Research Highlights

Explore these overviews of our recent research projects.

2022 Research Highlights

Kinetically Controlled Structural Transitions in Layered Halide-Based Perovskites: An Approach to Modulate Spin Splitting »

Ultrafast (“flash”) differential scanning calorimetry shows a relaxation time that is on the minute timescale at the transition temperature (enabling kinetic control).

Aug. 24, 2022

Influence of Annealing and Composition on Crystal Structure of Mixed-Halide, Ruddlesden-Popper Perovskites »

Hybrid organic-inorganic semiconductors, such as hybrid perovskites, are crystalline materials with unique properties derived from the organic or inorganic components.

March 19, 2022

The Structural Origin of Chiroptical Properties in Perovskite Nanocrystals with Chiral Organic Ligands »

Colloidal metal halide perovskite nanocrystals provide an outstanding platform for exploring chirality-mediated electro-optical phenomena.

March 16, 2022

2021 Research Highlights

Metastable Dion-Jacobson 2D Structure Enables Efficient and Stable Perovskite Solar Cells »

A general design strategy was reported to maximize hole transport across the bulky cationic organic layers in 2D perovskites by using a metastable Dion-Jacobson 2D structure.

Nov. 25, 2021

Stabilizing Perovskite-Substrate Interfaces for High-Performance Perovskite Modules »

Dimethyl sulfoxide was found trapped during film formation and led to voids at perovskite-substrate interfaces that accelerated the film degradation under illumination.

Aug. 19, 2021

Charge Transfer States and Carrier Generation in 1D Organo-Lead Iodide Semiconductors »

Many different structural and spectroscopic probes are utilized to connect the structure and energy landscape of the organic/inorganic interface to the dynamics of photoinduced charges in novel 1D metal halide semiconductors.

June 15, 2021

Low-Energy Room-Temperature Optical Switching in Mixed-Dimensionality Nanoscale Perovskite Heterojunctions »

For some applications, metal halide perovskite materials have problematically high-ion migration properties. However, that same property can also be exploited as a beneficial feature for certain technologies.

April 28, 2021

Direct Detection of Circularly Polarized Light Using Chiral Copper Chloride—Carbon Nanotube Heterostructures »

The chiral heterostructure shows high sensitivity for photon detection and one of the best abilities demonstrated to date to discriminate between right- and left-handed circularly polarized photons.

April 6, 2021

Chiral-Induced Spin Selectivity Enabling a Room-Temperature Spin Light-Emitting Diode »

Chiral-induced spin selectivity was used to produce spin-polarized carriers and demonstrate a spin-LED that operates at room temperature without magnetic fields or ferromagnetic contacts.

March 12, 2021

Surface Lattice Engineering through Three-Dimensional Lead Iodide Perovskitoid for High-Performance Perovskite Solar Cells »

Three-dimensional perovskitoid Pb2I6 surface layer modification by a simple surface treatment with Me-PDAI2 on top of a 3D perovskite thin film, led to smoother surface texture, longer charge-carrier lifetime, higher charge-carrier mobility, and reduced surface-defect density.

March 11, 2021

Mechanism of Additive-Assisted, Room-Temperature Processing of Metal Halide Perovskite Thin Films »

In-situ synchrotron grazing incidence wide angle X-ray scattering and photoluminescence was used to elucidate the mechanism of improved film formation and crystallization kinetics.

March 9, 2021

Reconfiguring the Band-Edge States of Lead-Halide Perovskite Semiconductors »

A π-conjugation-induced extension of electronic states of A-site cations was reported that impacts perovskite frontier orbitals.

Feb. 25, 2021

2020 Research Highlights

Organic-to-Inorganic Structural Chirality Transfer and Impact on Rashba-Dresselhaus Spin-Splitting in 2D Perovskites »

The ability to break structural symmetry using chirality transfer from one structural unit to another provides a synthetic design paradigm for emergent properties, including spin-polarization for hybrid perovskite spintronics and related applications.

Sept. 17, 2020

Highly Distorted Chiral Tin-Iodide with Spin Polarized Transport »

Oriented organic molecules within the 2D hybrid perovskite system can induce new functionality.

June 30, 2020

Resolving Spatial and Energetic Distributions of Trap States in Metal Halide Perovskite Solar Cells »

Polycrystalline perovskite solar cell efficiencies can be improved by reducing both the surface and bulk trap densities.

March 20, 2020

Charge Carrier Transport through Ferroelastic Twin Boundaries in Halide Perovskite »

The twin boundaries formation does not decrease the device efficiency but can make perovskite electronic devices more flexible.

May 5, 2020

Ultrafast Reaction Mechanism in Perovskite Bases Photocatalytic C-C Coupling »

Photoexcited perovskite nanocrystals (NCs) can initiate photo-redox reactions by reducing and oxidization various substrates on ultrafast timescale.

Jan. 21, 2020

Circular Photogalvanic Spectroscopy of the Giant Rashba Splitting in 2D Hybrid Organic-Inorganic Perovskites »

Measurements of the Rashba splitting is an essential component of controlling Rashba splitting.

