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ARTICLE IN THE RENOWNED JOURNAL SCIENCE

New Applications for Semiconductor Quantum Dots

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Mapping application fields of semiconductor quantum dots. © García de Arquer et al., Science 373
Halbleiter-Quantenpunkte sind in vielfältigen Anwendungsfeldern nutzbar.
Our everyday life is shaped and enabled by semiconductors: They form the foundation for the electronics in computers and mobile phones, and they make significant contributions to optoelectronics through lasers and light-emitting diodes. The crucial factor for technical applications is the possibility to shrink the dimensionality of semiconductor devices, thereby restricting the free movement of charges – first from three dimensions to two, and then further to one and zero. In zero-dimensional structures, also known as quantum dots, electrons locked inside exhibit discrete energy levels, like electrons in atoms. For that reason, quantum dots are often called artificial atoms. In collaboration with international researchers, TU Dortmund University physicist and president Prof. Manfred Bayer has now demonstrated the potential for further applications of quantum dots.

The development of quantum dots began in the mid-1980s. Two different methods for fabricating them were established: one based on physics, carried out in a high vacuum (epitaxial quantum dots); and the other chemistry-based, through synthesis in suitable solutions (colloidal quantum dots). Both methods quickly found their way into applications: Epitaxial quantum dots are used, for example, in quantum dot lasers, colloidal quantum dots as "color converters" to generate the colors green and red in television screens. More recently, researchers have been making great strides, especially in the production of quantum dots, that make further applications possible.

Applications in photovoltaics and in the greenhouse

Prospects and problems associated with such applications are the subject of a recent journal article co-authored by experts from Toronto, Chicago, Los Alamos, Tokyo, Barcelona, and Dortmund. It was published in the leading scientific magazine Science. The authors discuss numerous possible application areas for such zero-dimensional structures.

For example, embedding colloidal quantum dots in windows could revolutionize photovoltaics. To make this possible, they need to be designed in such a way as to allow visible light to pass through, to keep indoor spaces as bright as ever. On the other hand, they have to absorb light in the infrared range so that it can then be converted into electrical energy. This can be achieved through the appropriate choice of material and the size of the quantum dots. In this way, for example, all the windows in the facades of high-rise buildings could be used for photovoltaics. Also, with this technology, the sunlight in greenhouses could be directed in a targeted manner so that crop plants can ripen and be harvested more quickly.

Portrait photo of Prof. Manfred Bayer © Benito Barajas​/​TU Dortmund
Prof. Manfred Bayer is a physicist and president of TU Dortmund University.