摘要：
The strong, broad and tunable fluorescence emission of graphene oxide (GO) has shown the exciting optical ap-plications in many areas, such as fluorescence imaging in living cell, high sensitive detection of heavy metal ions, and the fabrication of optoelectronic devices. However, the intrinsic heterogeneous fluorescence intensity resulting from the variability in the power density of excitation laser and the non-uniform thickness of GO film, hinders its further appli-cations in the micropatterning, information storage and display technology, which requires homogeneous fluorescence emission. In contrast to the fluorescence intensity, the fluorescence lifetime of GO is determined by the intrinsic nature of chromophores, rather than the film thickness or excitation power density. Here we report that the fluorescence life-time is homogeneous for GO film, which eliminates the anisotropic optical properties of GO film. By reducing the GO film through the irradiation from a 405 nm continuous-wave laser at a certain power density on a home-built scanning confocal microscope, we find that the lifetime can be precisely modulated by controlling the duration of laser irradia-tion. It is determined that the lifetime gradually decreases with the increase of duration. As reported in the previous researches, the GO fluorescence originates from the graphene-like confined sp2 clusters and sp3 domains consisting of oxygen-containing functional groups, where the lifetime of sp3 domain is about 1.4 ns, and that of sp2 domain is 0.14 ns. During the photoreduction, the long-lived sp3 domains will decrease or convert into short-lived sp2 domains, resulting in the decrease of lifetime. Hence, by controlling the reduction degree or the ratio of the two domains, the lifetime of GO film can be determined. More importantly, the lifetime distributions of the reduction areas are very narrow, leading to a relatively homogenous background. The precise manipulation of lifetime can be used to fabricate micropatterns with high contrast. Combining with laser direct writing with features of maskless, facile processing ability and high spatial resolution, many versatile micropatterns, such as quick response code, barcode, graphic, alphabet, and numbers can be readily created based on the modulation of fluorescence lifetime. By using three optimized durations of laser irradiation, three distributions with narrow widths are obtained. Based on this processing, the micropatterns with three colors are determined, which indicates that the multimode optical recording can be created on the GO film based on the modulation of fluorescence lifetime. Furthermore, the multilayer micropatterns are also created. The robust and versatile micropatterns with film-thickness and excitation-power-independent features show their promising applications in electronics, photonics, display technology and information storage.%氧化石墨烯因其宽带可调谐的荧光发射特性已被广泛应用于荧光成像、金属离子高灵敏检测和光电器件的制备.相比于荧光强度,氧化石墨烯荧光寿命不受材料厚度和激发功率的影响,具有更为稳定和均一的特性.本文研究了在激光还原过程中氧化石墨烯荧光寿命逐渐减小的变化行为,发现了长寿命sp3杂化结构向短寿命sp2杂化结构的转变.通过精确控制还原时间,结合激光直写技术,在单层氧化石墨烯薄膜上实现了二维码、条形码、图形和数字等微纳图形的制备,还在多层氧化石墨烯薄膜结构上获得了多寿命多层微纳图形.这种微纳图形的制备具有灵活无掩膜、高对比和多模式的特点,可用于高密度光学存储、信息显示和光电器件制备等诸多领域.
