Exploiting Luminescence Emissions of Solar Cells for Internet-of-Things Applications

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In this project, a new type of electronic device that uses light and solar cells to communicate wirelessly will be developed. An interesting fact about solar cells is that the same physical principle that allows solar cells to absorb photons also allows them to emit photons when excited by light or electricity. This phenomenon is known as luminescence. For most solar cells, this bidirectional process is not symmetric. That is, photon absorption is more efficient than photon emission. This is the case for silicon solar cells. There are other materials, however, such as Gallium Arsenide (GaAs) that are efficient at both absorbing and emitting photons. In this project the light emitted by GaAs solar cells will be modulated to transmit information wirelessly. Devices that use this approach will be able to use their solar cells as optical antennas that transmit and receive information optically while capturing energy from their environment to power themselves. The proposed technology will provide a new means of communication for devices connected to the Internet-of-Things (IoT). The IoT extends the Internet to everyday objects in a seamless manner with the goal of enhancing our lives. For instance, the proposed devices can be used in smart labels to monitor the temperature of perishable goods as they move through the supply chain. They can also be used in smart homes and smart factories to connect appliances and tools to the IoT. Other applications include environmental and agricultural monitoring. This project will advance the field of electronics and communications by providing a new class of wireless devices. This project will also enhance the education of American college and pre-college students by involving them in research activities to stimulate their interests in Science, Technology, Engineering, and Mathematics (STEM).The objective of this project is to take advantage of the luminescence emissions of GaAs solar cells to create a new type of wireless device that transmits information optically. Previously, photo-luminescence and electro-luminescence emissions were employed to characterize defects and materials parameters of solar cells. Here, luminescence emissions are exploited for wireless communications by modulating their intensities. Hence, this project has the potential to start a new area of research in optical communications in which light is used to convey energy and information to and from passive devices. Given that these devices will employ a new approach to the transmission of information, the project will address several fundamental questions and technical challenges to make the proposed concept viable. In particular, this project will address the following questions: 1) how fast and how far can information be transmitted using modulated luminescence emissions from high-efficiency solar cells 2) what is the best scheme for luminescence modulation 3) what circuit architectures and implementations will yield the lowest power consumption These questions will be studied and answered through the following research tasks: 1) characterizing solar cells as transmitters and receivers of information; 2) selecting suitable modulation schemes; 3) developing configurable hardware platform to validate selected luminescence modulation schemes; 4) developing a low-power platform to demonstrate self-powered operation of the proposed devices; 5) testing the hardware platforms. The proposed research will result in a new wireless technology for IoT applications. Advantages of this technology over radio-frequency wireless devices include reduced electromagnetic interference and avoidance of heavily-used and congested radio frequency spectrum. Other advantages include the ability of precise transmitter localization using camera-based receivers and the possibility to work underwater. As such, the proposed technology has the potential for creating new commercial applications and business opportunities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.