A5089172567- Perovskite Materials and Applications
- 2D Materials and Applications
- Quantum Dots Synthesis And Properties
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Conducting polymers and applications
- Solid-state spectroscopy and crystallography
- Synthesis and Properties of Aromatic Compounds
- Photorefractive and Nonlinear Optics
- Electronic and Structural Properties of Oxides
- Semiconductor Quantum Structures and Devices
- Inorganic Chemistry and Materials
- Crystallography and molecular interactions
- Advanced Photocatalysis Techniques
- Chalcogenide Semiconductor Thin Films
- Organic and Molecular Conductors Research
- Photonic and Optical Devices
- Quantum and electron transport phenomena
- Organic Light-Emitting Diodes Research
- Organic Chemistry Cycloaddition Reactions
- Photochromic and Fluorescence Chemistry
- Physics of Superconductivity and Magnetism
- Machine Learning in Materials Science
- Luminescence and Fluorescent Materials
- Advanced Condensed Matter Physics
National Renewable Energy Laboratory
2018-2025
University of Wisconsin–Madison
2017-2024
Wuhan National Laboratory for Optoelectronics
2020
Huazhong University of Science and Technology
2020
Southern Illinois University Carbondale
2017-2018
HaitiChildren
2018
Abstract Lead halide perovskite quantum dots (QDs) possess color‐tunable and narrow‐band emissions are very promising for lighting display applications, but they suffer from lead toxicity instability. Although lead‐free Bi‐based Sn‐based QDs (CsSnX 3 , Cs 2 SnX 6 (CH NH ) Bi X 9 reported, all show low photoluminescence yield (PLQY) poor stability. Here, the synthesis of Br with high PLQY excellent stability is reported. Via a green facile process using ethanol as antisolvent, as‐synthesized...
High-quality metal halide perovskite single crystals have low defect densities and excellent photophysical properties, yet thin films are the most sought after material geometry for optoelectronic devices. Perovskite single-crystal (SCTFs) would be highly desirable high-performance devices, but their growth remains challenging, particularly inorganic perovskites. Herein, we report facile vapor-phase epitaxial of cesium lead bromide (CsPbBr3) continuous SCTFs with controllable micrometer...
The development of highly stable and efficient wide-bandgap (WBG) perovskite solar cells (PSCs) based on bromine-iodine (Br-I) mixed-halide (with Br greater than 20%) is critical to create tandem cells. However, issues with Br-I phase segregation under cell operational conditions (such as light heat) limit the device voltage stability. This challenge often exacerbated by ready defect formation associated rapid crystallization Br-rich chemistry antisolvent processes. We combined a gentle...
All-inorganic cesium lead iodide (CsPbI3) perovskite has improved thermal stability over the organic–inorganic hybrid perovskites and a suitable bandgap for optoelectronic photovoltaic applications, but it is thermodynamically unstable at room temperature multiple structural polymorphs. Here, we show that use of long-chain ammonium additives during thin film deposition as surface capping ligands results in stabilization metastable bulk CsPbI3 phases without alloying mixed cations or anions...
The stability and formation of a perovskite structure is dictated by the Goldschmidt tolerance factor as general geometric guideline. has limited choice cations (A) in 3D lead iodide perovskites (APbI3), an intriguing class semiconductors for high-performance photovoltaics optoelectronics. Here, we show requirement relaxed 2D Ruddlesden–Popper (RP) perovskites, enabling incorporation variety larger beyond methylammonium (MA), formamidinium, cesium ions cages first time. This unequivocally...
Abstract Designing two-dimensional halide perovskites for high-performance optoelectronic applications requires deep understanding of the structure-property relationship that governs their excitonic behaviors. However, a design framework considers both intra and interlayer structures modified by A-site spacer cations, respectively, has not been developed. Here, we use pressure to synergistically tune uncover structural modulations result in improved performance. Under applied pressure, (BA)...
We report a nontraditional synthesis of cyclopentafused-polycyclic aromatic hydrocarbon embedded ladder polymers using palladium catalyzed cyclopentannulation polymerization followed by cyclodehydrogenation reaction. Donor-acceptor type containing cyclopenta[hi]aceanthrylene acceptor groups can be synthesized copolymerization between 9,10-dibromoanthracene and variety bis(arylethynyl)arenes to give with molecular weights (Mn) 9-22 kDa. The were composed benzene, thiophene, or...
Fabrication of heterostructures using two-dimensional (2D) materials with different bandgaps creates opportunities for exploring new properties and device applications. Ruddlesden-Popper (RP) layered halide perovskites have recently emerged as a class solution-processable 2D that demonstrate exotic optoelectronic properties. However, not been achieved. Here, we report simple solution growth method making vertically stacked double complex multilayer lead iodide [(PEA)2(MA) n-1Pb nI3 n+1, PEA...
Abstract A remarkable PL enhancement by 12 fold is achieved using pressure to modulate the structure of a recently developed 2D perovskite (HA) 2 (GA)Pb I 7 (HA= n ‐hexylammonium, GA=guanidinium). This features previously unattainable, extremely large cage. In situ structural, spectroscopic, and theoretical analyses reveal that lattice compression under mild within 1.6 GPa considerably suppresses carrier trapping, leading significantly enhanced emission. Further pressurization induces...
