Technologies
- Semiconductor materials and devices
- Quantum Dots Synthesis And Properties
- Ferroelectric and Piezoelectric Materials
- Semiconductor materials and interfaces
- Gas Sensing Nanomaterials and Sensors
- Nanowire Synthesis and Applications
- Photorefractive and Nonlinear Optics
- Organic Light-Emitting Diodes Research
- Transition Metal Oxide Nanomaterials
- Ga2O3 and related materials
- Multiferroics and related materials
- Advanced Thermoelectric Materials and Devices
- Solid-state spectroscopy and crystallography
- Industrial Vision Systems and Defect Detection
- Acoustic Wave Resonator Technologies
National Renewable Energy Laboratory
2016-2025
University of Toledo
2022
Sandia National Laboratories
2022
University of Washington
2022
Fraunhofer Institute for Solar Energy Systems
2017-2020
University of Arizona
2012
Institut National de la Recherche Scientifique
2005-2009
Efficient all-perovskite tandem cells Organic-inorganic perovskite films can boost the output of conventional silicon solar in geometries by utilizing more light at blue end spectrum. Tandem that use only have been less successful because lack a suitable material with low bandgap replace silicon. Tong et al. report mixed tin-lead organic-inorganic containing small fraction guanidinium thiocyanate has bandgap, long charge-carrier lifetime, and efficiencies around 25%. Science , this issue p. 475
Organic–inorganic halide perovskites incorporating two-dimensional (2D) structures have shown promise for enhancing the stability of perovskite solar cells (PSCs). However, bulky spacer cations often limit charge transport. Here, we report on a simple approach based molecular design organic to improve transport properties 2D perovskites, and use phenethylammonium (PEA) as an example. We demonstrate that by fluorine substitution para position in PEA form 4-fluorophenethylammonium (F-PEA),...
Abstract We show enhanced efficiency and stability of a high performance organic solar cell (OPV) when the work‐function hole collecting indium‐tin oxide (ITO) contact, modified with solution‐processed nickel (NiO x ) hole‐transport layer (HTL), is matched to ionization potential donor material in bulk‐heterojunction cell. Addition NiO HTL contact results power conversion ( PCE 6.7%, which 17.3% net increase over 5.7% achieved poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)...
Combining two or more junctions into a tandem solar cell promises to deliver leap in power conversion efficiency that will help sustain continued growth installed photovoltaic (PV) capacity. Although tandems are now on the roadmaps of many PV manufacturers, much work remains before they ready for mass deployment. Accelerating their development requires advances fronts. In this article, we outline fundamentals and status PV, considering multiple technology pairings architectures. We then...
We have utilized a commercially available metal–organic precursor to develop new, low-temperature, solution-processed molybdenum oxide (MoOx) hole-collection layer (HCL) for organic photovoltaic (OPV) devices that is compatible with high-throughput roll-to-roll manufacturing. Thermogravimetric analysis indicates complete decomposition of the by 115 °C in air. Acetonitrile solutions spin-cast N2 atmosphere and annealed air yield continuous thin films MoOx. Ultraviolet, inverse, X-ray...
We report the charge carrier recombination rate and spin coherence lifetimes in single crystals of two-dimensional (2D) Ruddlesden–Popper perovskites PEA2PbI4·(MAPbI3)n−1 (PEA, phenethylammonium; MA, methylammonium; n = 1, 2, 3, 4). Layer thickness-dependent rates are observed, with fastest for 1 because large exciton binding energy, slowest observed 2. Room-temperature times also show a nonmonotonic layer thickness dependence an increasing lifetime from to 4, followed by decrease 4 ∞. The...
In this work, the impact of cation disorder on electrical properties biaxially textured Co 2 ZnO 4 and NiO thin films grown by pulsed laser deposition are investigated using a combination experiment theory. Resonant elastic X‐ray diffraction along with conductivity measurements both before after post‐deposition annealing show that exhibit opposite changes disorder, which can be traced back to their different ground‐state atomic structures, being normal inverse spinel, respectively....
Spectroscopic ellipsometry analysis of optical transitions and constants in hybrid organic–inorganic perovskite alloys.
Interstitial zinc defects in solution-processed ZnO can be mitigated by using a diethylzinc precursor instead of acetate, or modifying the surface with phosphonic acid, resulting improved organic solar cell stability.
With the ultimate goal of finding new polymorphs through targeted synthesis conditions and techniques, we outline a computational framework to select optimal substrates for epitaxial growth using first principle calculations formation energies, elastic strain energy, topological information. To demonstrate approach, study stabilization metastable VO2 compounds which provides rich chemical structural polymorph space. We find that common statistics, lattice matching, energy above hull...
