Edward H Sargent

University of Toronto | U of T · The Edward S. Rogers Sr. Department of Electrical and Computer Engineering

The discovery of passivating agents for perovskite photovoltaics can be an arduous and time-consuming process. Now, a machine-learning model is reported that accelerates the selection of bifunctional pseudo-halide passivators. The identified pseudo-halide passivators were experimentally shown to enhance the performance of perovskite solar cells.

Performing CO2 reduction in acidic conditions enables high single-pass CO2 conversion efficiency. However, a faster kinetics of the hydrogen evolution reaction compared to CO2 reduction limits the selectivity toward multicarbon products. Prior studies have shown that adsorbed hydroxide on the Cu surface promotes CO2 reduction in neutral and alkalin...

Operating stability has become a priority issue for all-perovskite tandem solar cells. Inorganic CsPbI3−xBrx perovskites, which have good photostability against halide segregation, are promising alternatives for all-perovskite tandem solar cells. However, the interface between organic transport layers and inorganic perovskite suffers from a large e...

CO 2 electrolysis is a promising technology that can utilize intermittent renewable electricity to mitigate CO 2 emissions. In conventional electrolyzers, most of the reactant CO 2 is lost to parasitic side reactions, limiting the electrochemical conversion of CO 2 into valuable products. Here, we present a microchanneled solid electrolyte that int...

While total internal reflection (TIR) lays the foundation for many important applications, foremost fibre optics that revolutionised information technologies, it is undesirable in some other applications such as light-emitting diodes (LEDs), which are a backbone for energy-efficient light sources. In the case of LEDs, TIR prevents photons from esca...

Near-infrared light-emitting diodes based on solution-processed semiconductors, such as organics, halide perovskites and colloidal quantum dots, have emerged as a viable technological platform for biomedical applications, night vision, surveillance and optical communications. The recently gained increased understanding of the relationship between m...

Electrochemical reduction of CO 2 (CO 2 R) to formic acid upgrades waste CO 2 ; however, up to now, chemical and structural changes to the electrocatalyst have often led to the deterioration of performance over time. Here, we find that alloying p-block elements with differing electronegativities modulates the redox potential of active sites and sta...

Perovskite quantum dots (QDs) are of interest for solution‐processed lasers; however, their short Auger lifetime has limited lasing operation principally to the femtosecond temporal regime the photoexcitation levels to achieve optical gain threshold are up to two orders of magnitude higher in the nanosecond regime than in the femtosecond. Here the...

The open-circuit voltage (Voc) of perovskite solar cells is limited by non-radiative recombination at perovskite/carrier transport layer (CTL) interfaces. 2D perovskite post-treatments offer a means to passivate the top interface; whereas, accessing and passivating the buried interface underneath the perovskite film requires new material synthesis...

Advances in colloidal quantum dots The confinement found in colloidal semiconductor quantum dots enables the design of materials with tunable properties. García de Arquer et al . review the recent advances in methods for synthesis and surface functionalization of quantum dots that enable fine tuning of their optical, chemical, and electrical proper...

Solution‐processed organic electro‐optic (EO) chromophores are well suited for integration in optical modulators on silicon photonics chips. They contain highly conjugated molecules with polar functional groups offering large dipoles and a large nonlinear optical response. However, these molecules form centrosymmetric aggregates that hinder poling...

Membrane electrode assembly (MEA) electrolyzers can perform stable, high-rate carbon dioxide (CO2) electroreduction for renewable fuels and chemicals, thereby realizing effective carbon utilization to mitigate anthropogenic CO2 emissions. Here, we present a numerical, multiphysics model, computationally intensified 60-fold with a machine learning a...

The development of electronics is increasingly dependent on low-cost, flexible, solution-processed semiconductors. Colloidal quantum dots are solution-processed semiconducting nanocrystals that have a size-tunable bandgap and can be fabricated on a range of substrates. Here we review developments in colloidal quantum dot electronics, focusing on lu...

Silver (Ag) catalysts enable high selectivity (>90%) in CO2-to-CO conversion at >100 mA cm-2 gold (Au) catalysts are active at lower overpotential, but with lower selectivity (<80%). Here we present an adparticle-functionalized catalyst that combines the benefits of each by uniting Au adparticles on the AgAu interface. Au adparticles modify the lat...

Photoelectrochemical catalysis is an attractive way to provide direct hydrogen production from solar energy. However, solar conversion efficiencies are hindered by the fact that light harvesting has so far been of limited efficiency in the near-infrared region as compared to that in the visible and ultraviolet regions. Here we introduce near-infrar...

