Recent Advances in Carbon Doped ZnO Thin Films Correlating Structural Evolution with Optical Performance

Abstract

Carbon-doped zinc oxide (ZnO) thin films have garnered significant attention in recent years due to their ability to simultaneously modify the structural, electronic, and optical properties of zinc oxide. The introduction of carbon leads to the development of numerous defect configurations within the ZnO lattice, as well as significant changes in crystallinity, lattice stress, defect density, and electronic band structure. These modifications are crucial for enhancing the optical properties of ZnO thin films and for their application in high-tech optoelectronic devices. This review aims to provide a detailed account of the latest advancements in carbon-doped ZnO thin films and the relationship between structural changes and optical properties. It discusses different carbon insertion modes (substitutional and interstitial) and outlines the main techniques for film preparation. The review also provides a detailed analysis of the effects of carbon doping on crystal structure, crystal size, lattice parameters, microstress, and defect generation. Furthermore, the optical transmittance and absorption properties, optical bandgap geometry, refractive index, and absorption coefficient of the embedded carbon were investigated. A literature review revealed that carbon doping is an effective method for modifying the electronic structure of zinc oxide (ZnO) by introducing defective states and adjusting the bandgap, thereby enhancing visible light absorption and photovoltaic functions. These achievements have paved the way for the application of ZnO thin films in diverse fields, including photodetectors, solar cells, gas sensors, transparent electronics, and photocatalytic systems. Finally, some remaining challenges and future research directions were highlighted, emphasizing the importance of precise defect control, improved synthesis processes, and advanced characterization techniques for developing next-generation ZnO technologies.