A5045812966- Perovskite Materials and Applications
- Quantum Dots Synthesis And Properties
- Chalcogenide Semiconductor Thin Films
- Solid-state spectroscopy and crystallography
- Conducting polymers and applications
- Layered Double Hydroxides Synthesis and Applications
- Advanced Photocatalysis Techniques
- Semiconductor Quantum Structures and Devices
- Advanced Battery Technologies Research
- Surface Roughness and Optical Measurements
- Reservoir Engineering and Simulation Methods
- Ion-surface interactions and analysis
- Laser-induced spectroscopy and plasma
- Magnetic and transport properties of perovskites and related materials
- Oil and Gas Production Techniques
- 2D Materials and Applications
Georgia Institute of Technology
2019-2025
Helmholtz-Zentrum Berlin für Materialien und Energie
2024
Massachusetts Institute of Technology
2021-2024
Lawrence Berkeley National Laboratory
2023
Wesleyan University
2021
Argonne National Laboratory
2021
Sinopec (China)
2013
Optica
2004
Abstract Grain boundaries (GBs) play an important role in most polycrystalline solar cells. In perovskite cells, the research community is just starting to understand their effects on performance and long‐term durability. this essay, three questions are explored: Do GBs affect: 1) recombination thus open‐circuit voltage? Not dramatically, if at all; 2) current–voltage hysteresis? Most studies show that hysteresis dominated by defects GBs; 3) durability? Yes, definitely help increase rate of...
Halide perovskites are a strong candidate for the next generation of photovoltaics. Chemical doping halide is an established strategy to prepare highest efficiency and most stable perovskite-based solar cells. In this study, we unveil mechanism using series alkaline earth metals. We find that low levels enable incorporation dopant within perovskite lattice, whereas high concentrations induce surface segregation. The threshold from regime correlates size element. show results in more n-type...
The certified power conversion efficiency of state-of-the-art organic–inorganic hybrid perovskite solar cells has surpassed 25%, showing promising potential for commercialization. Compared with volatile methylammonium-based perovskites, formamidinium- and cesium-based halide perovskites have attracted attention due to their resistance thermal degradation. However, the photoactive phases these materials suffer from limited phase stability at room temperature are prone spontaneous...
The impact of the bulky-cation-modified interfaces on halide perovskite solar cell stability is underexplored. In this work, thermal instability bulky-cation interface layers used in state-of-the-art cells demonstrated. X-ray photoelectron spectroscopy and synchrotron-based grazing-incidence scattering measurements reveal significant changes chemical composition structure at surface these films that occur under stress. charge-carrier dynamics device operation, as shown transient...
Abstract Halide perovskite semiconductors have risen to prominence in photovoltaics and light‐emitting diodes (LEDs), but traditional oxide perovskites, which overcome the stability limitations of their halide counterparts, also recently witnessed a rise potential as solar absorbers. One many important factors underpinning these developments is an understanding role dimensionality on optoelectronic properties and, consequently, performance materials LEDs. This review article examines...
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...
Mixed-cation metal halide perovskites have shown remarkable progress in photovoltaic applications with high power conversion efficiencies. However, to achieve large-scale deployment of this technology, efficiencies must be complemented by long-term durability. The latter is limited external factors, such as exposure humidity and air, which lead the rapid degradation perovskite materials devices. In work, we study mechanisms causing Cs formamidinium (FA)-based phase transformations...
Abstract Perovskite solar cells (PSCs) have attracted much attention as efficiencies gone beyond 24%. To achieve these impressive numbers, the PSC scientific community is working to improve perovskite optoelectronic properties. Imaging and mapping characterization techniques been widely used understand fundamental properties that allow lead halide perovskites high performance. In this review, are evaluated, from simple tools, such electron microscopy, more complex systems include atomic...
Interfacial passivation with bulky organic cations such as phenetylammonium iodide has enabled high performance for metal halide perovskite optoelectronic devices. However, the homogeneity of these interfaces and their formation dynamics are poorly understood. We study how Ruddlesden–Popper 2D phases form at a 3D interface when precursors introduced via solution or vapor. When using vapor deposition, we observe uniform coverage capping layer predominantly n = 2 phase. In contrast, presence...
