In the field of semiconductor research, a major breakthrough has brought hope for the future development of electronics. A team of researchers from the University of Cambridge and the Eindhoven University of Technology has tackled decades-old challenges in the field of organic semiconductors, opening up new avenues for numerous technological advances.
Manipulating electrons in organic semiconductors has long been a complex and difficult task to overcome. However, this collaborative research has succeeded in the production of an innovative organic semiconductor that allows electrons to move in a spiral shape. This unique feature has the potential to improve the efficiency of OLED displays, especially in TV and smartphone screens, and is expected to power emerging computing technologies such as spintronics and quantum computing.
The semiconductor developed by the researchers is capable of emitting circularly polarized light, which carries information about the "chirality" of electrons. Most inorganic semiconductors, such as silicon, have a symmetrical internal structure in which electrons move in no particular direction. The inspiration for the new organic semiconductors comes from nature. In nature, many molecules have a chiral structure, just like human hands, chiral molecules mirror each other. Chirality plays a key role in biological processes such as DNA formation, but in the field of electronics, it can be difficult to harness and control.
Drawing inspiration from nature, researchers have successfully fabricated chiral semiconductors by using molecular design strategies to guide semiconductor molecules to stack to form an orderly right- or left-handed helix column. Their findings were published in the prestigious journal Science.
Figure:Power Next Generation Electronics
One of the most promising applications for chiral semiconductors is display technology. Current displays often have a lot of energy waste due to the problem of screen light filtering. The chiral semiconductors developed by the research team can reduce these losses by emitting light, making the screen brighter and more energy-efficient.
Professor Sir Richard Flender, co-leader of the study at the Cavendish Laboratory at the University of Cambridge, shared his insights: "When I first started working on organic semiconductors, many people were skeptical about their potential. But today, organic semiconductors dominate the field of display technology. Unlike rigid inorganic semiconductors, molecular materials offer unparalleled flexibility. It's like we have a set of LEGO bricks that can be combined in all shapes, not just standard rectangular bricks.”
This newly developed semiconductor is based on a material called triazaperylene (TAT). TAT is self-assembled into a spiral stacking structure, allowing electrons to spiral along its structure like screw lines.
Co-first author Marco Prouss from the Eindhoven University of Technology explains: "When excited by blue or ultraviolet light, the self-assembled TAT emits a bright, strongly circularly polarized green light. Previously, this effect was difficult to achieve in semiconductors. The structure of TAT not only allows electrons to move efficiently, but also affects their luminescence process.”
By improving OLED manufacturing techniques, researchers have been able to integrate TAT into practical circularly polarized OLED (CP-OLED). These devices have broken records in terms of efficiency, brightness, and polarization levels, making them the best in their class.
Ritupano Chowdhury, co-first author of the Cavendish Laboratory, also from the University of Cambridge, said: "We have basically redesigned the standard process for making OLEDs, similar to the ones used in smartphones, so that chiral structures can be embedded in a stable, amorphous matrix. This provides a practical way to fabricate circularly polarized LEDs, which has long been a coveted goal in the field.”
The research is the result of a decades-long collaboration between the Flender research team and the team of Prof. Bert Major at the Eindhoven University of Technology. Professor Major emphasized the significance of this achievement: "This is a real breakthrough in the field of chiral semiconductor development. By carefully designing the molecular structure, we have succeeded in linking the chirality of the structure to the movement of electrons, which has never been reached at such a high level before.”
Chiral semiconductors are a major advancement in organic semiconductors, which today support an industry worth more than $60 billion. In addition to display technology, this development also has important implications for quantum computing and spintronics. Spintronics is a field of study that uses the spin of electrons, i.e., the inherent angular momentum, to store and process information, promising faster and safer computing systems.
The research was funded in part by the European Union's Marie Curie Training Network and the European Research Council. Richard Flender is a Fellow of St John's College, Cambridge, and Ritapano Chowdhury is a member of Fitzwilliam College, Cambridge. This groundbreaking work laid the foundation for a new era in electronics, in which the manipulation of light and electrons could lead to transformative technological breakthroughs.