Charge carrier transport in colloidal quantum dot (CQD) solids is strongly influenced by coupling among CQDs. The shape of as‐synthesized CQDs results in random orientational relationships among facets in CQD solids, and this limits the CQD coupling strength and the resultant performance of optoelectronic devices. Here, colloidal‐phase reconstructi...

Translating the high power conversion efficiencies of single-junction perovskite solar cells in their classic, non-inverted (n-i-p) architecture to efficient monolithic n-i-p perovskite/silicon tandem solar cells with high current densities has been a persistent challenge due to the lack of low-temperature processable, chemically-insoluble contact...

The all‐inorganic nature of CsPbI3 perovskites allows to enhance stability in perovskite devices. Research efforts have led to improved stability of the black phase in CsPbI3 films; however, these strategies—including strain and doping—are based on organic‐ligand‐capped perovskites, which prevent perovskites from forming the close‐packed quantum do...

Many of the best-performing perovskite photovoltaic devices make use of 2D/3D interfaces, which improve efficiency and stability – but it remains unclear how the conversion of 3D-to-2D perovskite occurs and how these interfaces are assembled. Here, we use in situ Grazing-Incidence Wide-Angle X-Ray Scattering to resolve 2D/3D interface formation dur...

The renewable-electricity-powered CO 2 electroreduction reaction provides a promising means to store intermittent renewable energy in the form of valuable chemicals and dispatchable fuels. Renewable methane produced using CO 2 electroreduction attracts interest due to the established global distribution network; however, present-day efficiencies an...

Potassium helps CO 2 compete in acid Electrochemical reduction of carbon dioxide (CO 2 ) is a promising means of converting this greenhouse gas into valuable fuels and chemicals. However, two competing reactions restrict the efficiency of this process. In base, much of the CO 2 is trapped as carbonate before reduction; in acid, protons outpace CO 2...

Stable and affordable electrocatalysts are urgently needed to accelerate the transition from conventional fossil fuels to sustainable energy resources such as solar and wind. Over the last two decades, the electrocatalytic splitting of water, and carbon dioxide reduction to hydrocarbons have received great attention, however approximately 90% of th...

Semiconducting thin films made from nanocrystals hold potential as composite hybrid materials with new functionalities. With nanocrystal syntheses, composition can be controlled at the sub-nanometer level, and, by tuning size, shape, and surface termination of the nanocrystals as well as their packing, it is possible to select the electronic, phono...

Quantum‐dot‐in‐perovskite solids (QDiP), wherein colloidal quantum dots (CQDs) are inside bulk hybrid halide perovskites, have emerged as a novel class of semiconductors with mixed dimensionalities. The interfacial quality achieved enables good charge transport from the perovskite matrix to the embedded dots and leads to photon interaction function...

The electrochemical conversion of CO 2 to methane provides a means to store intermittent renewable electricity in the form of a carbon-neutral hydrocarbon fuel that benefits from an established global distribution network. The stability and selectivity of reported approaches reside below technoeconomic-related requirements. Membrane electrode assem...

Membrane electrode assembly (MEA) electrolyzers offer a means to scale up CO 2 -to-ethylene electroconversion using renewable electricity and close the anthropogenic carbon cycle. To date, excessive CO 2 coverage at the catalyst surface with limited active sites in MEA systems interferes with the carbon-carbon coupling reaction, diminishing ethylen...

The all‐inorganic nature of CsPbI 3 perovskites offers an avenue to enhance stability in perovskite devices. Concerted research efforts have led to improved stability of the black phase in CsPbI 3 films; however, these strategies – including strain and doping – are based on organic‐ligand‐capped perovskites, which prevent perovskites from forming t...

The development of reagentless sensors that can detect molecular analytes in biological fluids could enable a broad range of applications in personalized health monitoring. However, only a limited set of molecular inputs can currently be detected using reagentless sensors. Here, we report a sensing mechanism that is compatible with the analysis of...

In hydrogen production, the anodic oxygen evolution reaction (OER) limits the energy conversion efficiency and also impacts stability in proton-exchange membrane water electrolyzers. Widely used Ir-based catalysts suffer from insufficient activity, while more active Ru-based catalysts tend to dissolve under OER conditions. This has been associated...

