A5077891461- Perovskite Materials and Applications
- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Crystallization and Solubility Studies
- Advanced Fluorescence Microscopy Techniques
- 2D Materials and Applications
- X-ray Diffraction in Crystallography
- Conducting polymers and applications
- Molecular Junctions and Nanostructures
- ATP Synthase and ATPases Research
- Organic Electronics and Photovoltaics
- Organic Light-Emitting Diodes Research
- Catalytic Processes in Materials Science
- Click Chemistry and Applications
- Quantum and electron transport phenomena
- Redox biology and oxidative stress
- Spectroscopy and Quantum Chemical Studies
- Mitochondrial Function and Pathology
- Graphene research and applications
- Solid-state spectroscopy and crystallography
- Gas Sensing Nanomaterials and Sensors
- Advanced Condensed Matter Physics
- Photosynthetic Processes and Mechanisms
- Advanced biosensing and bioanalysis techniques
Purdue University West Lafayette
2017-2020
St. John's University
2017
Extraction of photoexcited charge carriers transported up to 600 nanometers in CH 3 NH PbI could boost solar cell efficiency.
The role of the alkali metal cations in halide perovskite solar cells is not well understood. Using synchrotron-based nano-x-ray fluorescence and complementary measurements, we found that distribution becomes homogenized upon addition cesium iodide, either alone or with rubidium for substoichiometric, stoichiometric, overstoichiometric preparations, where lead varied respect to organic precursors. Halide homogenization coincides long-lived charge carrier decays, spatially homogeneous...
We highlight the recent progress in ultrafast dynamic microscopy that combines optical spectroscopy with approaches, focusing on application transient absorption (TAM) to directly image energy and charge transport solar harvesting conversion systems. discuss principles, instrumentation, resolutions of TAM. The simultaneous spatial, temporal, excited-state-specific TAM unraveled exciton mechanisms were previously obscured conventional measurements for systems such as organic cells, hybrid...
Successful implementation of hot carrier solar cells requires preserving high temperature as carriers migrate through the active layer. Here, we demonstrated that addition alkali cations in hybrid organic-inorganic lead halide perovskites led to substantially elevated temperature, reduced threshold for phonon bottleneck, and enhanced transport. The synergetic effects from Rb, Cs, K result ~900 increase effective at a density around 1018 cm-3 with an excitation 1.45 eV above bandgap. In doped...
For optoelectronic devices based on polycrystalline semiconducting thin films, carrier transport across grain boundaries is an important process in defining efficiency. Here we employ transient absorption microscopy (TAM) to directly measure within and the hybrid organic–inorganic perovskite films for solar cell applications with 50 nm spatial precision 300 fs temporal resolution. By selectively imaging sub-bandgap states, our results show that lateral slowed down by these states at...
Rational design of heterojunctions using nanostructured materials is a useful strategy for achieving efficient interfacial charge separation in photovoltaics. Heterojunctions can be constructed between the organic ligands and inorganic layers two-dimensional perovskites, taking advantage their highly programmable structures. Here, we investigate transfer recombination at interface thiophene-based semiconducting lead halide sublattices time-resolved photoluminescence transient reflection...
We report the synthesis and molecular junction conductance for a series of oligofluorenes to establish clear structure–property relationships this electronically important material. use scanning tunneling microscopy based break-junction method (STM-BJ) measure single-molecule in that vary (a) number fluorene repeat units (n = 1–3), (b) bridge carbon substitution (dihydrogen, dimethyl, dihexyl, didodecyl), (c) linker-group termination (methyl sulfide versus primary amine). Conductance...
Reactive oxygen species (ROS) mediate both intercellular and intraorganellar signaling, ROS propagate oxidative stress between cellular compartments such as mitochondria the cytosol. Each compartment contains its own sources of well antioxidant mechanisms, which contribute to dynamic fluctuations in levels that occur during metabolism, stress. However, coupling redox dynamics has not been studied because lack available sensors simultaneously measure more than one subcellular same cell....
Oxidative stress is a hallmark of several aging and trauma related neurological disorders, but the precise details how altered neuronal activity elicits subcellular redox changes have remained difficult to resolve. Current sensitive dyes fluorescent proteins can quantify spatially distinct in reactive oxygen species levels, multicolor probes are needed accurately analyze compartment-specific dynamics single cells that be masked by population averaging. We previously engineered genetically...
Design rules and application spaces for closed-shell conjugated polymers have been well established in the field of organic electronics, but emerging class open-shell stable radicals has not evaluated such detail. Thus, establishing underlying physical phenomena associated with interactions between both classes molecules is imperative effective utilization these soft materials. Here, we establish that Förster Resonance Energy Transfer (FRET) dominant mechanism by which energy transfer occurs...
Redox status, which can vary over time and across subcellular compartments, is an important indicator of cell activity health. Fluorescent protein sensors are particularly useful for the measurement cellular redox dynamics because they genetically encoded, be targeted to organelles, typically non‐cytotoxic. For example, reduction‐oxidation‐sensitive green fluorescent proteins (roGFPs) that measure detect reactive oxygen species (ROS) [Hanson, G. T. et al. , 2004, J. Biol. Chem. 279,...
Perovskite solar cells have shown remarkable efficiencies beyond 22%, through organic and inorganic cation alloying. However, the role of alkali-metal cations is not well-understood. By using synchrotron-based nano-X-ray fluorescence complementary measurements, we show that when adding RbI and/or CsI halide distribution becomes homogenous. This homogenization translates into long-lived charge carrier decays, spatially homogenous dynamics visualized by ultrafast microscopy, as well improved...
Compositional engineering related to the organic and inorganic cations (A-site) in halide perovskites solar cells has helped improve efficiency long-term durability. However, this compositional complexity can lead phase segregation that weakens optoelectronic performance. Here, we show distribution cation by means of synchrotron-based nanoprobe x-ray fluorescence. We find homogenizes upon addition CsI RbI precursors. The homogenization coincides with long-lived charge carrier decays....