The surface stability of silicon nanowires (SiNWs) is crucial to their applications in nanodevices, such as transistors, sensors, photovoltaic cells, Li-ion batteries, etc. In this study, X-ray photoelectron spectroscopy (XPS) has been used to systematically investigate the stability of H-terminated surfaces of SiNWs at room temperature in aqueous solutions of different pH values. The hydrogen-terminated surfaces of SiNWs show relatively poor stability in aqueous solution, which depends on the solution pH. The oxygen in the solution had little effect on the oxidation of SiNW surfaces. With pH value increases in the solution, H-terminated SiNWs exhibit a greater extent of oxidation with higher oxidation rate. In low pH solution (<7), the surface species Si-OH can abundantly and stably exist and the oxidation process follows a multistep process, while, in high pH solution, the oxidation immediately happens by the assist of high concentration OHto form SiO 2 rapidly. The comparison of the stability of the SiNWs to that of silicon wafers is also discussed.

We investigate in this paper the influence of the localized plasmon resonance of gold nano-island structure on the photoluminescence of the exciplex in the polymer blends. The experimental results show that when the particle plasmon resonance overlaps the photoluminescence spectrum of the exciplex,the corresponding emission intensity is enhanced significantly. Furthermore, alonger lifetime is observed with the exciplex emission. We propose that the localized electrical field induced by the particle plasmon resonance increaseds the exciton diffusion length and thus conduces to the formation of the exciplex in the phase separation interface.

We investigate the influence of particle plasmon resonance of Au nanoislands structures on the exciplex emission in the polymer blend of poly (9, 9'-dioctylfluorene-co-benzothiadiazole) (F8BT) and poly (9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-l,4-phenylenediamine) (PFB). The experimental results indicate that when the particle plasmon resonance of the gold nanoisland structures overlaps the spectral range of the exciplex emission, significant enhancement of the photoluminescence can be observed. Furthermore, longer lifetime has been measured for the red-shift emission of the exciplex. We proposed that the localized field due to the particle plasmon resonance of the Au nanoislands has modulated the mechanisms for the formation of exciplex, which may be related to the exciton diffusion, charge transfer, and phase separation at the interface between the two materials.