Pramanik Ashim, Biswas Subrata, Tiwary Chandra Sekhar, Sarkar Rajat, Kumbhakar Pathik
Nanoscience Laboratory, Department of Physics, National Institute of Technology Durgapur, Durgapur 713209, India.
Department of Material Science and Nano Engineering, Rice University, Houston, Texas 77005, United states.
ACS Omega. 2018 Nov 29;3(11):16260-16270. doi: 10.1021/acsomega.8b02473. eCollection 2018 Nov 30.
Luminescent downshifting (LDS) materials are in great demand for their applications in light conversion devices. In this work, by an ingenious chemical approach of in situ doping, N-doped graphene quantum dots (N-GQDs) have been synthesized with tailored green photoluminescence (PL) under ultraviolet (UV) light excitation. The incorporation of N atoms in the form of pyridinic and graphitic C-N bonding into the sp-hybridized graphitic framework of N-GQDs has led to tailored LDS via PL emissions. The LDS property of synthesized N-GQDs has been advantageously utilized to demonstrate enhanced responsivity () of a low-cost commercially available photoconductive cell (PC) for detection of UVA radiation through an indigenous technique. The linear optical responses of samples are optimized by varying the concentration and the dispersing medium. Also the N-GQDs are shown to be photostable in poly(vinyl alcohol) (PVA) hydrogel. A 60% enhancement in photocurrent of the PC-based photodetector under UV radiation has been obtained here by using N-GQDs/PVA as LDS material. Thus, detection of UVA radiation with a high specific detectivity (*) of 9 × 10 Jones and responsivity () of 3 A W has been demonstrated, which might open the opportunity of using this material in future energy conversion devices.
发光降频（LDS）材料因其在光转换器件中的应用而有巨大需求。在这项工作中，通过一种巧妙的原位掺杂化学方法，合成了在紫外（UV）光激发下具有定制绿色光致发光（PL）的N掺杂石墨烯量子点（N-GQDs）。以吡啶型和石墨型C-N键形式的N原子掺入N-GQDs的sp杂化石墨骨架中，通过PL发射实现了定制的LDS。合成的N-GQDs的LDS特性已被有利地用于通过一种本土技术证明低成本商用光电导电池（PC）对UVA辐射检测的增强响应率（）。通过改变浓度和分散介质来优化样品的线性光学响应。此外，N-GQDs在聚乙烯醇（PVA）水凝胶中显示出光稳定性。通过使用N-GQDs/PVA作为LDS材料，在此获得了基于PC的光电探测器在UV辐射下光电流60%的增强。因此，已经证明了具有9×10琼斯的高比探测率（*）和3 A W响应率（）的UVA辐射检测，这可能为在未来能量转换器件中使用这种材料提供机会。
