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Photocurrent generation and photodetection are usually based on semiconductor crystals including Si, CdS, and PbS. This work reports the enhanced photoabsorption and photodetection of close-packed metallic Au nanoparticles (NPs) in the UV-VIS (visible)-NIR (near infrared) region. Photoabsorption in the UV-VIS regions is associated with the interband transition and surface plasmon resonance of AuNPs, while the enhanced NIR absorption is due to the collective effect of interacting AuNPs in the close-packed network. Consequently, the AuNPs exhibits photodetection behavior in the wavelength range of 300–1500 nm. It is proposed that the inter-AuNP photoejection and delocalization of electron-hole pairs changes the carrier lifetime and transit dynamics in favor of photocarrier conduction, thus significantly facilitating photocurrent generation in the metallic AuNP close-pack. Moreover, due to the power-law conduction mechanism in AuNP networks, the quantum yield of AuNPs can be tuned from 10-6 to 10-1 photoelectron/photon by increasing the bias voltage from 0 to 5 V. The AuNP quantum yield of 10-1 at 5 V is as high as that of commercial Si photodetectors at 0 V, and this demonstrates the immediate applicability of AuNPs in photodetection. In view of the compatibility of AuNPs with wet-chemistry and inkjet printing processes at low temperatures, metallic AuNPs may provide a convenient alternative to semiconductor crystals in photodetection and perhaps photovoltaic applications. [ABSTRACT FROM AUTHOR]

The enhanced photoabsorption and photodetection of close-packed metallic Au nanoparticles (NPs) is described in the ultraviolet visible (UV-vis)-near infrared (NIR) region. The compatibility of AuNPs with wet-chemistry and inkjet printing processes at low temperatures has shown that metallic AuNPs have provided an alternative to semiconductor crystals in photodetection and photovoltaic applications.

We report exceptional optical limiting properties of two kinds of Ag nanoprisms (pure Ag nanoprisms and Au@Ag core-shell nanoprisms) in solution that were photochemically prepared. Fluence-dependent transmittance measurements using 7 ns laser pulses of 532 nm wavelength showed that the optical limiting properties of two kinds of silver nanoprisms in solution are slightly better than that of carbon nanotube suspensions, which is known as a benchmark optical limiter. Nonlinear scattering experiments suggested that nonlinear scattering should play an important role in the observed optical limiting effects. [ABSTRACT FROM AUTHOR]