Electro-optic (EO) modulation is of interest to impart information onto an optical carrier. Inorganic crystals-most notably LiNbO3 and BaTiO3-exhibit EO modulation and good stability, but are difficult to integrate with silicon photonic technology. Solution-processed organic EO materials are readily integrated but suffer from thermal degradation at...

Efficient thermoelectric generators require further progress in developing n-type semiconductors that combine low thermal conductivity with high electrical conductivity. By embedding colloidal quantum dots (CQDs) in a metal halide matrix (QDMH), the metal halide matrix can enhance phonon scattering, thus suppressing thermal transport; however, simu...

Stability of perovskite-based photovoltaics remains a topic requiring further attention. Cation engineering influences perovskite stability, with the present-day understanding of the impact of cations based on accelerated ageing tests at higher-than-operating temperatures (e.g. 140°C). By coupling high-throughput experimentation with machine learni...

Engineering halide perovskites through alloying allows synthesis of materials having tuned electronic and optical properties; however, synthesizing many of these alloys is hindered by the formation of demixed phases arising due to thermodynamically unstable crystal structures. Methods have been developed to make such alloys, such as solid‐phase rea...

Inside front cover image: In the electrocatalytic CO2 reduction devices, especially in flow cell reactors, undesired liquid products crossover from cathode to anode will reduce device productivity and impair the quantitative evaluation of the catalytic performance. The authors reviewed several methods to suppress liquid products crossover including...

Perovskites with the multi‐cation composition of cesium (Cs), methylammonium (MA), and formamidinium (FA) (CsMAFA) are pursued for their high power conversion efficiencies, but they are limited by their thermal stability. To withstand damp‐heat accelerated aging MA‐free compositions such as CsFA are of interest, but these exhibit lower carrier diff...

CO₂ electroreduction provides a route to convert waste emissions into chemicals such as ethylene (C₂H₄). However, the direct transformation of CO₂-to-C₂H₄ suffers from CO₂ loss to carbonate, consuming up to 72% of energy input. A cascade approach—coupling a solid-oxide CO₂-to-CO electrochemical cell (SOEC) with a CO-to-C₂H₄ membrane electrode assem...

Mixed cation perovskites have improved stability, but cation alloying enables the formation of separated phases, as well as leading to new decomposition pathways. Here, using photothermal infrared microscopy, we report degradation mechanisms in FA0.85Cs0.15PbI3, a study enabled by our ability to resolve the location of formamidinium (FA) cations wi...

New technologies are required to electrocatalytically convert carbon dioxide (CO2) into fuels and chemicals at near-ambient temperatures and pressures more effectively. One particular challenge is mediating the electrochemical CO2 reduction reaction (CO2RR) at low cell voltages while maintaining high conversion efficiencies. Anion exchange membrane...

The electrochemical conversion of CO2 produces valuable chemicals and fuels. However, operating at high reaction rates produces locally alkaline conditions that convert reactant CO 2 into cell-damaging carbonate salts. These salts precipitate in the porous cathode structure, block CO2 transport, reduce reaction efficiency, and render CO2 electrolys...

Bifacial monolithic perovskite/silicon tandem solar cells exploit albedo—the diffuse reflected light from the environment—to increase their performance above that of monofacial perovskite/silicon tandems. Here we report bifacial tandems with certified power conversion efficiencies >25% under monofacial AM1.5G 1 sun illumination that reach power-gen...

In lead-halide perovskites, antibonding states at the valence band maximum (VBM)-the result of Pb 6s-I 5p coupling-enable defect-tolerant properties; however, questions surrounding stability, and a reliance on lead, remain challenges for perovskite solar cells. Here, we report that binary GeSe has a perovskite-like antibonding VBM arising from Ge 4...

The development of new methods for direct viral detection using streamlined and ideally reagent-free assays is a timely and important, but challenging, problem. The challenge of combatting the COVID-19 pandemic has been exacerbated by the lack of rapid and effective methods to identify viral pathogens like SARS-CoV-2 on-demand. Existing gold standa...

The electrosynthesis of value‐added multicarbon products from CO2 is a promising strategy to shift chemical production away from fossil fuels. Particularly important is the rational design of gas diffusion electrode (GDE) assemblies to react selectively, at scale, and at high rates. However, the understanding of the gas diffusion layer (GDL) in the...

In recent years, metal halide perovskites (MHPs) have attracted attention as semiconductors that achieve desirable properties for optoelectronic devices. However, two challenges—instability and the regulated nature of Pb —remain to be addressed with commercial applications. The development of Pb-free halide double perovskite (HDP) materials has gai...

