Researchers at the University of Cambridge have achieved significant advancements in the control of halide perovskites, a class of materials that could revolutionize solar energy, lighting, and quantum technologies. This breakthrough involves creating a finely tuned “energy sandwich” that enhances the efficiency and durability of these materials, which have long been regarded as a potential replacement for traditional silicon-based technologies.
Halide perovskites are known for their exceptional ability to absorb and emit light, making them appealing for applications in solar cells, light-emitting diodes (LEDs), and lasers. They are less expensive and more versatile than silicon, capable of converting a broader spectrum of solar energy into usable power. Despite their promise, the instability and short lifespan of perovskite devices have primarily limited their use to laboratory settings.
Breakthrough in Perovskite Film Growth
The research team, led by Professor Sam Stranks, has developed a new vapor-based technique to grow ultra-thin layers of perovskite films with atomic precision. This method allows for the alignment of atoms in the films, which can lead to the production of more robust and efficient devices. Their findings, published in the journal Science, suggest that it may soon be possible to manufacture functional perovskite devices at scale, similar to current semiconductor production processes.
The researchers employed a combination of three-dimensional and two-dimensional perovskites to create atomically-tuned stacks, utilizing a process known as epitaxial growth. This approach has enabled them to observe how light emission varies depending on the number of layers, whether single, double, or thicker.
“We aimed to grow a perfect perovskite crystal with variable chemical compositions at each layer, and we succeeded,” said Dr. Yang Lu, a co-first author of the study. “It’s akin to constructing a semiconductor layer by layer, but with materials that are easier and more cost-effective to process.”
Enhanced Control Over Charge Behavior
In addition to the structural advancements, the researchers discovered they could manipulate the junctions between layers to influence the interaction between electrons and holes—essential for the efficiency of light emission. Professor Sir Richard Friend, another co-leader of the research, stated, “We’ve achieved a level of tunability that was unexpected. We can now determine whether charges are kept together or separated by adjusting growth conditions.”
The team demonstrated the ability to fine-tune the energy difference between layers by over half an electron volt. They also found that they could extend the lifespan of electrons and holes to more than 10 microseconds, significantly longer than typical durations. This precision could lead to the development of high-performance devices designed for a variety of applications, including lasers, detectors, and next-generation quantum technologies.
The implications of this research could be transformative. “The ability to manipulate the composition and performance of perovskites at will reflects our extensive investment in this area at Cambridge,” Stranks said. “More importantly, it indicates that we can create operational semiconductors from perovskites, potentially revolutionizing the production of low-cost electronics and solar cells.”
As researchers continue to refine these techniques, the future of energy-efficient technology may look significantly different, driven by the capabilities of these innovative materials.
