National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China.
Sci Rep. 2013;3:2315. doi: 10.1038/srep02315.
We report a method to promote photoluminescence emission in graphene materials by enhancing carrier scattering instead of directly modifying band structure in multilayer reduced graphene oxide (rGO) nanospheres. We intentionally curl graphene layers to form nanospheres by reducing graphene oxide with spherical polymer templates to manipulate the carrier scattering. These nanospheres produce hot-carrier luminescence with more than ten-fold improvement of emission efficiency as compared to planar nanosheets. With increasing excitation power, hot-carrier luminescence from nanospheres exhibits abnormal spectral redshift with dynamic feature associated to the strengthened electron-phonon coupling. These experimental results can be well understood by considering the screened Coulomb interactions. With increasing carrier density, the reduced screening effect promotes carrier scattering which enhances hot-carrier emission from such multilayer rGO nanospheres. This carrier-scattering scenario is further confirmed by pump-probe measurements.
我们报告了一种通过增强载流子散射而不是直接修改多层还原氧化石墨烯（rGO）纳米球的能带结构来提高石墨烯材料光致发光发射的方法。我们通过使用球形聚合物模板还原氧化石墨烯来有意卷曲石墨烯层以形成纳米球，从而操纵载流子散射。与平面纳米片相比，这些纳米球产生的热载流子发光的发射效率提高了十倍以上。随着激发功率的增加，纳米球的热载流子发光表现出异常的光谱红移，其动态特征与增强的电子-声子耦合有关。考虑到屏蔽库仑相互作用，可以很好地理解这些实验结果。随着载流子密度的增加，减少的屏蔽效应促进了载流子散射，从而增强了来自这种多层 rGO 纳米球的热载流子发射。通过泵浦-探测测量进一步证实了这种载流子散射情况。