Lead halide perovskites (LHPs) are promising semiconductors for optoelectronic applications. In LHP solar cells, the focus thus far has been mainly on compositional optimization of MHP layer, without much understanding effects mixing structure and texture. This is a serious gap in our knowledge because research shown that texture underlies mechanisms charge carrier ionic transport. Therefore, it essential to understand drive changes LHPs. work examines effect moisture composition LHPs their...
The fundamental structure–property relationships in the Cs y FA 1− Pb(Br x I ) 3 compositional space are reported.
Abstract The intriguing functionalities of emerging quasi‐2D metal halide perovskites (MHPs) have led to further exploration this material class for sustainable and scalable optoelectronic applications. However, the chemical complexities in precursors—primarily determined by 2D:3D compositional ratio—result uncontrolled phase heterogeneities these materials, which compromises performances. Yet, phenomenon remains poorly understood due massive space. To systematically explore fundamental...
Abstract Compositional heterogeneity in wide-bandgap (1.8 − 2.1 eV) mixed-halide perovskites is a key bottleneck the processing of high-quality solution-processed thin films and prevents their application efficient multijunction solar cells. Notably, mixed-cation (formamidinium-methylammonium) perovskite are prone to form micrometer-scale wrinkles which can interfere with smooth surfaces ideal for devices. Here, we study formation dynamics wrinkled its impact on local composition...
Preferred crystallographic orientation in polycrystalline films is desirable for efficient charge carrier transport metal halide perovskites and semiconductors. However, the mechanisms that determine preferred of are still not well understood. In this work, we investigate lead bromide perovskites. We show solvent precursor solution organic A-site cation strongly affect deposited perovskite thin films. Specifically, solvent, dimethylsulfoxide, influences early stages crystallization induces...
Mixed-cation and mixed-halide lead halide perovskites show great potential for their application in photovoltaics. Many of the high-performance compositions are made cesium, formamidinium, lead, iodine, bromine. However, incorporating bromine iodine-rich its effects on thermal stability perovskite structure has not been thoroughly studied. In this work, we study how replacing iodine with state-of-the-art Cs0.17FA0.83PbI3 composition leads to different dynamics phase transformations as a...
Quasi-2D perovskites have been pivotal in recent efforts to stabilize perovskite solar cells. Despite the stability boost provided when these materials are introduced cells, little is known about intrinsic light and environmental of quasi-2D perovskites. In this study, we characterize photostability exfoliated single crystals air using photoluminescence, infrared, X-ray fluorescence, energy-dispersive spectroscopy. Photoexcitation leads severe material loss with oxygen as a prerequisite for...
Alkali addition in organic–inorganic perovskite has become the standard recipe for achieving solar cells with efficiencies exceeding 20%, but mechanism is not well understood. We use non-contact carrier lifetime measurements, mobility and synchrotron-based x-ray characterization techniques to show that there a unique benefit adding hybrid samples Rb Cs simultaneously. When either or added, charge increases alkali concentration. Charge benefits from incorporation as well, optimized only...
The intriguing functionalities of emerging quasi-two-dimensional (2D) metal halide perovskites (MHPs) have led to further exploration this material class for sustainable and scalable optoelectronic applications. However, the chemical complexities in precursors – primarily determined by 2D:3D compositional ratio result uncontrolled phase heterogeneities these materials, which compromises performances. Yet, phenomenon remains poorly understood due massive quasi-2D space. To systematically...
Mixed-cation mixed-halide lead perovskites have been shown to be excellent candidates for solar energy conversion. However, understanding the structural phases of these mixed-ion across a wide range operating temperatures, including very low temperatures space applications, is crucial. In this study, we investigated structure formamidinium-based Cs
Atomic layer deposition (ALD) allows for fine control over the thickness, stoichiometry, and structural defects of materials. ALD provides a suitable route to deposit lead halides, which can further be converted perovskites photovoltaics, photoemission, photodetection, among other applications. Deposition halides by has already begun explored; however, precursors used in published processes are highly hazardous, require expensive fabrication processes, or contain impurities that jeopardize...