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The Makecourse-Art is a makerspace designed to promote undergraduate students' aesthetic design skills as well as functional design skills using an interdisciplinary team approach at the University of South Florida. To overcome the unique challenges of the Makecourse (earlier version) and to maximize students' design efforts working on an engineering project in the classroom, the Makecourse-Art incorporated a flipped classroom model utilizing two instructional methods with corresponding activities. First, the explicit form of instruction is delivered through asynchronous video lectures/ tutorials, including topics such as Arduino programming, CAD modeling with the Autodesk Maya, Mudbox, and coding skills. Second, interactive team-based classroom activities are offered to students based on student-centered learning theories such as peer-assisted collaborative learning and problem-based learning. In this paper, we present the design case of the Makecourse-Art with detailed descriptions of the components, and explain the key design decisions, obstacles during the design process, and how the challenges were resolved. In addition, we provide step-by-step examples of students' engineering design experiences with visual images.

This paper discusses the investigation of the dipole formation at In2O3|TiO2 heterojunctions depending on preparation conditions, i.e., cleaning methods. In2O3 films were deposited using atomic layer deposition (ALD) onto solvent and in situ cleaned anatase and rutile film substrates. The interface dipole strength and film thickness were evaluated by photoemission spectroscopy. Our results indicate the formation of a large intrinsic and film thickness dependent interface dipole that reaches its maximum strength at monolayer thick ALD films. In addition, it was observed that UV photoelectron spectroscopy measurements introduced UV induced surface hydroxylation, which resulted in dipole potentials of -0.70 eV and -0.50 eV on solvent cleaned anatase and rutile, respectively. The overlayers also introduced small amounts of band bending (~0.10 eV) at the interfaces. Taking these effects into account, the total dipole strength at monolayer thick In2O3 films was determined to be -0.96 eV for solvent cleaned anatase and rutile and -0.81 eV for in situ cleaned rutile. The deposition of single ALD cycles on differently cleaned rutile substrates resulted in similar work function values, suggesting little influence of the sample preparation method prior to ALD deposition on the dipole formation. This was assigned to the fact that ALD oxides benefit from ambient water related contamination by integrating the molecules into the growing ALD layer. Highest initial growth was observed on solvent cleaned rutile, followed by in situ cleaned rutile and solvent cleaned anatase. The In2O3 growth converged at 0.3Å/c past the nucleation regime. [ABSTRACT FROM AUTHOR]

Organic-inorganic nanoparticle molecular hybrid materials are interesting candidates for improving exciton separation in organic solar cells. The orbital alignment at the internal interface of cadmium selenide (ArS-CdSe) hybrid materials functionalized with covalently attached arylthiolate moieties was investigated through X-ray photoemission spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS). A physisorbed interface between arylthiol (ArSH) ligands and CdSe nanoparticles was also investigated for comparison. This interface was created via a multi-step thin film deposition procedure in-vacuo, where the surface was characterized after each experimental step. This enabled the direct comparison of ArSH/CdSe interfaces produced via physisorption and ArSCdSe covalently attached hybrid materials, which rely on a chemical reaction for their synthesis. All material depositions were performed using an electrospray deposition, which enabled the direct injection of solution-originating molecular species into the vacuum system. This method allows XPS and UPS measurements to be performed immediately after deposition without exposure to the atmosphere. Transmission electron microscopy was used to determine the morphology and particle size of the deposited materials. Ultraviolet-visible spectroscopy was used to estimate the optical band gap of the CdSe nanoparticles and the HOMO-LUMO gap of the ArSH ligands. These experiments showed that hybridization via covalent bonds results in an orbital realignment at the ArSH/ CdSe interface in comparison to the physisorbed interface. The orbital alignment within the hybrid caused a favorable electron injection barrier, which likely facilitates exciton-dissociation while preventing charge-recombination. [ABSTRACT FROM AUTHOR]

The poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV)/poly(3-hexylthiophene) (P3HT) heterojunction was investigated by photoemission spectroscopy. The orbital line-up at the MEH-PPV/P3HT heterojunction was determined based on the data of X-ray and ultra-violet photoemission measurements. The results were discussed with reference to the Induced Density of Interface States (IDIS) and integer charge transfer models. The predicted interface orbital line-up by IDIS is in agreement with measured energy alignment of the investigated interface. This suggests the IDIS model is also valid for polymer/polymer heterojunctions. [ABSTRACT FROM AUTHOR]

Microplasma-assisted gas-phase nucleation has emerged as an important new approach to produce high-purity, nanometer-sized, and narrowly dispersed particles. This study aims to integrate this technique with vacuum conditions to enable synthesis and deposition in an ultrahigh vacuum compatible environment. The ultimate goal is to combine nanoparticle synthesis with photoemission spectroscopy-based electronic structure analysis. Such measurements require in vacuo deposition to prevent surface contamination from sample transfer, which can be deleterious for nanoscale materials. A homebuilt microplasma reactor was integrated into an existing atomic layer deposition system attached to a surface science multi-chamber system equipped with photoemission spectroscopy. As proof-of-concept, we studied the decomposition of ferrocene vapor in the microplasma to synthesize iron oxide nanoparticles. The injection parameters were optimized to achieve complete precursor decomposition under vacuum conditions, and nanoparticles were successfully deposited. The stoichiometry of the deposited samples was characterized in situ using X-ray photoelectron spectroscopy indicating that iron oxide was formed. Additional transmission electron spectroscopy characterization allowed the determination of the size, shape, and crystal lattice of the particles, confirming their structural properties. [ABSTRACT FROM AUTHOR]