Machine learning models of materials$^{1-5}$ accelerate discovery compared to ab initio methods: deep learning models now reproduce density functional theory (DFT)-calculated results at one hundred thousandths of the cost of DFT$^{6}$. To provide guidance in experimental materials synthesis, these need to be coupled with an accurate yet effective s...

Coupling electrochemical CO2 reduction (CO2R) with a renewable energy source to create high‐value fuels and chemicals is a promising strategy in moving toward a sustainable global energy economy. CO2R liquid products, such as formate, acetate, ethanol, and propanol, offer high volumetric energy density and are more easily stored and transported tha...

Rare CD19+ leukemic B cells present in purified T cell populations can cause disease relapse and even the failure of CD19-targeting CAR-T therapy as these rare cells have the ability to self-mask their surface CD19 and escape from the recognition of T cells. It is therefore critical to efficiently detect and robustly deplete rare leukemic B cells i...

Fast and sensitive infrared (IR) photodetection is of interest for depth imaging that is fundamental to machine vision, augmented reality, and autonomous driving. Colloidal quantum dots (CQDs) are appealing candidates for this goal: in contrast with III–V semiconductors, they offer facile tuning of IR absorption and enable ease of integration via s...

Solvents play a crucial role in electrocatalytic reactions, yet existing simulation methods for the catalyst-solvent interface are either too slow or too inaccurate. Goddard et. al. report a quantum mechanics/molecular mechanics method for electrocatalysis simulations which they show to be accurate and efficient.

Molecular-level features of tumours can be tracked using single-cell analyses of circulating tumour cells (CTCs). However, single-cell measurements of protein expression for rare CTCs are hampered by the presence of a large number of non-target cells. Here, we show that antibody-mediated labelling of intracellular proteins in the nucleus, mitochond...

CO2 capture technologies based on chemisorption present the potential to lower net emissions of CO2 into the atmosphere. The electrochemical upgrade of captured CO2 to value-added products would be particularly convenient. Here we find that this goal is curtailed when the adduct of the capture molecule with CO2 fails to place the CO2 sufficiently c...

Metal halide perovskites have emerged as promising candidates for solution‐processed laser gain materials, with impressive performance in the green and red spectral regions. Despite exciting progress, deep‐blue — an important wavelength for laser applications—remains underexplored; indeed, cavity integration and single‐mode lasing from large‐bandga...

Catalytic hydrogenation of bio-oil provides an avenue to produce renewable chemicals. To this end, electrocatalytic hydrogenation is especially interesting when powered using low-carbon electricity; however, it has to date lacked the needed selectivity: when hydrogenating bio-oil to oxygenated hydrocarbons, for example, it reduces the desired oxyge...

Electrical‐to‐optical signal conversion is widely employed in information technology and is implemented using on‐chip optical modulators. State‐of‐the‐art modulator technologies are incompatible with silicon manufacturing techniques: inorganic nonlinear crystals such as LiNbO3 are integrated with silicon photonic chips only using complex approaches...

In the electrochemical CO2 reduction reaction (CO2RR), control over the binding of intermediates is key for tuning product selectivity and catalytic activity. Here we report the use of reticular chemistry to control the binding of CO2RR intermediates on metal catalysts encapsulated inside metal-organic frameworks (MOFs), thereby allowing us to impr...

We report formate production via CO2 electroreduction at a Faradaic efficiency (FE) of 93% and a partial current density of 930 mA cm-2, an activity level of potential industrial interest based on prior techno-economic analyses. We devise a catalyst synthesized using InP colloidal quantum dots (CQDs): the capping ligand exchange introduces surface...

Electroreduction uses renewable energy to upgrade carbon dioxide to value-added chemicals and fuels. Renewable methane synthesized using such a route stands to be readily deployed using existing infrastructure for the distribution and utilization of natural gas. Here we design a suite of ligand-stabilized metal oxide clusters and find that these mo...

In further advancing display technologies, especially for improved blue emitters, to engineer the bandgap of promising semiconductors such as hybrid perovskites is important. Present-day methods for tuning the bandgaps of perovskites, such as the incorporation of mixed halide anions, suffer drawbacks such as phase separation and difficulty in synth...

Multimetal oxyhydroxides have recently been reported that outperform noble metal catalysts for oxygen evolution reaction (OER). In such 3d-metal-based catalysts, the oxidation cycle of 3d metals has been posited to act as the OER thermodynamic-limiting process; however, further tuning of its energetics is challenging due to similarities among the e...