Polymer/macromolecule semiconductor building blocks usually have a long conjugated backbone, and their electrons are highly delocalized, which is conducive to charge transport. The intrinsic conductivity of this type of material is not large, but after oxidation or doping, the conductivity can be significantly improved, showing the properties of a conductor or a semiconductor. The band gap of polymer/macromolecular semiconductors is equivalent to that of inorganic semiconductors. Many conjugated polymer main chains can visually extend the chromophore, showing photophysical properties similar to dyes, such as photoluminescence, photoconductivity, and nonlinear optics. Polymer/macromolecule semiconductor building blocks can be used to make light-emitting diodes, field effect transistors and other devices. The preparation process is simple, inexpensive, easy to form large junctions, and is convenient for molecular design, so it has been widely used.
Figure 1. Polymer/macromolecule thin film transistor device structure
- Electroluminescent display device: Polymer/macromolecule semiconductors used in electroluminescence have the following characteristics: (1) Large-area thin films can be made by spin coating, casting and other methods; (2) Most conjugated polymers have excellent stability; (3) The electronic structure and light-emitting color of the conjugated polymer can be adjusted by changing and modifying the chemical structure; (4) It can be made into a very thin film (10-100nm) to generate the current density required for the device to emit light under a low driving voltage, thereby eliminating structural instability caused by doping. Electroluminescent devices made of polymer/macromolecule semiconductor materials have the advantages of low driving voltage, high luminous efficiency, emitting different colors of fluorescence, fast response speed (microsecond level), and luminous intensity proportional to current.
- Thin film transistors: The most important component in a transistor is the organic thin film semiconductor layer. Compared with small organic molecules, organic polymer films can be prepared by a simple solution method without complicated experimental techniques and equipment, and can also obtain higher carrier mobility, and are suitable for making flexible devices. Transistors prepared by polymer/macromolecule films have significant applications in fields such as flexible labels, flexible displays, and flexible electronic circuits.
- Fluorescence sensor: Organic semiconducting polymers/macromolecules are a kind of polymer materials with semiconducting properties due to conjugated electrons, which have been widely used in optoelectronic devices. Polymer/macromolecule semiconductors have the characteristics of large optical absorption cross-section, high fluorescence quantum efficiency, and fast radiation transition rate. These excellent optical properties are particularly suitable as fluorescence sensors for biological applications, such as fluorescence imaging, biosensing, drug delivery, and disease diagnosis and treatment.
- Yu Jin Jang, Eunah Kim, Seonghyeon Ahn, Kyungwha Chung, Jihyeon Kim, Heejun Kim, Huan Wang, Jiseok Lee, Dong-Wook Kim, Dong Ha Kim. Upconversion-Triggered Charge Separation in Polymer Semiconductors [J]. J. Phys. Chem. Lett. 2017, 8, 2, 364–369.