3D Radial Junctions for Robust and Flexible Optoelectronics

Marrying nanostructures with thin films is a recent trend in flexible optoelectronics to improve light trapping and mechanical stability. Radial junction (RJ) a-Si:H thin film optoelectronics, directly deposited upon the vapor-liquid-solid (VLS) grown silicon nanowires (SiNWs), can pave the way to achieving excellent flexibility and a high power-to-weight ratio (PTWR). Thanks to their vertical-standing geometry, SiNWs framework can enhance the mechanical stability of RJ units, by keeping the working region far away from the stress-rich substrate surface. Using low-melting-point metals as catalysts, the SiNW array can be fabricated at a low temperature down to 350 degrees C in a PECVD system, making it possible to directly construct robust RJ units on flexible, low-cost substrates, such as Al foil. In this review, the recent progress of the flexible RJ a-Si:H thin film solar cells/photodetectors that are directly fabricated on the surface of low-cost flexible substrates is reviewed. Moreover, these RJ flexible optoelectronics are demonstrated for use in wearable and real-time health monitoring, and as cardiac pacemakers for heart stimulation. This RJ technology highlights a promising potential to establish high-performance, low-cost, mechanically stable flexible optoelectronic for wearable, portable applications. This paper aims to review recent progress in the flexible radial junction a-Si:H thin film solar cells/photodetectors and their bio-applications. Radial junction a-Si:H thin film optoelectronic devices that are directly fabricated upon the low-temperature VLS-grown silicon nanowires can pave a promising way to boosting excellent flexibility and high power-to-weight ratio for lightweight, wearable, and portable applications.image