Partikeldetektion in mikrofluidischen Systemen

Analysis of microparticles is an important tool in medicine, biology and chemistry. In order to address future application areas, new systems will be produced by printing technology. In this work new microfluidic particle detection systems which employ planar optics are developed and analyzed. Because the characteristic of these new systems differs greatly from established particle detection systems the signals and statistics are analyzed in depth

Partikeldetektion in mikrofluidischen Systemen

Die Analyse von Mikropartikeln hat in Medizin, Biologie und Chemie eine große Bedeutung. Neue Analysesysteme sollen per Drucktechnologie hergestellt werden. Unter diesem Hinblick werden in dieser Arbeit neuartige optische Partikeldetektionssysteme auf Basis von Mikrofluidik und planaren Optiken entwickelt und untersucht. Da sich die Funktionsweise von etablierten Partikeldetektionssystemen deutlich unterscheidet, erfolgt eine detaillierte Untersuchung der Signaleigenschaften und Fehlerstatistik

Illumination angle and layer thickness influence on the photo current generation in organic solar cells: A combined simulative and experimental study

In most future organic photovoltaic applications, such as fixed roof installations, facade or clothing integration, the solar cells will face the sun under varying angles. By a combined simulative and experimental study, we investigate the mutual interdependencies of the angle of light incidence, the absorber layer thickness and the photon harvesting efficiency within a typical organic photovoltaic device. For thin absorber layers, we find a steady decrease of the effective photocurrent towards increasing angles. For 90-140 nm thick absorber layers, however, we observe an effective photocurrent enhancement, exhibiting a maximum yield at angles of incidence of about 50°. Both effects mainly originate from the angle-dependent spatial broadening of the optical interference pattern inside the solar cell and a shift of the absorption maximum away from the metal electrode

Compensation for RC-effects in organic photodiodes with large sheet resistances

Abstract-Transient measurements on semiconductor devices are distorted by parasitic effects due to the geometric capacitance of the device and the impedance of the attached measurement circuit. Together they form an RC-circuit. Ideally, the transient decay of the pulse response generated by such an RC-circuit follows an exponential function. We investigate the differential equations of the case of an oblong rectangular photodiode with significant sheet resistance of one electrode. We find that under a specific illumination profile the ideal RC-decay can be obtained which is an useful result for RC-compensation in organic photodiodes

Coupled T‑Shaped Optical Antennas with Two Resonances Localized in a Common Nanogap

Resonant optical antennas with nanoscale gaps are of high interest due to their ability to enhance electric fields in localized subdiffraction-limited volumes. They are especially attractive for coupling with quantum emitters. One challenge for applications that exhibit a spectral shift is to fabricate nanoantennas that provide two distinct resonances at the excitation and emission frequency, respectively. We propose a coupled T-shaped nanoantenna structure that provides independently controllable resonances with a common electromagnetic hot spot in the antenna gap. We demonstrate the fabrication of such structures and investigate experimentally and theoretically their spatial, time-integrated spectral- and polarization-dependent electromagnetic field properties. The nanoantennas exhibit two resonances with unique spectral and polarization responses. The resonance wavelengths are independently tailored by varying the geometry of individual T-shaped antennas