Fluorene compounds are a class of optoelectronic materials with rigid planar biphenyl structures. Fluorenone can be obtained by oxidizing the methylene group between two benzene rings in fluorene to carbonyl. Fluorene and fluorenone compounds have the advantages of wide band gap, high fluorescence efficiency, high stability, good charge transport ability and excellent processability. Fluorene and fluorenone compounds have always been an important semiconductor material in the optoelectronic information industry. Small molecule semiconductor materials have relatively few segment defects, have a certain relative molecular mass, and are easy to be purified and studied. Therefore, designing fluorene and fluorenone into small molecule semiconductor materials will improve the strength and life of semiconductor devices.
Figure 1. Chemical Structures of Fluorene and Fluorenone
- Organic Light Emitting Diode (OLED): Fluorenes and fluorenones have excellent blue light emission properties. And its luminescence properties can be tuned by introducing different substituents. Such luminescent materials have the advantages of high luminous efficiency, good carrier transport ability, simple synthesis and good thermal stability, and are widely used in the field of OLED devices as blue luminescent materials.
- Fluorescence sensor: The π-conjugated host of fluorene and fluorenone compounds is used as the host for emitting fluorescent signal, and the recognition group containing N, O, S and other atoms is connected to form a probe molecule. Through the specific response of the recognition group to a specific substrate, the structural change of the fluorene and fluorenone probes leads to the change of the fluorescent signal, and finally achieves the "probe" effect, which is used in the field of fluorescent sensors.
- Small molecule transport materials: The introduction of hole transport groups such as thiophene and triphenylamine into the molecular structure of fluorene and fluorenone can improve the carrier mobility of such materials and obtain thermodynamically stable hole transport materials.
- Kwanghee Cho, M. Rajeshkumar Reddy, Dongkyu Kim, Dongil Ho, Chaeyoung Yun, SungYong Seo, Choongik Kim. Synthesis and characterization of fluorene derivatives as organic semiconductors for organic field-effect transistor [J]. Mol. Cryst. Liq. Cryst., 2019, 690, 1, 56-66.