P. Kang, B.G. Kim, S. Movaghgharnezhad, M. Kim
George Mason University,
United States
Keywords: 3D graphene, laser manufacturing, optical sensing, photodetector
Summary:
Graphene-based nanomaterials, known for their remarkable mechanical flexibility, high carrier mobility, broadband light absorption, and electrical conductivity, are ideal for photonics and optoelectronics applications, including photodetectors, light-emitting devices, solar cells, and wearable optoelectronic devices. Despite these advantages, monolayer graphene's low optical absorption (~2.3%) hinders its practical use in optoelectronics. Various methods, such as combining graphene with optical structures and creating vertical heterostructures, have been explored to enhance optical absorption. However, these approaches often involve complex and costly manufacturing processes, limiting their suitability for broadband photodetection. Developing a facile and cost-effective fabrication technique to enhance optical absorption and photoresponsivity in graphene-based photodetectors is highly desirable for practical applications. Porous silicon, known for improved optical absorption and highly sensitive photodetection, utilizes micro- and mesoporous structures to increase specific surface area, enhancing optical absorption and reducing light reflection and scattering. Similarly, 3D porous graphene (3DPG) created through transient laser photothermal processing offers mechanical flexibility, high electrical conductivity, and a large specific surface area. While laser-induced graphene has been explored for various applications, its micro- and nanoscopic structural effects on optical properties and photoresponse remain unexplored. We aim to fill this knowledge gap, providing insights into the micro-/nanostructural–optical properties of laser-induced graphene for improved understanding and potential advancements in photonic and optoelectronic applications. We present high-sensitivity photodetectors using 3D heterogeneous multiscale porous graphene structures fabricated through a laser photothermal method. The study examines the effects of sub-microsecond photothermal processing on the 3DPG structures and delves into the distinctive roles played by 3D graphene structures in enhancing optical and optoelectronic properties. Additionally, the study explores the optoelectronic performance of the 3DPG structures for designing high-sensitivity photodetector systems. Our approach to engineering the structures of 3DPG and enhancing its optical and optoelectronic properties via structural mechanisms is unique as we use chemically-modified polymer and submicrosecond transient photothermal processing. The potential of fPI-3DPG is demonstrated, showcasing its ability to function as a highly sensitive, flexible photodetector device with a broad visible-light photoresponse. 3DPG synthesized via the laser-based manufacturing approach is a novel optical functional material with a wide range of potential applications in optoelectronics and sensing. Moreover, the one-step synthesis and direct device fabrication process demonstrated in this study suggests that fPI-3DPG has the potential to be used in the development of multifunctional, high-sensitivity, and cost-effective wearable optical sensor devices.