We report electrostatically conjugated core- silica (SiO₂) shell upconversion nanoparticle (UCNPs@SiO₂), and gold nanorod (AuNR) nanocomposite (NC) combined with graphene to demonstrate > 200-fold UC fluorescence enhancement. Plasmonic AuNR and graphene, resulted in enhanced fluorescence in UCNP with a maximum for the SiO₂ shell thickness of 7 nm supported by finite difference time domain simulation of electric field distribution. In addition to the conventionally reported spectroscopic evidence, the plasmon aided UC fluorescence enhancement was demonstrated by direct confocal fluorescence imaging also, which was corroborated by a ~40% decrease in fluorescence lifetime. Finally, we have fabricated a NC/graphene hybrid photodetector (PD) that showed broadband (455–980 nm) photoresponse, with photoresponsivity of ~5000 AW⁻¹, and response times of 80–200 ms under 980 nm illumination. The multiphoton infrared (IR, ~980 nm) absorbing UCNPs also show interesting high energy (blue (B), green (G), and red (R)) photoresponse which is now conclusively attributed to one-photon absorption in the UCNPs. We report, probably for the first time, the performance of the hybrid PD under monochromatic and polychromatic illumination of B, G, R, B + G, B + R, G + R, and B + G + R, among others. The photocurrent under polychromatic conditions is dominated by the strongest monochromatic response, and does not scale with net power of the illumination. The loss in photocurrent is attributed to saturation in absorption, and photothermal heating. The fast response of the PD device has been demonstrated while detecting high frequency modulated AC remote controller signals, and attributed to the fast charge sweeping by the AuNRs.

我们报告静电共轭的核心二氧化硅（SiO ₂）壳上转换纳米粒子（UCNPs @ SiO ₂），和金纳米棒（AuNR）纳米复合材料（NC）与石墨烯结合，证明了> 200倍的UC荧光增强。等离子体AuNR和石墨烯导致UCNP中荧光增强，SiO ₂达到最大值电场分布的有限差分时域仿真支持7 nm的外壳厚度。除了常规报道的光谱证据外，还通过直接共聚焦荧光成像证明了等离激元辅助的UC荧光增强，这被荧光寿命降低了约40％所证实。最后，我们制造了一个NC /石墨烯混合光电探测器（PD），该探测器显示出宽带（455–980 nm）的光响应，光响应约为5000 AW ^-1，在980 nm的光照下响应时间为80–200 ms。吸收多光子红外线（IR，约980 nm）的UCNP也显示出令人感兴趣的高能量（蓝色（B），绿色（G）和红色（R））光响应，这些响应现在最终归因于UCNP中的单光子吸收。我们可能首次报告了混合PD在B，G，R，B + G，B + R，G + R和B + G + R等的单色和多色照明下的性能。多色条件下的光电流受最强的单色响应支配，并且不随照明的净功率成比例。光电流的损失归因于吸收饱和和光热加热。在检测高频调制的交流遥控器信号时，已经展示了PD设备的快速响应，