Jan. 16, 2020

Past Research Highlights

Intense Broadband Emission in Layered Perovskites »

Broadband emission in Ruddlesden-Popper lead iodide perovskites can be induced through cation impurity atom doping and/or alloying.

Dec. 27, 2019

Negative Surface Energy for Stabilization »

The quantum confinement properties enabled by colloidal nanocrystal synthesis not only offer the opportunity to tune the light emission wavelength but can also be used to understand basic properties fundamental properties.

Dec. 18, 2019

Efficient Blue Perovskite Light-Emitting Diodes via Photoluminescence Enhancement »

Matching electron and hole current achieves record external quantum efficiency of 11% and brightness of 9040 cd/m2 in the YCl3 incorporated blue perovskite light-emitting diodes.

Dec. 10, 2019 

Spin-Dependent Charge Transport through 2D Chiral Hybrid Perovskite Layers »

Here we demonstrate how to integrate an oriented chiral organic sublattice into an inorganic framework, creating a semiconducting chiral system that can transport electrons with the desired spin control.

Dec. 6, 2019

Separating Electron and Hole Mobility in 3D Metal-Halide Perovskite »

Here we combine two methods—transient reflectance spectroscopy and terahertz spectroscopy—to detect both the electron and hole mobilities.

Nov. 21, 2019

Enhancing Electron Diffusion Length in Narrow Bandgap Perovskites for Efficient All-Perovskite Tandem Solar Cells »

This work provides a promising method to enhance the optoelectronic properties of narrow-bandgap perovskites, which unlock the potential of high-efficiency, low-cost, and solution-processable perovskite-perovskite tandem solar cells.

Oct. 3, 2019

Lead Halide Perovskites for Photocatalytic Organic Synthesis »

Low-cost, easy-to-process, highly efficient, air-tolerant, and bandedge-tunable perovskites may bring new breakthroughs in organic chemistry photocatalysis.

June 28, 2019

Perovskite Heterojunction Quantum Dot Films with Charge-Separating Interface »

Metal halide perovskite semiconductors, with chemical composition ABX3, possess outstanding characteristics for optoelectronic applications, including but not limited to photovoltaics.

June 28, 2019

Rapid Charge-Transfer Cascade through SWCNT composites Enabling Low-Voltage Losses for Perovskite Solar Cells »

By comparing the charge transfer interface between single-walled carbon nanotubes and perovskite layers in multiple different configurations, we find that the charge transport characteristics of the secondary charge-collecting layer is pivotal to achieving low interfacial recombination and the resulting high VOC.

June 20, 2019

Tunable Self-Assembling Organic-Inorganic Quantum Wells »

Films deposited by resonant-infrared matrix-assisted pulsed laser evaporation enable transient absorption spectroscopy measurements on oligothiophene-based lead halide perovskites, providing a critical window into excited state dynamics and validating hybrid density functional theory predictions of quantum well alignment between the various inorganic/organic moieties.

May 16, 2019

Exciton Fine Structure in CsPbBr3 Nanocrystals »

No other known semiconductor system has the lowest energy state being bright implying that these systems are ideal for applications that require fast and bright radiative emission.

May 15, 2019

Conductivity Tuning via Doping with Electron Donating and Withdrawing Molecules in Perovskite CsPbl3 Nanocrystal Films »

Enhanced conductivity for p-type nanocrystal (NC) arrays enables significant improvements to field-effect transistors and phototransistors, which should, in turn, lead to performance improvements in light-detecting applications and solar cells.

May 10, 2019 

Carrier Lifetimes of >1 ms in Sn-Pb Perovskites Enable Efficient All-Perovskite Tandem Solar Cells »

The addition of guanidinium thiocyanate results in marked improvements in the structural and optoelectronic properties of Sn-Pb mixed, low-band gap (~1.25- eV) perovskite films.

May 3, 2019

Enhanced Charge Transport in 2D Perovskites via Fluorination of Organic Cation »

Through fluorine substitution on the para position in phenethylammonium (PEA) to form 4-fluorophenethylammonium (F-PEA), the average phenyl ring centroid−centroid distances in the organic layer become shorter with better aligned stacking of perovskite sheets.

March 18, 2019

Sensitizing Singlet Fission with Perovskite Nanocrystals »

Singlet fission is a process that occurs in organic molecules and can enhance solar energy conversion.

March 1, 2019

Lead-Halide Perovskites for Photocatalytic C-C bond Formation »

The as-prepared perovskite nanocrystals are effective in photocatalysis with a turnover number of over 52,000 for a-alkylation, three orders of magnitude higher than precious Ir or Ru catalysts.

Jan. 2, 2019

Mechanism of Enhanced Broadband Emission »

Lattice distortion promotes a self-trapped exciton that emits broadband white light with a very high efficiency.

Nov. 7, 2018

Spin-Coherence Time as a Function of Layer Thickness »

In addition to larger structural distortion in 2D layered systems, there is a larger phonon coupling to carriers. These two effects can counterbalance each other to produce the longest live spin-coherence lifetime in a layered system where the layers contain 4 PbI62- octahedra.

Aug. 28, 2018