Semiconducting Materials

Semiconducting materials are a class of materials with semiconductor properties. The conductivity of semiconducting materials is between the conductor and the insulator, and the resistivity is in the range of about 1mΩ·cm～1GΩ·cm. Semiconductor materials can be used to make semiconductor devices and integrated circuits.

Applications:

Semiconducting materials are widely used in many fields such as electronic devices, photocatalysis and biomedicine due to their advantages of excellent performance and rich variety.

• Electronic devices: Semiconducting materials are widely used in the field of electronic devices. Aluminum nitride is an atomic crystal with an energy bandwidth of 6.2 eV, belonging to diamond nitride, hexagonal crystal system, the crystal structure type is wurtzite type, and the color is white or off-white. As a new type of semiconductor ceramic material, aluminum nitride has a series of excellent characteristics such as excellent insulation, thermal conductivity, high temperature corrosion resistance, and thermal expansion coefficient close to silicon. It is widely used in electronic components. Group IIIA nitride semiconductor materials have high breakdown field strength, thermal conductivity, saturated electron migration rate, and excellent radiation resistance. For example, the forbidden band width of GaN is much larger than that of Si and GaAs, the maximum operating temperature is higher than that of the first and second generation semiconductor materials, and the breakdown field strength and saturation thermal conductivity are also much larger than that of Si and GaAs, so it is very suitable for making high temperature resistance, anti-radiation and high-power devices. In addition, electrons and holes in group IIIA nitride semiconductor materials can radiate visible light. Using this property, Group IIIA nitride semiconductor materials can be made into light-emitting diodes (LEDs), such as ultraviolet, blue, green, and white diodes, etc., which can be used for lighting and have a wide range of applications in daily life.

Figure 1. Semiconductor light emitting diode

• Photocatalysis: The application of semiconducting materials in the field of photocatalysis is mainly used as a photocatalyst. Semiconductor photocatalysis technology is one of the effective methods to produce H₂. Semiconductor photocatalyst can use visible light of solar energy to catalyze the decomposition of water or alcohol to produce H₂. Compared with the traditional industrial H₂ production method, the conversion of solar energy into H₂ by semiconductor photocatalysis technology is a carbon-free and pollution-free process, and the reaction conditions are mild and the operation is simple. The semiconducting materials used in the field of photocatalytic H₂ production mainly include TiO₂, g-C₃N₄, CdS, ZnS, ZrO₂, Fe₂O₃, etc. In addition, semiconductor photocatalysts can also be used for other photocatalytic reactions. For example, semiconductor photocatalysts can be used to catalyze the reduction of carbon dioxide by solar visible light, while reducing the greenhouse effect and selectively converting them into combustible gases such as carbon monoxide and methane. Under solar lighting conditions, semiconductor photocatalysts can generate electrons and holes with higher activity, which can be used to degrade various pollutants.

Figure 2. DPP photosensitizer molecular structure

• Biomedical: In the past few decades of development, photodynamic therapy (PDT) has continuously demonstrated its outstanding therapeutic advantages and excellent therapeutic effects. In clinical practice, photodynamic therapy is used to treat superficial bladder cancer cells, early obstructive lung cancer, Barrest esophagus, head and neck cancer, and skin cancer. The basis of photodynamic therapy is photosensitizer. Pyrrolopyrrole diketone (DPP) organic semiconductor materials have the advantages of low toxicity to normal biological cells, light stability, high extinction coefficient, high ROS value, suitable hydrophilicity and lipophilicity, and can be used for photosensitization of photodynamic therapy agent. In addition, due to its excellent photoelectric properties, high molar absorption coefficient and fluorescence quantum yield, pyrrolopyrrole dione is used as a highly efficient organic semiconductor material in the biological field for the production of fluorescent probes and fluorescent microscopes.

Figure 3. Semiconductor microscope

Classification:

Depending on the chemical composition, semiconducting materials can be divided into elemental semiconductor materials, inorganic compound semiconductor materials, organic compound semiconductor materials, and amorphous semiconductor materials.

References:

1. Jesús Jiménez-López. (2019). "Hot electron injection into semiconducting polymers in polymer based-perovskite solar cells and their fate." Nanoscale 11, 23357–23365.
2. Yankai Zhou. (2018), "Nitrogen-embedded small-molecule semiconducting materials: Effect of chlorine atoms on their electrochemical, self-assembly, and carrier transport properties." Dyes and Pigments 163 615–622.
3. Rajangam Vinodh;. (2015), "Synthesis and characterization of semiconducting porous carbon for energy applications and CO₂ adsorption." Journal of Industrial and Engineering Chemistry 21, 273-281.