The chemistry behind your LCD flat-screen devices: how a scientist changed the world
In a laboratory at the University of Hull 50 years ago, a new chemical compound was created that would impact the world as much as any drug, fuel or material. The man responsible for this society-changing invention was George Gray — his new liquid crystal molecules (now known as 5CB) made liquid crystal displays (LCDs) viable and kickstarted the multibillion-dollar flat-screen industry.
The story begins back in 1967 when John Stonehouse, a Labour MP and minster for technology under Prime Minister Harold Wilson, established a group to develop a technology that had only just made its debut on Star Trek — a full colour flat-screen display.
Unfortunately for Stonehouse, his amazing foresight has since been overshadowed by his attempt (in 1974) to fake his own death to avoid punishment for multiple counts of fraud and forgery.
But before we get back to the colourful characters involved, let’s take a look at the science of LCDs.
Pixels and light
Liquid crystals are a state of matter that sits between liquids and solids. They flow like a liquid, while the molecules within them maintain some order relative to each other, like in a crystal. The long and thin molecules pack against one another in an ordered rectangular arrangement of rows.
Crucially, these liquid crystal structures can interact with light in interesting ways, and this is key to how they work within flat-screen displays. Each pixel within an LCD is comprised of a light source, usually a light-emitting diode (LED), and a thin layer of liquid crystals sandwiched between two filters that scientists describe as polarising.
The light emanating from a bulb, LED or the Sun is known as unpolarised, in the sense that it consists of waves travelling outwards in a variety of orientations. By analogy, imagine a group of schoolchildren all waving skipping ropes. Some will wave their ropes up and down and some side to side, and some at angles in between.
Polarising filters bring order to emanating light waves by only allowing waves with a particular orientation to pass. As well as in LCDs, you find them in some sunglasses, for example. If we return to…