Optical and transport properties of organic and organometal halide perovskite semiconductors

A disadvantage of current day’s electronic and optoelectronic applications is that the production cost of the technology is relatively high, and the production methods are not very environmental friendly. Therefore, there is a worldwide effort to discover and develop new technological materials that are not hampered by these drawbacks, and to understand their fundamental properties. This thesis focuses on two classes of materials which show the promising possibility to develop a variety of low-cost and environmentally favorable photo-electric applications: organic semiconductors and organometal halide perovskite semiconductors. Transport and photo-physical properties of representative materials from these classes have been investigated using a variety of experimental methods. Apart from reporting on a study of the degree of conjugation in benzothiadiazole-carbazole molecules and the behavior of photo-excited charges in microcrystalline CH3NH3PbI3 films, this thesis reports on the development of a novel approach to investigate ambipolar charge transport properties of organic semiconductors (the so-called charge selective CELIV method). Application of this method to archetypical organic semiconductor films elucidated the role of shallow and deep trap states on the transport properties in P3HT (poly (3-hexylthiophene)): PCBM (Phenyl C61-Butyric Acid Methyl ester) blends, and led to the discovery of a controllable extremely long (hours) lifetime of photo-excited charge carriers in thin films of NPB ((N,N’-Di(1-naphthyl)-N,N’-diphenyl-(1,1’-biphenyl)-4,4’-diamine)), which shows promise for applications in low light level detector or organic memory technologies

Shock-induced breaking of the nanowire with the dependence of crystallographic orientation and strain rate

The failure of the metallic nanowire has raised concerns due to its applied reliability in nanoelectromechanical system. In this article, the breaking failure is studied for the [100], [110], and [111] single-crystal copper nanowires at different strain rates. The statistical breaking position distributions of the nanowires have been investigated to give the effects of strain rate and crystallographic orientation on micro-atomic fluctuation in the symmetric stretching of the nanowires. When the strain rate is less than 0.26% ps-1, macro-breaking position distributions exhibit the anisotropy of micro-atomic fluctuation. However, when the strain rate is larger than 3.54% ps-1, the anisotropy is not obvious because of strong symmetric shocks

Search for vector-like leptons at a Muon Collider

A feasibility study is performed for searching vector-like leptons at a muon collider, in the context of the "4321 model", an ultraviolet-complete model with rich collider phenomenology together with potential to explain recent existing some B physics measurements or anomalies. In this paper, we perform a Monte Carlo study with various machine learning techniques, and examine the projected sensitivity on vector-like leptons over a wide mass range at a TeV-scale muon collider. We find that a 3 TeV muon collider with only 10/fb of data can already be sensitive to cover the mass range of a vector-like lepton up to 1450 GeV.Comment: CPC Published Versio

Wireless powered communication networks using peer harvesting

For an energy-constrained wireless network, energy harvesting (EH) is a promising technology to prolong the network life. Whether traditional near-field wireless power transfer (WPT) using inductive and resonant coupling or far-field WPT via radiated electromagnetic waves, both of them draw considerable research interests these years [1], [2]. In particular, the far-field WPT is meaningful for wireless powered communication (WPC) networks. A fundamental tradeoff was first studied for simultaneous wireless information and power transfer (SWIPT) in [3], [4]. These results aroused the interest of researchers. Subsequently, wireless communication with EH technology was presented in [5], [6]

1,4-Bis[3-chloro-2-(chloro­meth­yl)prop­yl]benzene

The title mol­ecule, C14H18Cl4, possesses a crystallographically imposed inversion centre, which coincides with the centre of benzene ring. In the absence of classical inter­molecular inter­actions, van der Waals forces help the mol­ecules to pack in the crystal

Tetraethyl 2,2′-(2,3,5,6-tetrafluoro-p-phenylenedimethylene)dipropanoate1

In the mol­ecule of the title compound, C22H26F4O8, a crystallographic inversion centre is located at the centroid of the benzene ring. C—H⋯F and C—H⋯O intra­molecular hydrogen bonds are observed as well as an inter­molecular C—H⋯O inter­action

2,2′-(p-Phenyl­enedimethyl­ene)bis­(propane-1,3-diol)

The mol­ecule of the title compound, C14H22O4, is centrosymmetric. In the crystal, the mol­ecules are linked through O—H⋯O hydrogen bonds into a three-dimensional network

Sulphur isotopes toward Sagittarius B2 extended envelope in the Galactic Center

The isotopic ratios are good tools for probing the stellar nucleosynthesis and chemical evolution. We performed high-sensitivity mapping observations of the J=7-6 rotational transitions of OCS, OC34S, O13CS, and OC33S toward the Galactic Center giant molecular cloud, Sagittarius B2 (Sgr B2) with IRAM 30m telescope. Positions with optically thin and uncontaminated lines are chosen to determine the sulfur isotope ratios. A 32S/34S ratio of 17.1\pm0.9 was derived with OCS and OC34S lines, while 34S/33S ratio of 6.8\pm1.9 was derived directly from integrated intensity ratio of OC34S and OC33S. With independent and accurate measurements of 32S/34S ratio, our results confirm the termination of the decreasing trend of 32S/34S ratios toward the Galactic Center, suggesting a drop in the production of massive stars at the Galactic centre.Comment: 20 pages, 7 figures, accepted by PAS