## 3 Results and Discussion
The presence of Ag nanostructures dramatically changed the PL intensity and slightly modified the spectral profile so the PL enhancement should be attributed to the SPs coupled emission. Under excitation, the Ag nanostructures located near quinoline ligand in Alq\({}_{3}\) lead to local field enhancement around Alq\({}_{3}\) molecules, improving excitation efficiency and leading to the enhancement of PL [23]. The PL enhancement ratio is obtained by comparing the PL intensity of Alq\({}_{3}\) (Ag NPs) and Alq\({}_{3}\) (Ag NWs) with that of the Alq\({}_{3}\) (pure). As shown in Figure 3b, the nanostructure-embedded Alq\({}_{3}\) composites display the most significant PL enhancement at \(\sim\)520 nm, with the enhancement ratios reaching up to 4.5 and 5.3. The Ag NWs-incorporated Alq\({}_{3}\) exhibits a 430% enhancement, which is higher than its Ag NPs-incorporated counterpart (350%). The larger PL enhancement of Alq\({}_{3}\) (Ag NWs) is due to the enhanced scattering effect in the PSPs mode. The color coordinates of Alq\({}_{3}\) (pure), Alq\({}_{3}\) (Ag NPs) and Alq\({}_{3}\) (Ag NWs) in the International Commission on Illumination (CIE) are (0.344, 0.531), (0.346, 0.550) and (0.340, 0.554), respectively, as presented in Figure 4. The addition of Ag nanostructures mainly changed the \(y\) coordinates, which is indicative of a higher brightness induced by Ag nanostructures. Between the two nanostructure-embedded composites, Alq\({}_{3}\) (Ag NWs) displays the highest brightness. Through the color coordinates, correlated color temperatures are calculated to be 5280, 5271 and 5372 K, which are suitable for the manufacture of daylight fluorescents [33]. Figure 2: (**a**) Normalized absorption spectra of Ag nanostructures, and normalized absorption and PL spectra of Alq\({}_{3}\) (pure); (**b**) Normalized absorption spectra of Alq\({}_{3}\) (pure), Alq\({}_{3}\) (Ag NPs) and Alq\({}_{3}\) (Ag NWs); inset: the absorption enhancement ratio as a function of wavelength. Figure 4: CIE coordinates and color temperatures of Alq\({}_{3}\) (pure), Alq\({}_{3}\) (Ag NPs) and Alq\({}_{3}\) (Ag NWs). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & \(\lambda_{\textbf{abs}}\)**/**nm** & \(\lambda_{\textbf{PL}}\)**/**nm** & **FWHM/nm** \\ \hline Alq\({}_{3}\) (pure) & 336 & 391 & 529 & 112 \\ Alq\({}_{3}\) (Ag NPs) & 336 & 391 & 529 & 107 \\ Alq\({}_{3}\) (Ag NWs) & 336 & 391 & 529 & 102 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Spectral parameters obtained from absorption and PL spectra at room temperature. Figure 3: (**a**) PL spectra of Alq\({}_{3}\) (pure), Alq\({}_{3}\) (Ag NPs) and Alq\({}_{3}\) (Ag NWs); the bi-directional arrow lines represent the FWHM of samples; (**b**) PL enhancement ratio as a function of wavelength. In order to further explore the plasmon-exciton coupling affected by temperature, temperature-dependent PL spectra of samples in the range of 298-393 K are given in Figure 5. A decrease in PL spectra is observed with increasing temperature regardless of the absence or presence of Ag nanostructures, suggesting that at high temperatures, the electron-phonon interaction may restrain the emission from Alq\({}_{3}\), resulting in increased thermal non-radiative recombination and decreased PL intensity [31; 34]. Figure 6a shows the temperature dependence of the IPLI. The decrease of the IPLI with increasing temperature is owing to the increase of thermal disorder, which decreases electron delocalization [35]. When the strong plasmon-exciton coupling occurs at low temperatures from 298 to 323 K, the IPLI of nanostructure-embedded composites decreases faster than that of pure Alq\({}_{3}\), indicating a more effective thermal exchange process between the samples and the surrounding environment. The temperature dependence of IPLI can be fitted by the following equation [36]:  
\[I(T)=I_{0}/[1+C\exp(-E_{a}/k_{B}T)] \tag{1}\]  
where \(I_{0}\) is the IPLI at low temperature, \(E_{a}\) is the activation energy, and \(k_{B}\) is the Boltzmann constant.