UV-visible-near infrared photoabsorption and photodetection using close-packed metallic gold nanoparticle network

Abstract

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 ͑NPs͒ in the UV-VIS ͑visible͒-NIR ͑near infrared͒ 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.

Multifunctional Au-ZnO Plasmonic Nanostructures for Enhanced UV Photodetector and Room Temperature NO Sensing Devices

“…The filled d-band in Au below the Fermi level provides large number of electrons for inter-band transition under UV light illumination3435. Upon UV excitation, the d-band electrons of Au NPs are excited to the conduction band and transfer to ZnO side due to the presence of electric field at the metal-semiconductor junction formed between Au and ZnO, resulting in higher photoconductivity.…”

ZnO Film UV Photodetector with Enhanced Performance: Heterojunction with CdMoO4 Microplates and the Hot Electron Injection Effect of Au Nanoparticles

“…It is reported that metal nanostructures can create and inject hot electrons into coupled semiconductors, which have potential applications in solar fuel cells, photodetectors, photocatalysts, solid state lasers, etc . Recently, the novel properties of Au nanostructures have been explored for UV PDs with enhanced performance .…”

Plasmon‐Enhanced Photoluminescence and Photocatalysis Reactions in Metal‐Semiconductor Nanomaterials: UV‐Generated Hot Electron in Gold‐Zinc Oxide

“…Add to that, gold nanoparticles have a filled d‐level in their electronic configuration (Au 0 : 1 s 2 2 s 2 2p 6 3 s 2 3p 6 4 s 2 3d 10 4p 6 5 s 2 4d 10 5p 6 6 s 1 4f 14 5d 10 ). This filled d‐orbital below the Fermi level supports a big number of electrons for the interband transitions under UV excitation …”

“…This filled d-orbital below the Fermi level supports a big number of electrons for the interband transitions under UV excitation. [65,66] On this basis, under UV irradiation, the charges in the UV absorbing material (ZnONPs in our case) will acquire sufficient energy, allowing e À to cross the Schottky barrier formed after the contact between ZnONPs and AuNPs (due to the difference in their work functions as assessed before), to transfer into the next material. Therefore, there will occur a charge transfer (CT) from ZnONPs into the AuNPs in our hybrid samples, which in turns decreases the number of e À in the CB of the ZnONPs.…”