9-Aminofluorene is an organic compound featuring a fluorene core structure with an amino group substituted at the 9-position. It is a pale yellow to brown crystalline solid. This compound serves as a versatile and important building block in organic synthesis and materials science. Its primary and most significant application is in the field of organic electronics and materials chemistry. 9-Aminofluorene and its derivatives are key precursors for the synthesis of various functional organic materials, including hole-transporting materials (HTMs), organic light-emitting diodes (OLEDs), and organic semiconductors. The rigid, planar fluorene scaffold contributes to good charge transport properties, while the amino group provides a site for further functionalization to tune electronic and optical characteristics. As a synthetic intermediate, it is widely used in the preparation of more complex fluorene-based compounds, dyes, and ligands. It is also employed in research as a starting material for fluorescent probes and sensors.