Abstract Atomic‐resolution imaging of halide perovskites (HPs) using transmission electron microscopy (TEM) is challenging because the sensitivity their structures to beam. In this article, recent achievements in area are reviewed, covering both all‐inorganic and organic–inorganic hybrid HPs, with an emphasis on specific conditions that have proven be effective avoiding beam‐induced structural damage. The discussion focusses total dose HPs can bear before being damaged effects different...
Two-dimensional-on-three-dimensional (2D/3D) halide perovskite heterostructures have been extensively utilized in optoelectronic devices. However, the labile nature of perovskites makes it difficult to form such with well-defined compositions, orientations, and interfaces, which inhibits understanding carrier transfer properties across these heterostructures. Here, we report solution growth both horizontally vertically aligned 2D (PEA)2PbBr4 (PEA = phenylethylammonium) microplates onto 3D...
Abstract Recent activity in the area of chiroptical phenomena has been focused on connection between structural asymmetry, electron spin configuration and light/matter interactions chiral semiconductors. In these systems, spin‐splitting emerge due to inversion symmetry breaking presence extended electronic states, yet is lacking. Here, we develop an analytical effective mass model excitons, parameterized by density functional theory. The accounts for parity mixing band edge Bloch functions...
Two-dimensional (2D) atomic layered semiconductor (e.g., transition metal dichalcogenides, TMDCs) heterostructures display diverse novel interfacial carrier properties and have potential applications in constructing next generation highly compact electronics optoelectronics devices. However, the optoelectronic performance of this kind has difficulty reaching expectations practical applications, due to intrinsic weak optical absorption atomic-thick component layers. Here, combining...
Current understanding of the effects various A-site cations on photophysical properties halide perovskites (APbI3) is limited by compositional tunability. Here we report synthesis and characterization colloidal nanoplates a series 2D Ruddlesden–Popper (RP) (HA)2(A)Pb2I7 (HA = n-hexylammonium) with seven small large to reveal size such A cations. Absorbance photoluminescence (PL) measurements show clear parabolic trend optical band gap versus cation size, methylammonium formamidinium near...
Heterostructures of three-dimensional (3D) halide perovskites are unstable because facile anion interdiffusion at interfaces. Two-dimensional (2D) Ruddlesden–Popper (RPPs) show suppressed and anisotropic ion diffusion that could enable stable RPP heterostructures, yet the direct general growth lateral heterostructures remains challenging. Here, we miscibility in RPPs decreases with perovskite layer thickness (n), enabling formation sharp from n = 1 2 RP lead iodide microplates via exchange...
The development of metal halide perovskite/perovskite heterostructures is hindered by rapid interfacial diffusion leading to mixed alloys rather than sharp interfaces. To circumvent this outcome, we developed an ion-blocking layer consisting single-layer graphene (SLG) deposited between the perovskite layers and demonstrated that it effectively blocks anion in a CsPbBr3/SLG/CsPbI3 heterostructure. Spatially resolved elemental analysis spectroscopic measurements demonstrate halides do not...
We report novel two-dimensional lead halide perovskite structures templated by a unique conjugated aromatic dication, N,N-dimethylphenylene-p-diammonium (DPDA). The asymmetrically substituted primary and tertiary ammoniums in DPDA facilitate the formation of network (2DN) incorporating dication between PbX42– (X = Br, I) layers. These 2DN (DPDA)PbI4 (DPDA)PbBr4 were characterized single-crystal X-ray diffraction, showing uniquely low distortions Pb–X–Pb bond angle for 2D perovskites. Pb–I–Pb...
Abstract A remarkable PL enhancement by 12 fold is achieved using pressure to modulate the structure of a recently developed 2D perovskite (HA) 2 (GA)Pb I 7 (HA= n ‐hexylammonium, GA=guanidinium). This features previously unattainable, extremely large cage. In situ structural, spectroscopic, and theoretical analyses reveal that lattice compression under mild within 1.6 GPa considerably suppresses carrier trapping, leading significantly enhanced emission. Further pressurization induces...
The presence of unreacted lead iodide in organic–inorganic halide perovskite solar cells is widely correlated with an increase power conversion efficiency. We investigate the mechanism for this by identifying role surfaces and interfaces present between methylammonium films excess iodide. show how type I II band alignments arising under different conditions result either passivation surface defects or hole injection. Through first-principles simulations solid–solid interfaces, we find that...
Compared with their 3D counterparts, 2D hybrid organic-inorganic halide perovskites (HOIPs) exhibit enhanced chemical stabilities and superior optoelectronic properties, which can be further tuned by the application of external pressure. Here, we report first high-pressure study on CMA2PbI4 (CMA = cylcohexanemethylammonium), a HOIP soft organic spacer cation containing flexible cyclohexyl ring, using UV-visible absorption, photoluminescence (PL) vibrational spectroscopy, synchrotron X-ray...