## 3 Results and Discussion  
Figure 1(a) shows the normalized absorption spectra of Ag NPs and Ag NWs, together with the normalized absorption and PL spectra of Alq\({}_{3}\) (pure). The signature LSPR peak of Ag NPs is observed at 354 nm. Two LSPR peaks at 349 and 396 nm in the absorption spectra of Ag NWs are ascribed to the transverse quadrupole and transverse dipole resonance, respectively [27]. The overlap between the LSPR bands and absorption/PL spectra of Alq\({}_{3}\) is indicative of the possibility of resonance between the LSPs excited by Ag nanostructures and the absorption/PL of Alq\({}_{3}\). Normalized absorption spectra of Alq\({}_{3}\) (pure), Alq\({}_{3}\) (Ag NPs) and Alq\({}_{3}\) (Ag NWs) are shown in Figure 1(b). All the samples exhibit a main absorption peak at 391 nm and a shoulder at 336 nm, which are assigned to the \(\pi-\pi^{\star}\) electron transition [28]. However, Figure 1(a) exhibited that the PL spectra only meet the mirror image relationship with the main absorption band, indicating that there are some differences in the electronic transition between the main absorption band and the shoulder. Both of them have \(\pi-\pi^{\star}\) transitions localized on the 8-quinolinolato skeletons, but the main absorption peak also mixes an intramolecular charge transfer transition between the ligand and the metal [29]. The introduction of Ag nanostructures did not change the profile of the main peak, except for enhancing the absorption intensity. However, compared with the normalized main peak, the relative intensity of the shoulder seems to be weakened, indicating that the LSPR effect at the main absorption peak is stronger than that at the shoulder. As seen in the inset of Figure 1(b), the enhancement ratio of absorption is dependent on the wavelength, obvious enhancement occurs between about 360-430 nm, which is consistent with the two intersections between the LSPR band and the main absorption peak of Alq\({}_{3}\). Additionally, this result is consistent with the relatively weak LSPR effect at 336 nm in the shoulder mentioned above. The maximum enhancement ratios are 2.2 for Alq\({}_{3}\) (Ag NPs) and 1.1 for Alq\({}_{3}\) (Ag NWs). The absorption intensity of the former is twice that of the latter, indicating that the absorption enhancement is more derived from LSPs, because almost all SPs in Ag NPs belong to LSPs, while LSPs and PSPs coexist in Ag NWs. The Ag NWs can form a homogeneous network which increases the electric fields by scattering effects, excited LSPs on the surface and PSPs propagating along the Ag NWs/Alq\({}_{3}\) interface [30]. Figure 1: SEM images of the synthesized (**a**) Ag NPs and (**b**) Ag NWs. PL spectra of samples are shown in Figure 3a. The excitation wavelength at 405 nm is near the main absorption peak, thus ensuring efficient excitation of the samples. The spectral parameters obtained from absorption and PL spectra at room temperature are summarized in Table 1. It is observed that the PL peaks of all the samples are located at 529 nm. There was no peak shift, suggesting no chemical interaction between the Ag nanostructures and Alq\({}_{3}\). The spectral feature is almost unchanged except that the full-width at half maximum (FWHM) narrowed by 5 nm for Alq\({}_{3}\) (Ag NPs) and 10 nm for Alq\({}_{3}\) (Ag NWs), indicating strong coupling between the LSPR energy and the PL wavelength of intrachain excitons [31]. With the introduction of Ag NPs and Ag NWs, the integrated PL intensities (IPLI) exhibit enhancements of about 4 and 4.6 times (from 8.5 \(\times\) 10\({}^{4}\) to 3.4 \(\times\) 10\({}^{5}\) and 3.9 \(\times\) 10\({}^{5}\) a.u. ), respectively. Generally speaking, absorption enhancement and SPs-coupled emission are two main reasons for PL enhancement; the former can only influence the PL intensity, but the latter can both modulate the PL intensity and spectral shape [32].