Transfer-Printed Optoelectronics for Cylindrical Concentrating Photovoltaics and Vascular Hemodynamics Monitoring

Abstract

The transfer printing method, which selectively separates optoelectronic elements based on compound semiconductor thin films epitaxially-grown on wafers and integrates them onto foreign substrates, offers applicability in various fields such as photovoltaic energy harvesting, wearable and implantable sensors. Optoelectronic elements transfer-printed onto flexible film substrates overcome the structural and functional limitations of conventional rigid elements, enabling applications such as curved surface-attached flexible solar cells, vertically stacking the light emitting diodes (LEDs), and the heterogeneous integration of photodetector and LEDs. The main focus of this dissertation is to design a system that meets the required performance through systematic analysis, and to fabricate devices by integrating optoelectronic elements using transfer printing method, demonstrate the applications in various fields, including concentrating photovoltaics (CPV) and hemodynamics monitoring. In this doctoral dissertation, a planar-type cylindrical CPV module design to save energy required for solar tracking and a vertically stacked LED structure for localized hemodynamics monitoring are proposed. Notably, red and blue-colored LEDs were vertically stacked on a foreign substrate using the transfer printing method, and a photodetector capable of measuring the light emitted from these LEDs was heterogeneously integrated on the same substrate, allowing it to function as a hemodynamic sensor. Thus, transfer-printed optoelectronics is a key technology that can expand the functionality of traditional semiconductors