Holes can be readily doped into small-gap semiconductors such as Si or GaAs, but corresponding $p$-type doping in wide-gap insulators, while maintaining transparency, has proven difficult. Here, by utilizing design principles distilled from theory with systematic measurements the prototype ${A}_{2}B$O${}_{4}$ spinel Co${}_{2}$ZnO${}_{4}$, we formulate and test practical rules for effective hole doping. Using these, demonstrate a 20-fold increase density Co${}_{2}$ZnO${}_{4}$ due to extrinsic...
We explore the effects of cation off-stoichiometry on structural, electrical, optical, and electronic properties Co${}_{2}$ZnO${}_{4}$ normal spinel Co${}_{2}$NiO${}_{4}$ inverse using theoretic experimental (combinatorial conventional) techniques, both at thermodynamic equilibrium in metastable regime. Theory predicts that nonequilibrium substitution divalent Zn nominally trivalent octahedral sites increases net hole density Co${}_{2}$ZnO${}_{4}$. Experiment confirms high conductivity work...
Solar thermoelectric generators (STEGs) have the potential to convert solar energy at greater than 15% efficiency. This project investigates system design, necessary and optical technologies, economic feasibility of STEG approach. A is a solid-state heat engine that converts sunlight directly into DC electricity through effect. STEGs consist three subsystems: absorber, generator (TEG), management (insulation, exchanger, vacuum enclosure, etc.). will integrate several state-of-the-art...
Abstract To accelerate the design and discovery of novel functional materials, here, p‐type transparent conducting oxides, an inverse approach is formulated, integrating three steps: i) articulating target properties selecting initial pool candidates based on “design principles”, ii) screening this by calculating “selection metrics” for each member, iii) laboratory realization more‐detailed theoretical validation remaining “best‐of‐class” materials. Following a principle that suggests using...
A systematic study of the role insulator layer on rectification performance in metal–insulator–metal structures is reported. Four different MIM systems with Nb/Pt metal pairs and Nb2O5, TiO2, Al2O3, MgO as candidates are investigated based an empirical hypothesis. As per hypothesis experimental verification, several prospective such Sm/ZrO2/Pt Hf/TiO2/Pt identified a materials-space constructed.
We investigate the prototypical hybrid interface formed between PTCDA and conductive n-doped ZnO films by means of complementary optical electronic spectroscopic techniques. demonstrate that shallow donors in vicinity surface cause an integer charge transfer to PTCDA, which is clearly restricted first monolayer. By DFT calculations, we show experimental signatures anionic species can be understood terms strong hybridization with localized states (the donors) substrate back-donation,...
The interfacial electronic structure between oxide thin films and organic semiconductors remains a key parameter for optimum functionality performance of next‐generation organic/hybrid electronics. By tailoring defect concentrations in transparent conductive ZnO films, we demonstrate the importance controlling electron transfer barrier at interface with acceptor molecules such as C 60 . A combination spectroscopy, density functional theory computations, device characterization is used to...
Although transition-metal oxides usually lack the combination of suitable band gaps and carrier transport properties desired for solar energy applications, such semiconducting can be realized in metastable MnO-ZnO alloys.
We report third-order nonlinear coefficient values and decay time kinetics <italic>vs.</italic> halide composition (CH<sub>3</sub>NH<sub>3</sub>PbBr<sub>3</sub> CH<sub>3</sub>NH<sub>3</sub>PbBr<sub>2</sub>I), temperature, excitation wavelength.
Theoretically predicted metastable phases are realized in thin-film synthesis of Mn 1− x Zn O and Sn Ca S alloys.
Three-terminal tandem solar cell with conductive adhesive interconnect and back-contacted bottom delivers 27.3% efficiency.
Decomposition/oxidation correlated to nanoscale c-AFM helps separate selectivity and conductivity.
The electronic structure of the hybrid interface between ZnO and prototypical organic semiconductor PTCDI is investigated via a combination ultraviolet X-ray photoelectron spectroscopy (UPS/XPS) density functional theory (DFT) calculations. interfacial interactions lead to large dipole due substantial charge transfer from 3,4,9,10-perylenetetracarboxylicdiimide (PTCDI), which can be properly described only when accounting for surface defects that confer its n-type properties.
Self-doping of cations on the tetrahedral and octahedral sites in spinel oxides creates “anti-site” defects, which results functional optical, electronic, magnetic, other materials properties. Previously, we divded III–II family into four doping types (DTs) based first-principle calculations order to understand their electrical behavior. Here, present experimental evidence two prototype spinels for each major type (DT1 DT4) that test first principles calculations. For DT-1 Ga2ZnO4 spinel,...