Aoife Henry (PhDElEngr‘24) is optimizing technology for wind and solar energy operations. The graduate is leading Zentus, a startup she founded that addresses a

Improving the properties of perovskite quantum dots (QDs) for quantum-light applications such as single photon emission requires a systematic understanding of the influence of ligand surface chemistry on single particle properties including line width and photoluminescence (PL) blinking. Here, we investigate the influence of ligand exchange on both the optical and structural properties of the single QDs. We examine PL blinking using a wide-field fluorescence microscope with ligand-exchanged QDs. We find that the zwitterionic ligands lecithin and phosphoethanolamine (PEA-C8C12) reduce blinking compared to dodecylammonium bromide (DDAB) and a bidentate dicationic quaternary ammonium bromide (DC) ligands, which have mono- and bidentate cationic head groups, respectively. The champion PEA-C8C12 shows a nonblinking fraction of 0.21, compared to 0.01 for the cationic-capped QDs. We further investigate the effect of ligand capping on low-temperature line width. We probe single particle line widths and show that zwitterionic PEA-C8C12 and lecithin outperform the cationic surface ligands for ligand-exchanged samples, having a narrower average single particle line width (24 meV for lecithin and 18 meV for PEA-C8C12 compared to 39 meV for DC-capped and 42 meV for DDAB-capped QDs) over long integration times. We rationalize these findings by quantifying ligand surface coverage using nuclear magnetic resonance, observing that QDs capped by zwitterions have higher ligand surface coverage (6.5 ± 1.6 for lecithin and 7.4 ± 1.9 ligands/nm2 for PEA), consistent with their superior performance at the single particle level. These line width and blinking results show that zwitterionic ligands are a preferable design strategy for reducing PL blinking and improving single particle line widths.

Thin film synthesis allows for the potential to orient crystals in different orientations, permitting measurement of orientation-dependent material aspects such

Reverse osmosis (RO) membranes used for wastewater reuse are vulnerable to organic fouling, necessitating effective pretreatment for a sustainable operation. Here, we evaluate the potential of 222 nm UV irradiation as a chemical-free pretreatment to transform organic matter from secondary wastewater effluent prior to RO. 222 nm UV generally achieved greater fouling control than conventional 254 nm UV with hydrogen peroxide, reducing flux decline from wastewater effluent fouling by 60% (fluence of 400 mJ/cm2) versus 29% for 254 nm + H2O2 (fluence of 1000 mJ/cm2), relative to untreated wastewater. Size-exclusion chromatography revealed that both UV wavelengths decreased high molecular weight (MW) organics, but only 222 nm UV substantially degraded medium-low MW TOC fractions, which correlated with fouling reduction. In contrast, we observed significant protein conformational changes induced by 222 nm UV could increase fouling for certain feed waters and treatment conditions. Characterization of the fouled membrane surface showed that 222 nm UV-treated water formed a more porous fouling layer with more oxidized carbon than did untreated and 254 nm UV-treated waters. Overall, this work found 222 nm UV to be a promising, chemical-free pretreatment to RO and underscores the importance of water-specific process optimization.

Nickel oxide (NiOx) is among the few p-type metal oxide semiconductors considered a strong candidate for hole transport layers in halide perovskite solar cells (PSCs). However, its reactivity with per...

When perovskite solar cells (PSCs) are subjected to reverse bias, they often abruptly pass large current densities through localized film defects. The large, localized current induces heating that qui...

Low catalyst loadings pose challenges to performance stability in proton exchange membrane (PEM) water electrolysis over extended operation. To study the impact of degradation mechanisms and voltage loss rates, different stress tests are applied to membrane electrode assemblies. Potential cycling conditions were observed to induce higher degrees of iridium (Ir) oxide crystallization, ionomer degradation, and catalyst layer (CL) thinning, which likely contributed to higher kinetic loss rates. On the other hand, while Ir migrating into the PEM (Ir band) generally impairs performance, the interconnected and more uniform Ir band formed under a constant 2 V hold may allow for Ir at the catalyst/membrane interface to remain electronically connected and kinetically accessible, as well as indicate greater Ir site access during the applied stressor. The 2 V hold also demonstrates improved kinetic durability through a lower Tafel slope, faster polarization kinetics, and reduced charge transfer resistance. In contrast, potential cycling caused the migration of disconnected Ir agglomerates into the membrane bulk and created a steady increase in charge transfer resistance, a more dramatic decrease in capacitance (46.7% loss), and significant damage to the surrounding ionomer, indicating a decline in both the quality and quantity of active sites in the anode CL. This work underscores the distinct degradation pathways associated with load holds versus cycling, highlighting the role of catalyst–ionomer interactions in kinetic performance and long-term stability. These insights can inform operational strategies for PEM electrolyzers powered by intermittent energy sources, aiming to minimize efficiency losses over extended operation.

