Engineering Commons^™

Electrical Characterization Of Irradiated Semiconducting Amorphous Hydrogenated Boron Carbide, George Glen Peterson

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Semiconducting amorphous partially dehydrogenated boron carbide has been explored as a neutron voltaic for operation in radiation harsh environments, such as on deep space satellites/probes. A neutron voltaic device could also be used as a solid state neutron radiation detector to provide immediate alerts for radiation workers/students, as opposed to the passive dosimetry badges utilized today. Understanding how the irradiation environment effects the electrical properties of semiconducting amorphous partially dehydrogenated boron carbide is important to predicting the stability of these devices in operation. p-n heterojunction diodes were formed from the synthesis of semiconducting amorphous partially dehydrogenated boron carbide on silicon …

Wide Bandgap Organo‐Lead Trihalide Perovskites For Solar Cells, Miao Hu

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Methylammonium lead trihalide perovskite (MAPbX3, where MA is methylammonium, and X is a halide)-based solar cells have been extensively investigated recently, with a demonstrated and certified solar power conversion efficiency (PCE) exceeding 20%. To further boost the PCE beyond the Schockley–Queisser limit, tandem structured solar cells have been investigated based on integrating MAPbX3 and the lower bandgap solar cells. Although the best reported efficiency for this type of tandem cells is not close to the theoretically achievable value, mixed-halide perovskite MAPbBrxI3–x is still one of the most promising candidates as the wide-bandgap light absorber for the tandem application to match …

Efficiency Enhancement In Solution Processed Organic And Organic-Inorganic Hybrid Perovskite Solar Cells, Zhengguo Xiao

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Solution processed thin film photovoltaic devices are one of the most promising renewable energy sources. Organic solar cells have been intensively studied due to their advantages of light-weight, flexibility and low-cost materials and manufacturing. The organic-inorganic hybrid perovskite materials have recently shown great potential application in solar cells. The PCE increased dramatically from 3.8% in 2009 to a certified efficiency of 20.1% in 2014. In this dissertation, we focus on the efficiency enhancement for solution processed organic and organic-inorganic solar cells.

In Chapter 2, I demonstrated that the crystallinity of the ferroelectric polymer P(VDF-TrFE) at the organic active layer/ electrode …

Low Noise, High Detectivity Photodetectors Based On Organic Materials, Fawen Guo

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Organic photodetectors (OPDs) are potentially useful in many applications because of their light weight, flexibility and good form factors. Despite the high detectivities that have been frequently reported for OPDs recently, the application of these OPDs for weak light detection has been rarely demonstrated.

In this thesis, low noise, high gain photodetectors based on organic and ZnO nanoparticles were proposed and demonstrated for highly sensitive UV light detection. The nanocomposite photodetector works in a hybrid mode of photodiode and photoconductor with the transition controlled by the UV light illumination. The nanocomposite detector shows two orders of magnitude higher sensitivity than …

Optical Properties Of Semiconducting Boron Carbide For Neutron Detection Applications, Ravi B. Billa

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Solid state neutron detection devices based on semiconducting boron carbide have the potential for nearly ideal neutron detection effciency for thermal neutrons. The present work is focused on characterizing optical properties of this semiconducting boron carbide material as a step in further development of the material for neutron detection and other applications.

Semiconducting boron carbide films were grown on silicon substrates using plasma enhanced chemical vapor deposition and their optical properties were characterized using variable angle spectroscopic ellipsometry over a wide spectral range, from mid-infrared to vacuum-ultraviolet wavelengths. The effects of deposition substrate temperature and of post-deposition heat treatments on …