Strain-Induced Luminescence in Quantum Dots.

Semiconductor nanocrystals, also known as quantum dots, possess the remarkable ability to absorb and re-emit light in specific colors. These nanometer-sized particles have gained significant importance in the field of display technology due to their low-cost fabrication, long-term stability, and wide range of available colors. As a result, they have greatly enhanced the image quality of various electronic devices such as TV-sets, tablets, and mobile phones. Moreover, quantum dots are now being explored for their potential applications in green energy, optical sensing, and bio-imaging, further expanding their exciting prospects.

The recent publication titled “Band structure engineering via piezoelectric fields in strained anisotropic CdSe/CdS nanocrystals” in the esteemed journal Nature Communications has added to the appeal of quantum dots. This publication showcased a groundbreaking approach to manipulate the light emission of these nanocrystals. An international team of scientists from the Italian Institute of Technology, the University Jaume I, the IBM research lab Zurich, and the University of Milano-Bicocca collaborated to demonstrate this innovative technique.

Traditionally, the color of light emitted by quantum dots is determined by their particle size, known as the quantum confinement effect. However, the new strategy introduced in this study relies on a completely different physical mechanism. By growing a thick shell around the quantum dots, researchers were able to induce a strain that created an electrical field within the dots. This internal electric field, resulting from the compression of the inner core, now plays a dominant role in determining the emission properties of the quantum dots.

Overall, this research opens up new possibilities for manipulating the light emission of quantum dots, paving the way for further advancements in display technology and other fields of application.

The outcome is a fresh generation of quantum dots that possess properties surpassing those achievable solely through quantum confinement. This not only expands the range of applications for the well-established CdSe/CdS material set but also for other materials. According to the researchers, “Our discoveries introduce a significant new level of flexibility in the advancement of technological devices based on quantum dots.” They further explain, “For instance, the time interval between light absorption and emission can be prolonged by over 100 times compared to traditional quantum dots, paving the way for optical memories and innovative smart pixel devices. Moreover, this novel material has the potential to create optical sensors that exhibit high sensitivity to the electrical field in the nanometer-scale environment.”

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