The two-dimensional (2D) materials have been widely developed recently in material characteristics with advanced optical and electrical properties, and they have been extensively studied as candidates for the next generation of optoelectronic devices. This review will mainly focus on the preparation methods and the light emitting applications of 2D transition metal dichalcogenides (TMDs), 2D black phosphorene (BP) and 2D perovskites. The review will first introduce the preparation methods for TMDs and BP. Due to the variations of band structure, exciton binding energies and light-matter interaction in TMDs and BP, the different light emitting devices (LEDs) designs based on TMDs and BP will be discussed and summarized. Then the review will turn the focus to 2D perovskites, starting with a description of the preparation methods for the different structural perovskites. In order to review and summarize the achievements of 2D perovskites-based LEDs, the high efficiency perovskites LEDs are discussed. Finally, the review will present challenges, opportunities, and outlook for the future development of 2D materials-based light emitting applications.

Nano-biotechnology research has become extremely important due to the possibilities in manipulation and characterization of biological molecules through nanodevices. Nanomaterials exhibit exciting electrical, optoelectronic, magnetic, mechanical and chemical properties that can be exploited to develop efficient biosensors or bio-probes. Those unique properties in nanomaterials can also be used in bioimaging and cancer therapeutics, where biomolecules influence the inherent properties in nanomaterials. Effective manipulation of nanomaterial properties can lead to many breakthroughs in nanotechnology applications. Nowadays, two-dimensional (2D) nanomaterials have emerged as viable materials for nanotechnology. Large cross-section area and functional availability of 2D or one-dimensional (1D) quantum limit in these nanomaterials allow greater flexibility and better nanodevice performance. 2D nanomaterials enable advanced bioelectronics to be more easily integrated due to their atomic thickness, biocompatibility, mechanical flexibility and conformity. Furthermore, with the development of 2D material heterostructures, enhanced material properties can be obtained which can directly influence bio-nanotechnology applications. This article firstly reviews the development of various types of 2D heterostructures in a wide variety of nano-biotechnology applications. Furthermore, future 2D heterostructure scopes in bioimaging, nanomedicine, bio-markers/therapy and bioelectronics are discussed. This paper can be an avenue for providing a wide scope for 2D van der Waals (vdWs) heterostructures in bio- and medical fields.