## 1 Introduction  
In recent years, organic light-emitting diodes (OLEDs) have been attracting considerable attention because they exhibit excellent characteristics including self-luminescence, low power consumption and simple fabrication. Tris(8-hydroxyquinoline)aluminum (Alq\({}_{3}\)) has been widely used in OLEDs as an emitting layer material or electron-transport material owing to its excellent stability, high fluorescence quantum yield and large electron mobility [1, 2, 3, 4]. Therefore, the continuous performance optimization of Alq\({}_{3}\) materials is of great significance during the commercialization process of OLEDs.  
Nanostructures of noble metals, primarily gold and silver, have become the subject of interesting plasmon research [5, 6, 7]. Meanwhile, metal nanostructures have been employed in OLEDs for performance improvement due to their specific characteristics of surface plasmons (SPs) induced by free electron-photon interaction [8, 9, 10, 11, 12, 13]. Localized surface plasmons (LSPs) on the surface of metal nanostructures and propagating surface plasmons (PSPs) propagate along the surface of continuous metal both belong to SPs [14, 15]. A SPs-induced localized electric field could increase the radiative decay rate of the exciton, which means the electrons in the excited state have a greater probability to relax back to the ground state through the photoluminescence (PL) channel instead of a nonradiative phonon relaxation [16]. Meanwhile, when the absorption bands of SPs are closely matched with the excitation energy of light-emitting materials, the absorption energy of SPs could transfer to the materials, leading to a considerably enhanced PL intensity [17]. Therefore, the incorporation of metal nanostructures is an efficient strategy to enhance the PL performance of light-emitting materials in devices.  
Among various metal nanostructures, Ag nanowires (NWs) hold great potential due to their excellent optical and electronic, as well as high mechanical and physical stability [18]. The coexistence of LSPs and PSPs can be easily realized due to the morphology and reduced propagation losses of Ag NWs [19]. In our previous work [20], Ag NWs have been proven to improve the PL performance of conjugated polymers. However, due to the relatively small overlap between the localized surface plasmon resonance (LSPR) band and the PL spectra of polymers, the 190% PL enhancement is not sufficient to be satisfactory. If Ag NWs can be used to regulate materials with a greater degree of spectral overlap, a better regulatory effect will be achieved.  
Recent studies on the optical properties of Alq\({}_{3}\) regulated by Ag nanostructures have reported 1.2- to 4.4-fold PL enhancements [21; 22; 23; 24; 25]. Herein, we report the SPs-enhanced PL performance of Alq\({}_{3}\) decorated with Ag NPs and Ag NWs, respectively, and compare the effects of two nanostructures on the photophysical properties of Alq\({}_{3}\) in detail. A variety of spectral measurements including steady-state absorption and PL spectra, temperature-dependent, excitation intensity (EI)-dependent and detection angle-dependent PL spectra have been performed. We observe that the LSPR bands of Ag NPs and Ag NWs well match the absorption/PL spectra of Alq\({}_{3}\), resulting in a satisfactory improvement in optical properties. More notably, a 5.3-fold PL enhancement was achieved, which is higher than recent reports. Our research results will open up an effective route for the continuous optimization of luminous materials in OLEDs.