Indoline is an aromatic heterocyclic organic compound with the formula C8H9N. It has a bicyclic structure, which is formed by fusing a six-membered benzene ring and a five-membered nitrogen-containing ring. The compound is based on an indole structure, but the 2-3 bonds are saturated with Chemicalbook. Indoline is used in the synthesis of derivatives of indoles, and indoline dyes are used as sensitizers for quasi-solid dye-sensitized solar cells, which have good photoelectric conversion performance. It is also an intermediate in medicine and plant growth regulators.