Charles Kolodziej

Case Western Reserve University | CWRU · Department of Chemistry

Heterojunction photocatalysts are widely adopted for efficient water splitting, but ion migration can seriously threaten the stability of heterojunctions, as with the well-known low stability of CdS-Cu2‒xS due to intrinsic Cu+ ion migration. Here, we utilize Cu+ migration to design a stratified CdS-Cu2‒xS/MoS2 photocatalyst, in which Cu(I)@MoS2 (Cu...

The spatial heterogeneity of carrier dynamics in mixed halide perovskite CH3NH3PbI3−xClx thin films with a range of different chloride additions is mapped using femtosecond transient absorption microscopy (TAM). The comparison of TAM images of fibrous and granular polycrystalline CH3NH3PbI3−xClx films indicates that the impact of chloride addition...

Replacing current benchmark rare-element photosensitizers with ones based on abundant and low-cost metals such as iron would help facilitate the large-scale implementation of solar energy conversion. To do so, the ability to extend the lifetimes of photogenerated excited states of iron complexes is critical. Here, we present a sensitizer design in...

The spatial heterogeneity of carrier dynamics in polycrystalline metal halide perovskite (MHP) thin films has a strong influence on photovoltaic device performance; however, the underlying cause is not yet clearly understood. Here, the sub‐micrometer scale mapping of charge carrier dynamics in CH3NH3PbI3 thin films using time‐resolved nonlinear opt...

For photovoltaic devices based on hybrid organic-inorganic perovskites thin films, the cell architecture is a vital parameter in defining the macroscopic performance. However, the understanding of the correlation between architecture and carrier dynamics in perovskites thin films has remained elusive. In this work, we utilize concerted materials ch...

In this work, the spatially dependent recombination kinetics of mixed-halide hybrid perovskite CH3NH3Pb(Br1-xClx)3 (0 ≤ X ≤ 0.19) single crystals are investigated using time-resolved photoluminescence spectroscopy with one- and two-photon femtosecond laser excitation. The introduction of chloride by substituting a fraction of the bromide leads to a...

Transition metal dichalcogenides (TMDCs), such as MoS 2 , WS 2 , WSe 2 and MoSe 2 , exhibit a special structure in which a transition metal layer sandwiched between two chalcogen atomic layers. The in-plane covalent bonds between neighboring layer are strong and interplane van der Waals forces which keep the layer together are relatively weak. Espe...

Two novel 2D bisthienoacenes with annulated thiophene units at different positions were developed. Both 1,2‐ and 1,4‐addition of the α,β‐unsaturated ketone moieties lead to the major formation of four‐fold alkylsilylethynyl substituted 2D heteroacenes (namely BTT‐4TIPS and BTP‐4TIPS). The photophysical, electrochemical properties, crystal packing s...

Excitonically-coupled bacteriochlorin (BC) dimers constitute a primary electron donor (special pair) in bacterial photosynthesis and absorbing units in light-harvesting antenna. However, the exact nature of the excited state of these dyads is still not fully understood. Here, we report a detailed spectroscopic and computational investigation of a s...

In this study we prepared zinc oxide (ZnO) nanoparticles using the polyol method with zinc acetate and/or sodium acetate in a propylene glycol medium with varied hydrolysis reaction time (10, 60 and 300 min). It was observed that the hydrolysis reaction time and the concentration of acetate ions had a strong effect on the morphology and size of ZnO...

Combined optical and electronic loss analysis is applied in comparing MAPbI3 and MAPbI3−xClx as light absorbers in both planar and mesoporous TiO2 absorber scaffolds in order to determine the specific effects of these architectural variations on energy-dependent loss mechanisms in perovskite-sensitized solar cells. A transfer matrix model is used t...

Over the past several decades, nanotechnology has contributed to the progress of biomedicine, biomarker discovery, and the development of highly sensitive electroanalytical / electrochemical biosensors for in vitro and in vivo monitoring, and quantification of oxidative and nitrosative stress markers like reactive oxygen species (ROS) and reactive...

Perovskite films were prepared using single step solution deposition at different annealing temperatures and annealing times. The crystal structure, phases and grain size were investigated with XRD, XPS and SEM/EDX. The prepared films show a typical orientation of tetragonal perovskite phase and a gradual transition at room temperature from the yel...