Variation in the Optical Properties of Carbon Dots Fabricated by a Green and Facile Strategy for Solar-Blind UV Detection

作者：Yong Fang, Zhiwei Zhao, Zhengjin Weng, Mengru Zhu, Wei Lei, Zhuoya Zhu, Suhaidi Shafie, Mohd Nazim Mohtar · 发表于：The Journal of Physical Chemistry C · 年份：2022 · DOI：10.1021/acs.jpcc.1c10087 · 被引用次数：14 · 研究领域：Carbon and Quantum Dots Applications、Nanocluster Synthesis and Applications、Quantum Dots Synthesis And Properties

Despite the strong light absorption and high efficiency of multiple carrier generation and collection of carbon dots (CDs), little attention has been paid to the field of photodetection. Herein, CDs are synthesized through a green and facile strategy, which only uses graphite rods and distilled water. It is found that the oxygen content and the optical properties of CDs could be modulated by the voltage applied between the two graphite rods. A series of tests reveal that the excitation-independent blue photoluminescence (PL) emission of as-prepared CDs is related to the topological defects. And the oxygen-containing groups would bring new energy levels between the band gaps of CDs, which enhanced the excitation-dependent yellow-green PL emission and the absorption from the near-ultraviolet (UV) to the visible range. The CDs with fewer oxygen-containing groups show strong UV absorption and short cutoff wavelength, and they are utilized to fabricate solar-blind UV photodetectors. Tested under 254 nm UV illumination, the detectors exhibit a high photoresponsivity (1.14 mA/W) and highly characteristic wavelength-dependent response ( R 254 / R 365 = 115). This study provides a deeper understanding of the relationships between optical properties and the structure/composition of CDs. More importantly, the solution processability of CDs paves the way for future high-performance, low-cost solar-blind photodetectors.