Nitrogen-doped graphene quantum dots: Optical properties modification and photovoltaic applications
Nitrogen-doped graphene quantum dots: Optical properties modification and photovoltaic applications
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DOI：
10.1007/s12274-019-2337-4
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发表时间：
2019-05-01
期刊：
影响因子：
9.9
通讯作者：
Naumov, Anton V.
中科院分区：
文献类型：
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作者：
Hasan, Md Tanvir;Gonzalez-Rodriguez, Roberto;Naumov, Anton V.
在这项工作中，我们利用自下而上的方法合成氮自掺杂石墨烯量子点（NGQDs）从一个单一的葡萄糖胺前体通过环保的微波辅助水热法。使用受控臭氧处理进一步改变所生产的NGQD的结构和光学性质。臭氧处理的NGQD（Oz-NGQD）的尺寸减小到5.5 nm，晶格结构和I-D/I-G拉曼比由于含氧官能团的引入/改变而发生明显变化，这通过傅里叶变换红外（FTIR）光谱仪检测到，并通过能量色散X射线光谱（EDX）进一步验证，显示氧原子的原子/重量百分比增加。沿着结构修饰，GQD经历紫外-可见（UV-vis）吸收的降低，伴随可见（长达16分钟处理）和近红外（NIR）（长达45分钟处理）荧光的逐渐增强。这允许微调NGQD的光学性质用于太阳能电池应用，从而产生受控的发射增加，而受控的发射淬灭通过蓝色激光或热处理实现。优化的Oz-NGQD被进一步用于形成太阳能电池的光活性层，其最大效率为2.64%，提供了比未处理的NGQD器件提高6倍的性能和填充因子/电流密度提高3倍的性能。这项研究提出了改变和优化可规模生产的NGQD光学特性的简单途径，以提高太阳能电池的光伏性能。
In this work, we utilize a bottom-up approach to synthesize nitrogen self-doped graphene quantum dots (NGQDs) from a single glucosamine precursor via an eco-friendly microwave-assisted hydrothermal method. Structural and optical properties of as-produced NGQDs are further modified using controlled ozone treatment. Ozone-treated NGQDs (Oz-NGQDs) are reduced in size to 5.5 nm with clear changes in the lattice structure and I-D/I-G Raman ratios due to the introduction/alteration of oxygen-containing functional groups detected by Fourier-transform infrared (FTIR) spectrometer and further verified by energy dispersive X-ray spectroscopy (EDX) showing increased atomic/weight percentage of oxygen atoms. Along with structural modifications, GQDs experience decrease in ultraviolet-visible (UV-vis) absorption coupled with progressive enhancement of visible (up to 16 min treatment) and near-infrared (NIR) (up to 45 min treatment) fluorescence. This allows fine-tuning optical properties of NGQDs for solar cell applications yielding controlled emission increase, while controlled emission quenching was achieved by either blue laser or thermal treatment. Optimized Oz-NGQDs were further used to form a photoactive layer of solar cells with a maximum efficiency of 2.64% providing a 6-fold enhancement over untreated NGQD devices and a 3-fold increase in fill factor/current density. This study suggests simple routes to alter and optimize optical properties of scalably produced NGQDs to boost the photovoltaic performance of solar cells.