Progress in research on p-type transparent conductive films based on related electronic materials
Recently, the Functional Materials Laboratory of the Institute of Solid Physics, Hefei Academy of Material Sciences, Chinese Academy of Sciences found in the study of p-type transparent conductive thin films based on related electronic materials: the adjustment of the electronic correlation strength in related oxides is to explore high-performance p-type TCO materials Effective Ways. Relevant research results were published in Physical Review Applied and were selected as editors' recommendation articles. Dr. Minglin Zhao from Jiangsu University of Science and Technology and He Gang from Anhui University participated in the research work.
Transparent conductive oxide (TCO for short) film is an important functional material that integrates optical transparency and conductivity. It has been widely used as a transparent electrode for optoelectronic devices such as flat panel displays, solar cells, touch screens, and light-emitting diodes. TCO materials are classified into an n-type, that is, an electron conductivity type, and a p-type, that is, a hole conductivity type according to the types of conductive carriers. The combination of n-type and p-type TCO thin films can also build devices such as transparent diodes and transparent field effect tubes, thereby greatly expanding the application field of TCO materials and creating new optoelectronic devices. However, the currently used TCO materials are all n-type, and the lack of high-performance p-type materials severely restricts the application of TCO materials. The reason is caused by the electronic structure of the metal oxide itself: the metal atoms and oxygen atoms in the metal oxide are ionically bonded, and the valence band is composed of strongly localized O 2p orbitals, resulting in the effective mass of the metal oxide holes Large, low hole mobility and poor hole doping. Therefore, how to adjust the price of the metal oxide to weaken its localization effect is the key factor to obtain a high-performance p-type TCO.
To this end, from the perspective of the electronic structure of the material, the researchers proposed the idea of ​​exploring the high-performance p-type TCO in the related oxide by using the electronic correlation caused by the Coulomb interaction between electrons: on the one hand, the electronic correlation will lead to The valence band is composed of d orbitals of transition metal ions or hybridized with O 2p orbitals, which ensures the p-type conductivity of the material; on the other hand, the increase in the effective mass of carriers caused by the electron correlation will be beneficial in the visible light region Open a transparent window. Therefore, electronic correlation can be used as a key parameter for exploring high-performance p-type TCO materials. Based on the above ideas, the researchers found that a good balance of p-type conductivity and optical transparency can be achieved in the V2O3 thin film with low electron correlation strength. V2O3 films with different thicknesses maintain high electrical conductivity (400-2122Scm-1) and have high transmittance in the visible region (40% -78%), with a transparent window of 0.97-3.6eV. The above results indicate that the adjustment of the electron correlation strength in the associated oxide is an effective way to explore high-performance p-type TCO materials.
This work was supported by the National Natural Science Foundation of China and key R & D projects of the Ministry of Science and Technology.
Comparison of the transparent conductive properties of typical p-type TCO films.
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