The past decade saw rapid development of two-dimensional (2D) layered materials. Being thin and flexible, 2D materials show unique properties as well as high-performance for a variety of electrical and optoelectronic applications. Despite ever-growing progresses on developing 2D materials based devices, there is great amount of room for improving device performance as well as seeking additional functionalities. For example, electrical contact serves as the bottleneck for electrical or optoelectronic devices based on 2D materials. A systematic solution, preferably in large scale, would greatly boost the applicability of 2D materials in various device structures. Talking about semiconductor devices, how to reduce dark current as well as boost device speed has been a major challenge facing photodetectors based on 2D transition metal dichalcogenides. In addition, in real-world applications, many photodetectors work in a more complicated physical principle. For example, image sensors work in a charge integration manner. Can those 2D high-performance photodetectors demonstrate this compatibility? Furthermore, can we further combine the high-performance of 2D optoelectronics with its integrability, to realize its sensitivity on various surfaces? In this thesis, I illustrate my efforts in solving or partially solving the above few questions, aiming to achieve advanced and integrated functionalities of 2D materials. Specifically, I have tried tackling the contact resistance issue by direct synthesis of mixed phase in-planar junctions in large scale. In addition, photodetectors based on III-VI InSe materials as well as its junction structures have been explored for improved photodetection performance. Furthermore, a novel device transfer technique has been developed, enabling the transfer of 2D sensors to a variety of surfaces for near-field sensing applications.