A team of researchers at the University of Cambridge has made a significant breakthrough in the development of halide perovskites, a family of materials that could revolutionize solar cells, LEDs, and lasers. By creating a finely tuned “energy sandwich,” the researchers have achieved enhanced control over the atomic structure of these materials, paving the way for more efficient and durable devices.
Historically, perovskites have been recognized for their exceptional ability to absorb and emit light. They are also more cost-effective and capable of converting a broader spectrum of solar energy than traditional silicon materials. Despite this promise, the widespread application of perovskite devices has been hindered by issues related to stability and durability. Until now, precise control over the thickness of perovskite films and the interaction between different layers had presented significant challenges.
Breakthrough in Film Growth Techniques
The innovative research, detailed in the journal Science, introduces a vapor-based technique that allows for the growth of both three-dimensional and two-dimensional perovskites, layer by layer. This method enables researchers to control film thickness with exceptional precision, down to fractions of an atom. Such atomic-level control is crucial for developing functional, multi-layered structures needed for advanced electronic applications.
Professor Sam Stranks, co-lead of the research, emphasized the advantages of vapor processing over traditional solution processing, which can be inconsistent and difficult to control. “By switching to vapor processing—similar to methods used for standard semiconductors—we achieve a level of atomic control that is more reliable,” he stated.
The researchers employed a phenomenon known as epitaxial growth, allowing them to systematically build and observe the properties of perovskite stacks. They successfully varied each layer’s chemical composition, enabling targeted adjustments to the material’s light-emitting characteristics. Dr. Yang Lu, co-first author of the study, remarked, “It’s like constructing a semiconductor from the ground up, one atomic layer at a time, with materials that are more straightforward and cost-effective to process.”
Enhancing Charge Control and Device Efficiency
In addition to controlling the structural properties of perovskites, the team found ways to engineer the junctions between layers to influence the behavior of electrons and holes. This capability is vital for optimizing the efficiency of light emission in devices.
Professor Sir Richard Friend, another key contributor to the research, noted the team’s unprecedented level of tunability. “We can now determine whether charges remain together or are separated simply by adjusting the growth conditions,” he explained. The researchers discovered that they could manipulate the energy difference between layers by over half an electron volt, significantly extending the lifetime of electrons and holes to beyond 10 microseconds, far exceeding typical durations.
This advancement may lead to the creation of scalable, high-performance devices with applications ranging from lasers and detectors to next-generation quantum technologies. According to Professor Stranks, the ability to adjust the composition and performance of perovskites at will is a significant milestone that reflects the extensive investment in research at Cambridge.
The potential implications of this technology are profound, particularly for the manufacturing of inexpensive electronics and solar cells. As the team continues to refine their techniques, the prospect of integrating perovskites into commercial applications becomes increasingly plausible. This breakthrough not only highlights the versatility of halide perovskites but also signals a pivotal shift toward more sustainable energy solutions.
