Rotating, twisted light can drive next generation electronics

Researchers are taking on a decades-old challenge in the field of organic semiconductors, opening up new possibilities for the future of electronics. Researchers led by Cambridge University and Eindhoven Institute of Technology have created spiral patterns that can improve the efficiency of OLED displays on television and smartphone screens, or organic semiconductors that can improve the efficiency of next-generation computing technologies such as spitronics and quantum computing.

The semiconductors they develop emit circular polarized light. In other words, light conveys information about the “dominant hand” of electrons. The internal structure of most inorganic semiconductors, such as silicon, is symmetrical, meaning that electrons pass through them without a preferred direction.

However, essentially, molecules often have chiral (left or right-handed) structures. Like the human hand, chiral molecules are mirror images of each other. Chirality plays an important role in biological processes like DNA formation, but it is a difficult phenomenon to utilize electronic devices to control.

However, by using naturally inspired molecular design tricks, researchers were able to create chiral semiconductors by fine-tuning the stack of semiconductor molecules to form right-handed spiral columns. Their results have been reported in scientific journals.

One promising application of chiral semiconductors is display technology. Current displays often waste a considerable amount of energy due to the way the screen filters light. Chiral semiconductors developed by researchers naturally emit light in a way that can reduce these losses, making the screen brighter and more energy efficient.

“When I first started working with organic semiconductors, many people doubted their potential, but now they dominate display technology,” said Professor Richard Friend of Cavendish Institute in Cambridge.

“Unlike rigid inorganic semiconductors, molecular materials offer incredible flexibility. They allow you to design completely new structures like chiral LEDs. This is like working with any kind of Lego set you can imagine, not rectangular bricks.”

Semiconductors are based on a material called triazatoluxen (TAT), which self-assembles into a helical stack, and allow electrons to spiral along their structure, like threads from screws.

“When exposed to blue or ultraviolet light, self-assembled TAT emits bright green light with strong circular polarization, which has been difficult to achieve in semiconductors.” “The structure of TAT allows electrons to move efficiently while affecting the way light is emitted.”

By modifying the OLED manufacturing technology, the researchers successfully incorporated the TAT into a circulating polarized OLED (CP-OLED). These devices exhibit record efficiency, brightness and polarization levels, making them the best.

“We essentially remade the standard recipe for making OLEDs as you would find on smartphones, allowing us to trap chiral structures within a stable, non-crystallization matrix.” “This provides a practical way to create cyclic polarized LEDs, something that has been evading the field for a long time.”

This work is part of a decades-long collaboration between a group of friends and Professor Bert Majer of the Eindhoven Institute of Technology.

“This is a real breakthrough in making chiral semiconductors,” Major said. “By carefully designing the molecular structure, we have combined the chirality of the structure into the movement of the electrons, which has never been done at this level before.”

Chiral semiconductors represent a step forward in the world of organic semiconductors, and now supports more than $60 billion in industries.

Beyond displays, this development also affects quantum computing and spintronics. This is a field of research that stores and processes information using electron spin or inherent angular momentum, which could lead to faster, safer computing systems.