The Al/poly(3-hexylthiophene) (P3HT) and Ag/P3HT interfaces were investigated using photoemission spectroscopy in combination with in situ thin-film deposition. The P3HT thin films were deposited directly into high vacuum from solution on the two metal substrates using an electrospray system and characterized via photoemission spectroscopy. The electronic structure and charge injection barriers at these interfaces were determined from the evaluation of the resulting spectra sequences. A linear correlation between barrier heights and substrate work functions was observed from the collected data in combination with previously published results, suggesting that the 'Induced Density of Interfaces States' model for small molecular materials is also valid for conjugated polymer interfaces. The corresponding P3HT 'screening factor' as well as its charge neutrality level was determined to be 0.48 and 3.44 eV, respectively. [ABSTRACT FROM AUTHOR]

Zinc indium tin oxide (ZITO) transparent conductive oxide layers were deposited via radio frequency (RF) magnetron co-sputtering at room temperature. A series of samples with gradually varying zinc content was investigated. The samples were characterized with x-ray and ultraviolet photoemission spectroscopy (XPS, UPS) to determine the electronic structure of the surface. Valence and conduction bands maxima (VBM, CBM), and work function were determined. The experiments indicate that increasing Zn content results in films with a higher defect rate at the surface leading to the formation of a degenerately doped surface layer if the Zn content surpasses ∼50%. Furthermore, the experiments demonstrate that ZITO is susceptible to ultraviolet light induced work function reduction, similar to what was earlier observed on ITO and TiO2 films. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cells are typically prepared under ambient conditions and contamination is inevitably introduced during the fabrication process. Hence, the electronic structure and charge injection properties of the indium tin oxide (ITO)/nanocrystalline titanium dioxide (TiO2) interface was studied by photoemission spectroscopy (PES) in the presence of environmental contaminants. The interface was formed by in situ multi-step electrospray thin film deposition of TiO2 nanoparticles onto ITO substrates cleaned prior in solvent under ambient conditions. In between deposition steps, the samples were characterized with PES yielding the band line-up at the ITO/TiO2 interface. In addition, the band line-up before and after annealing of the TiO2 layer was determined. The results of these measurements have in common that there are only small charge injection barriers between the valence bands of the oxides (∼0-0.2 eV), but more significant barriers for electron injection from TiO2 to ITO (∼0.3-0.5 eV), which has the potential to affect the performance of solar cell device structures. Another focus of the experiments was to investigate whether an earlier reported work function lowering measurement artifact occurring during ultraviolet photoemission spectroscopy (UPS) measurements on environmentally contaminated metal oxide surfaces would affect the characterization of ITO/TiO2 interfaces. For this purpose additional band line-up measurements using low intensity x-ray photoemission spectroscopy (LIXPS) were performed. LIXPS has been demonstrated to not cause the artifact, i.e., can be used to detect its occurrence. The results of these experiments show that the UV-induced work function reduction is not observed on the annealed interface, but that at contaminated interfaces care must be taken during data evaluation to take the artifact into account. [ABSTRACT FROM AUTHOR]

The band line-up and the chemical interaction at the CdTe/NbSe2 interface were investigated with photoemission spectroscopy. NbSe2 is a layered metal dichalcogenide with metallic properties and a large work function. This makes it a potential candidate as back contact material for CdTe thin film solar cells. The interface was investigated by stepwise in situ deposition of NbSe2 and subsequent characterization with x-ray and ultraviolet photoemission spectroscopy. The experiments showed that Te and Se interdiffuse at the interface, causing the formation of a graded diffusion layer. The resulting band alignment indicates the formation of an interface dipole leading to a midband gap alignment of the NbSe2 Fermi level. [ABSTRACT FROM AUTHOR]

Inverse photoemission spectroscopy (IPES) enables the characterization of the density of states of unoccupied energy states above the Fermi level. However, due to the relatively high electron currents required to achieve useful signal to noise ratios, sample damage is a concern. Regioregular poly(3-hexylthiophene) (rr-P3HT) was used to systematically study the influence of electron radiation during IPES measurements on a prototypical conductive polymer. A series of IPES measurements exposing the samples to a range of electron fluxes was performed. An analysis of the electronic structure and the morphology showed that significant changes occurred in the investigated samples depending on the electron flux. X-ray diffraction results revealed that the root cause of the spectral changes is most likely related to crystallization of the film in an edge-on orientation. This was confirmed by Raman spectroscopy where both the C-C and C=C stretch modes shifted to lower frequencies after 5 IPES scans indicating a more ordered molecular structure. The observation of these stretch modes even after exposure to higher electron flux indicates that the main chemical structure of the P3HT molecules remains mostly intact during the IPES measurements. The absence of significant changes in C 1s and S 2p photoemission core level lines also confirmed this conclusion. [ABSTRACT FROM AUTHOR]

Harvesting solar energy as a carbon free source can be a promising solution to the energy crisis and environmental pollution. Biophotovoltaics seek to mimic photosynthesis to harvest solar energy and to take advantage of the low material costs, negative carbon footprint, and material abundance. In the current study, we report on a combination of zinc oxide (ZnO) nanowires with monolayers of photosynthetic reaction centers which are self-assembled, via a cytochrome c linker, as photoactive electrode. In a three-probe biophotovoltaics cell, a photocurrent density of 5.5 μA cm -2 and photovoltage of 36 mV was achieved, using methyl viologen as a redox mediator in the electrolyte. Using ferrocene as a redox mediator a transient photocurrent density of 8.0 μA cm -2 was obtained, which stabilized at 6.4 μA cm -2 after 20 s. In-depth electronic structure characterization using photoemission spectroscopy in conjunction with electrochemical analysis suggests that the fabricated photoactive electrode can provide a proper electronic path for electron transport all the way from the conduction band of the ZnO nanowires, through the protein linker to the RC, and ultimately via redox mediator to the counter electrode.