Semiconducting polymers are being explored for electrochemical and photoelectrochemical energy transformation and storage applications. For these applications, it is critical to understand how ion insertion from the electrolyte into polymer electrodes modulates the polymer electronic structure and electron doping levels. This study explores electrochemical cation insertion in the n-type conjugated redox polymer P90, composed of alternating naphthalene diimide (NDI) acceptor and bithiophene (T2) donor units, where the NDI units are functionalized with heptaethylene glycol (HEG, 90%) and 2-octyl dodecyl (OD, 10%) side chains. By combining in situ techniques (UV–vis absorption and Raman spectroscopies with electrochemistry), structural analysis using ex situ grazing-incidence wide-angle X-ray scattering (GIWAXS), and density functional theory (DFT) calculations, we reveal that dications enable negative polaron and bipolaron formation in the P90 at less reducing potentials while supporting more bipolaron formation than the monocations; moreover, larger dications with smaller hydrated radii increase the maximum P90 electron doping level. We also determine that the monocations lead to more thermodynamically stabilized polarons compared with the dications. These findings highlight the critical role of cation identity in tuning electrochemical charging, charge stabilization, and electronic structure of n-type conjugated redox polymers, providing guidance on the rational design of polymer-based (photo)electrochemical applications.

We report the modulation of molecular charge transfer in a bay-substituted perylene diimide derivative embedded in a planar distributed Bragg reflector microcavity. Angle-resolved reflectance spectra ...

Metal halide perovskite films in the top cell of triple-junction tandems require bandgaps around 2.0 eV to achieve current matching, assuming that the middle absorbing layer is the commonly used FAPbI3 composition and the bottom cell has a bandgap around 1.1 eV. Unfortunately, mixed organic/inorganic metal halide perovskites that have the necessary Br content to reach a bandgap of 2.0 eV segregate into iodine-rich and bromine-rich phases under illumination, limiting their obtainable voltage. Previous reports have shown improved photostability using either Cs-based inorganic compositions or Cl incorporation on the X-site. Here, we investigate the inorganic triple halide compositional space CsPb(I1–x–yBryClx)3 where bandgaps near 2.0 eV are expected based on the knowledge that CsPbI2Br has a bandgap of 1.90 eV. Incorporation of Cl occurs readily for x ≤ 0.07–0.10 within perovskites with a Br content of 0.3 ≤ y ≤ 0.42. When x >0.1, X-ray diffraction and photoluminescence (PL) measurements indicate that multiple compositional phases form. We hypothesize that the variable sizes of the three halide ions are not supported within the rigid Cs lattice, resulting in the formation of multiple compositional phases. The photoluminescence quantum yield of the single-phase compositional space─CsPb(I1–x–yBryClx)3 where x ≤ 0.07─was typically 0.001–0.004%, most likely as a result of a high defect density, including mobile iodine species. PL light-soaking measurements of many perovskite compositions with bandgaps in the range of 1.89–2.05 eV demonstrate that phase segregation occurs when initial bandgaps are above 1.95 eV regardless of halide content: indicating further iodide oxidation and corresponding migration under illumination. The conclusion is that further compositional or additive engineering is necessary for the development of inorganic triple halide compositions that accomplish the elusive goal of fabricating high-quality and photostable 2.0 eV films for use in multijunction tandems.

Phosphonic acid (PA)–based interlayers used in metal-halide perovskite solar cells (PSCs) can suffer from instability at elevated temperatures. We report that the acidic protons of PAs weakly bound to...

Eleven students participated in this year’s final competition for a chance at prize money and a chance to represent CU Boulder at the regional competition.

Founded by the University of Queensland in 2008, the Three Minute Thesis (3MT) is an academic competition that cultivates students’ presentation and science

CHEMISTRY OF MATERIALS, 2026, ASAP

JANUARY 2026