▎ 摘　　要

NOVELTY - A hybrid carbon nanosheet comprises graphene oxide nanosheet and carbon nanoring formed on graphene oxide sheet. USE - Hybrid carbon nanosheet used in optoelectronic devices (claimed), biological labels and sensors. ADVANTAGE - The carbon nanosheet provides optoelectronic device having excellent optical properties and optical stability. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) preparation of hybrid carbon nanosheet, which involves hydrothermally carbonizing low molecular weight precursor in the presence of a graphene nanocrystal; (2) usage of hybrid carbon nanosheet in optoelectronic device; and (3) light emitting method of hybrid carbon nanosheets, which involves (1) adding hybrid carbon nanosheet to solvent (A) to prepare a solution (A), and irradiating the solution (A) with excitation light to emit color (A), preparing a solution (B) by replacing solvent (A) of solution (A) with solvent (B) and irradiating solution (B) with excitation light to emit a color (B), preparing a solution (C) by replacing the solvent (B) of solution (B) with solvent (A), and irradiating the solution (C) with excitation light to emit a color (C).