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- Physics and Astronomy Colloquia
- Irvine Lectures
- Photonics Seminar
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- Cond Mat Seminars
- Organic Semiconductor Centre
- Theoretical Physics Discussion Group
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- History of Mathematics
- RSC Award Lectures
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- Special Mini-Symposium - Structural Chemistry at Central Facilities
- Strong coupling seminars
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- ScotCHEM Polymer and Soft Materials Conference
Viewing archived talks in: Photonics Seminar
Speaker: Mr Bernd Ebenhoch (University of St Andrews)
Organic solar cells have great potential for cost-effective and large area electricity production, but their applicability is limited by the relatively low efficiency. In this talk I report investigations of novel materials and the underlying principles of organic solar cells. I will show that â‘ the charge carrier mobility of organic semiconductors in the active layer of polymer solar cells has a rather small influence on the power conversion efficiency. Cooling solar cells of the polymer:fullerene blend PTB7:PC71BM from room temperature to 77 K decreased the hole mobility by a factor of thousand but the device efficiency only halved. â‘¡Subphthalocyanine molecules, which are commonly used as electron donor materials in vacuum-deposited active layers of organic solar cells, can, by a slight structural modification, also be used as efficient electron acceptor materials in solution-deposited active layers. These acceptors offer, compared to standard fullerene acceptors, advantages of a stronger light absorption at the peak of the solar spectrum. â‘¢A low band-gap polymer donor material requires a careful selection of the acceptor material in order to achieve efficient charge separation and a maximum open circuit voltage. â‘£The use of a processing additive in the casting solution for the active layer of organic solar cells of PTB7:PC71BM strongly influences the morphology, which leads not only to an optimum of charge separation but also to optimal charge collection.
On: July 9, 2015 From: 13h00 To: 14h00View talk
Ultra-lightweight and Super-sensitive: Novel Biomedical Applications of Flexible Membrane Lasers and Biointegrated Microlasers
Speaker: Marcel Schubert (University of St Andrews)
Laser light has developed into an almost universal tool with numerous applications in medicine and the live sciences. However, interfacing laser sources with biological samples, including single cells, tissue and whole organisms remains a challenging task due to the rigid and bulky nature of commercial lasers. By imprinting distributed feedback structures into free standing, nanometer-thin polymer membranes, highly flexible and ultra-lightweight membrane lasers can be fabricated that are easily integrated onto skin and contact lenses. In another approach, microlasers are integrated into the cytoplasm of living cells. Here, their unique emission profile is used as optical barcodes to tag and track large numbers of cells. Furthermore, the direct contact between the lasers and the cellular environment renders these devices excellent optical sensors for in vivo applications.
On: February 26, 2019 From: 14h00 To: 15h00View talk
Speaker: Ross Gillanders (University of St Andrews)
Light-emitting organic semiconductors can be exploited to detect hazardous chemicals including explosives and pesticides. This talk will outline recent developments in improving specificity of these sensors using molecular imprinting, new trace chemical sampling methods, and discuss field considerations from experiences on a test mine field and from detonating explosives on a military base.
On: March 12, 2019 From: 13h00 To: 14h00View talk
Speaker: Sebastian Schulz (School of Physics and Astronomy)
Nonlinear effects hold great potential for a wide range of applications - all-optical signal processing, beam shaping and steering, optical computing, sensing, detection and general meteorology, to name a few. However, typically non-linear effects are weak; a typical non-linear index change is on the order of 0.01% or less and therefore they typically require high-power, short-pulse lasers, as well as long interaction length or resonant enhancement. Here, we show that a thin metasurface (50 nm total thickness), consisting of metal antennas on an epsilon-near-zero (ENZ) film, can produce a giant non-linear response with the refractive index change, Δn , exceeding 2 across a broad spectral range in the near-infrared wavelength region.
On: March 26, 2019 From: 13h00 To: 14h00View talk
Speaker: Frieder Koenig ()
I will give an overview of our activities in the area of artificial event horizons in optical fibers. If light encounters media flowing at superluminal speeds, particles are generated from the quantum vacuum. This is in analogy to the flow of spacetime around a gravitational black hole and therefore is predicted to emit Hawking radiation.
On: April 9, 2019 From: 13h00 To: 14h00View talk
Speaker: Isla Barnard (University of St Andrews)
Monte Carlo radiative transfer (MCRT) methods use localised scattering and absorption probabilities to describe the path of photon packets through a medium. MCRT methods are ideally suited to modelling a complex structure such as the skin. Using codes originally developed by Kenny Wood for astrophysical modelling, a successful collaboration was forged between the University of St Andrews and the Photobiology Unit at Ninewells. During this talk I will present an overview of the value MCRT methods provide in medicine, and will go into greater depth about my own research.
On: April 16, 2019 From: 13h00 To: 14h00View talk