9H-Fluorene-1-carboxylic acid is a carboxylic acid derivative of the fluorene scaffold. It is a white to off-white crystalline powder with a molecular formula of C14H10O2. The molecule features a rigid, planar fluorene core substituted with a carboxylic acid group at the 1-position, which serves as a versatile functional handle for further chemical modifications. This compound is primarily utilized as a key synthetic intermediate in the preparation of advanced organic electronic materials. Its main application lies in the synthesis of fluorene-based polymers and small molecules for organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), and other optoelectronic devices. The carboxylic acid group allows for the construction of conjugated systems through esterification, amidation, or polymerization reactions, enabling the fine-tuning of electronic properties such as band gap, charge transport, and luminescence. As a functionalized fluorene derivative, it is also employed in organic synthesis as a building block for creating more complex polycyclic aromatic hydrocarbons (PAHs) and π-conjugated systems used in materials science research.