'Organic' glass is in tech's future

It is nearly impossible not to view screens on a daily basis: Phones, tablets, smart watches — we can check social media, send texts, respond to email and watch YouTube videos from just about anywhere. Factor in TVs and desktop computers, and we are never far from looking at a screen.

A 2018 survey by Pew Research showed virtually all Americans — over 96% — currently own a cell phone. The percentage of those owning smartphones is a whopping 81%, up from the 35% they found in their first survey on the subject in 2011. The number of mobile users across the globe is now estimated at over 3.7 billion; more people worldwide own cell phones than toothbrushes. 

But is the next step for all that screen time to go organic?

Most people associate the term "organic" with food and food production, but soon it also may become attached to those screens we look at so frequently.

Organic light emitting diodes, more commonly known as OLEDs, are the latest technology to come from existing conventional LED technology. Semiconducting light sources from LEDs are created from electroluminescence: They produce photons by adding electrons to the holes within a device's emissive layer. The semiconductive layer allows electricity to enter and light to exit.

First developed by Eastman Kodak, OLED technology is the flat version of LED. OLED technology requires less energy and produces brighter light through thin, light-emitting films made of hydrocarbon chains, rather than the heavy metals that are found in semiconductors. This is the organic part of the technology.

Arizona State University investigator Ranko Richert, in partnership with two teams of collaborators at the University of Wisconsin, Madison, has received two separate funding grants from the National Science Foundation to investigate liquid crystals (LCs), glass and their molecular structure in materials related to modern technology and pharmaceuticals.  

“The project will create new materials that combine the advantages of both crystals and glasses — glassy materials with continuously variable molecular order,” said Richert, professor of chemistry and biochemistry in the School of Molecular Sciences.

LCs enable rapid adjustment of molecular organization by external control, making them useful for displays and sensors. Glasses merge liquid-like disorder and spatial uniformity with the mechanical strength of a solid, finding applications in optics, in electronics, and as amorphous pharmaceuticals.

Pharmaceuticals might not seem like an obvious application to glass and its properties, but it’s the behavior of the molecules within glass and the lack of long-range order of solid crystalline state that lend themselves to the development of potential new drugs.

Molecules in many drugs are uniformly arranged in a crystalline structure, limiting their bioavailability. In pharmaceuticals, if the molecules in the medications were an amorphous structure, where the molecules have a random arrangement, they would be more soluble. Not only would the rate of absorption improve, it could also extend the shelf life and storage of medications without crystallization.

The collaboration between Richert and Lian Yu, professor of pharmaceutical sciences and chemistry at the University of Wisconsin, Madison, will investigate new materials that combine the advantages of both LCs and glasses. Through their research, Yu and Richert expect to find new applications in organic electronics and optoelectronics. For example, the ability to control the organization of emitter molecules in the active layers of organic OLEDs, which are widely used in cell phone displays, can significantly enhance the efficiency of such displays. 

The second collaboration between Richert and Mark Ediger, professor of chemistry at the University of Wisconsin, Madison, will be using sophisticated analysis tools (ellipsometry, dielectric relaxation, calorimetry) to study glasses of organic molecules prepared by vapor deposition inside a vacuum chamber.

Glasses are common in everyday life with applications ranging from pharmaceuticals to engineering materials to cell phone displays. Even so, glasses have many properties that are not well understood. Studying glasses made of simple molecules as model systems will help to answer fundamental questions about glasses.

In this project, glasses are prepared directly from the vapor phase. This project investigates unusual molecular systems that have two distinct liquid states to understand how this is possible and how it might be used to produce new materials. A second goal is to understand how the method of preparing a glass can impact the mobility of molecules in the glass. There are advanced technologies such as quantum computing that can benefit from decreased mobility in glass.

The answers yielded from the team’s glass analysis will have the potential to understand glass behavior, help create new pharmaceuticals, and provide greener technology in screens that are used in a variety of applications.