10:40 — Steven Young
Boyajian’s Star: The Mysterious Dipper
Topic(s): Physics, Astronomy and ExoplanetsBoyajian’s star has captured the public’s imagination and the intrigue of scientists since its odd behaviour was first observed six years ago. Its bizarre light curve suggests that something obscures the star, changing the amount of light we receive day by day, often blocking out as much as a fifth of the star’s total output. Many theories have been espoused as to the cause of these dips: from artificial alien megastructures to interstellar dust. In this talk, I will give some background to this mystery and present my work on the topic, which asks: is it feasible that what we’re seeing is the passage of a family of exocomets that have been thrown in close to their host star by a nearby stellar companion?
10:55 — William Wood
Polymer Semiconductors (AKA “Bendy Conducty Things”)
Semiconductors form the bedrock of modern digital technology. Being materials that can be switched from electrically insulating to conducting and back again at high speed, they are extensively used for controlling the flow of current and balance of voltages throughout various types of circuits. As a result, they are an indispensable technology for creating logic circuits – from simple calculators to supercomputers – as well as amplifiers, photovoltaics (solar panels), light-emitting diodes (LEDs), and digital displays.
The materials traditionally used as semiconductors are typically well-ordered materials such as crystalline silicon, comprising atoms covalently bonded together in a regular grid. These materials offer high efficiencies, are widely used and understood, and are often referred to as being “inorganic”. However, in more recent years focus has grown on so-called “organic” semiconductors. These are – without trying to offend any chemists reading this too much – carbon-based materials, made of lattices of molecules instead of single atoms.
These tend to be significantly less efficient but offer more desirable physical properties. For instance, many of them are soluble, allowing for them to be “printed” onto a substrate much like how a printer patterns ink onto a page – enabling low-cost, large-scale manufacturing not otherwise possible. An example application that has already become mainstream is OLED displays – commonly found on smartphones and some newer televisions.
My research focuses on figuring out how charges move through a sub-group of these materials, known as polymer semiconductors, which offer the added bonus of being flexible. If you have ever looked at a television and thought, “I really wish I could bend that into an arbitrary shape”, then these might just be the materials for you. This talk will focus on how semiconductors work – in general, and specifically polymers – and the journey that has been my (completed) PhD and results therein.