Ortho-Litho Film

The purpose of this design was to create modern surface design employing traditional analog photography and chemistry technology with Ortho Litho film, a series of chemical and light exposures, cotton yarn, and sand

Collected, Cut and Recreated Dress

The purpose of this design was to create an eco-friendly dress made out of recycled materials, American Spirit cigarette boxes; the design was inspired by the concept of sustainability and motifs of Native American textiles

The thermal equation of state of FeTiO_3 ilmenite based on in situ X-ray diffraction at high pressures and temperatures

We present in situ measurements of the unit-cell volume of a natural terrestrial ilmenite (Jagersfontein mine, South Africa) and a synthetic reduced ilmenite (FeTiO_3) at simultaneous high pressure and high temperature up to 16 GPa and 1273 K. Unit-cell volumes were determined using energy-dispersive synchrotron X-ray diffraction in a multi-anvil press. Mössbauer analyses show that the synthetic sample contained insignificant amounts of Fe^(3+) both before and after the experiment. Results were fit to Birch-Murnaghan thermal equations of state, which reproduce the experimental data to within 0.5 and 0.7 GPa for the synthetic and natural samples, respectively. At ambient conditions, the unit-cell volume of the natural sample [V_0 = 314.75 ± 0.23 (1 ) Å^3] is significantly smaller than that of the synthetic sample [V_0 = 319.12 ± 0.26 Å^3]. The difference can be attributed to the presence of impurities and Fe^(3+) in the natural sample. The 1 bar isothermal bulk moduli K_(T0) for the reduced ilmenite is slightly larger than for the natural ilmenite (181 ± 7 and 165 ± 6 GPa, respectively), with pressure derivatives K_0' = 3 ± 1. Our results, combined with literature data, suggest that the unit-cell volume of reduced ilmenite is significantly larger than that of oxidized ilmenite, whereas their thermoelastic parameters are similar. Our data provide more appropriate input parameters for thermo-chemical models of lunar interior evolution, in which reduced ilmenite plays a critical role

Efficient and semi-transparent perovskite solar cells using a room-temperature processed MoOx/ITO/Ag/ITO electrode

In order to achieve semi-transparency in perovskite solar cells, the electrode materials must be as transparent as possible. In this work, MoOx/ITO/Ag/ITO (MoOx/IAI) thin films with high average transmittance of 79.90% between 400 nm and 900 nm were introduced as the top transparent electrode to explore its influences on optoelectronic properties of the fabricated perovskite solar cells. MoOx has been demonstrated previously as protection from sputtering damage using a conventional ITO top electrode, however it is shown here to provide protection from a sputtered IAI film that provides superior transparency and conductivity and is deposited using more favourable low temperature processing conditions. MoOx and Ag were thermally evaporated and ITO was radio-frequency magnetron sputtered at room temperature. The resulting semi-transparent solar cells showed power conversion efficiency of 12.85% (steady-state efficiency of 11.3%) along with a much-reduced degradation rate as compared to the reference device with only a Ag top electrode. With such a combination of performance and transparency, this work shows great promise in application of perovskite solar cells into window glazing products for building integrated photovoltaic applications (BIPV), powering internet of things (IoT) and combining into tandem solar cells with industrially mature photovoltaic technologies such as silicon and copper indium gallium di-selenide (CIGS)

Band-like electron transport in 2D quantum dot periodic lattices: the effect of realistic size distributions

Electron mobility in nanocrystal films has been a controversial topic in the last few years. Theoretical and experimental studies evidencing carrier transport by hopping or showing band-like features have been reported in the past. A relevant factor to analyze transport results is the progressive improvement in quantum dot superlattice fabrication, leading to better regimented structures for which band-like transport would be more relevant. This work presents an efficient model to compute temperature-dependent band-like electronic mobilities in 2D quantum dot arrays when a realistic quantum dot size distribution is considered. Comparisons with experimental results are used to estimate these size distributions, in good agreement with data of the samples

Efficient, stable perovskite solar cells enabled by electrode interface engineering and nanoscale phase stabilization

Thesis (Ph.D.)--University of Washington, 2017-08Semiconducting metal halide perovskites have emerged as a promising solution-processable, photovoltaic material with research cell power conversion efficiencies now exceeding 22% under simulated sunlight. The prototypical composition of this “ABX3” semiconductor is CH3NH3PbI3, in which organic methylammonium cations charge stabilize lead iodide octahedra. Research is underway on mixed component systems with A-site cation combinations of methylammonium, formamidinium, cesium, and rubidium; B-site cations of Pb2+ and Sn2+; and iodide, bromide and chloride anions. Although perovskite solar cells with low-cost fabrication methods have demonstrated impressive power conversion efficiencies, device durability remains a key concern of the technology. In this dissertation, the effect of the anode electrode material on the device lifetime is characterized under constant operating conditions. It is demonstrated that MoOx/Al electrodes are more stable than commonly used Au or Ag electrodes. Interestingly, the enhanced stability of MoOx/Al electrodes is due to the formation of an oxide at the MoOx/Al interface, which likely prevents ion migration between the device layers, as opposed to encapsulation from environmental agents. I also demonstrate a more stable photoactive layer comprised of CsPbI3 quantum dots (QDs). CsPbI3 is the lowest bandgap, all-inorganic lead halide perovskite, and has shown remarkable chemical and thermal stability up to 400 °C. However, bulk and thin film CsPbI3 transitions to the undesired orthorhombic phase when cooled to room temperature. CsPbI3 QDs have unique surface properties which alter the phase transitions and successfully maintain the photoactive cubic phase at room temperature and even well below. In addition to reporting the first demonstration of an all-inorganic CsPbX3 nanocrystal solar cell, I also detail new QD surface treatments that improve the short circuit current density of the devices by doubling the QD film mobility. These advancements led to an NREL-certified QD solar cell efficiency of 13.43% that is currently the record efficiency reported for a QD solar cell of any material system. In this dissertation, I assess operational stability of thin film organic-inorganic perovskite solar cells, fabricate more durable electrodes, develop novel CsPbI3 QD photovoltaic devices and discover new surface modifications to improve charge transport in efficient perovskite QD solar cells