The emerging field of plasmonics has yielded methods for guiding and localizing light at the nanoscale, well below the scale of the wavelength of light in free space. Now plasmonics researchers are turning their attention to photovoltaics, where design approaches based on plasmonics can be used to improve absorption in photovoltaic devices, permitting a considerable reduction in the physical thickness of solar photovoltaic absorber layers, and yielding new options for solar-cell design. In this review, we survey recent advances at the intersection of plasmonics and photovoltaics and offer an outlook on the future of solar cells based on these principles.

Plasmonics for improved photovoltaic devices

Nano-sized TiO 2 photocatalytic water-splitting technology has great potential for low-cost, environmentally friendly solar-hydrogen production to support the future hydrogen economy. Presently, the solar-to-hydrogen energy conversion efficiency is too low for the technology to be economically sound. The main barriers are the rapid recombination of photo-generated electron/hole pairs as well as backward reaction and the poor activation of TiO 2 by visible light. In response to these deficiencies, many investigators have been conducting research with an emphasis on effective remediation methods. Some investigators studied the effects of addition of sacrificial reagents and carbonate salts to prohibit rapid recombination of electron/hole pairs and backward reactions. Other research focused on the enhancement of photocatalysis by modification of TiO 2 by means of metal loading, metal ion doping, dye sensitization, composite semiconductor, anion doping and metal ion-implantation. This paper aims to review the up-to-date development of the above-mentioned technologies applied to TiO 2 photocatalytic hydrogen production. Based on the studies reported in the literature, metal ion-implantation and dye sensitization are very effective methods to extend the activating spectrum to the visible range. Therefore, they play an important role in the development of efficient photocatalytic hydrogen production.

A review and recent developments in photocatalytic water-splitting using TiO2 for hydrogen production

Recent advances in the exploitation of localized surface plasmons (charge density oscillations confined to metallic nanoparticles and nanostructures) in nanoscale optics and photonics, as well as in the construction of sensors and biosensors, are reviewed here. In particular, subsequent to brief surveys of the most-commonly used methods of preparation and arraying of materials with localized surface plasmon resonance (LSPR), and of the optical manifestations of LSPR, attention will be focused on the exploitation of metallic nanostructures as waveguides; as optical transmission, information storage, and nanophotonic devices; as switches; as resonant light scatterers (employed in the different near-field scanning optical microscopies); and finally as sensors and biosensors.

Exploitation of Localized Surface Plasmon Resonance

S. Pillai would like to acknowledge the UNSW Faculty
of Engineering Research Scholarship. K.R. Catchpole
acknowledges the support of an Australian Research Council fellowship.

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Surface plasmon enhanced silicon solar cells

A surface science perspective on TiO2 photocatalysis

A simple and effective method was demonstrated to tune surface plasmon resonance (SPR) wavelength of silver island films by introducing a dielectric medium to vary interisland dielectric constant. The medium, either overcoating or sandwiching the silver islands, can make a dramatic effect on the tunability. We had extended the SPR wavelength tunability of standard silver island film substrates from 432 to 482 nm to 506 to 1310 nm using two dielectric layering methods. A generalized Maxwell–Garnett theory was applied to interpret these results.

Wavelength tuning of surface plasmon resonance using dielectric layers on silver island films

Optimization of antireflection coating for VO2-based energy efficient window

Nickel oxide electrochromic thin films were prepared by reactive DC magnetron sputtering. The as-deposited optical property and electrochromic behavior strongly depended on the target operation mode and the substrate temperature. The sample sputtered with low oxygen flow rate, high power and substrate temperature of 200-300° C showed a wide transmittance modulation range, and the deposition rate was as high as 30 nm/min. Its integrated luminous transmittance could be controlled from 6.6 to 82.3%. X-ray diffraction measurements of this sample in a colored state and bleached state suggested that the boundary and surface of NiO microcrystallites played an important role in the electrochromic reaction of sputtered nickel oxide films.

https://iopscience.iop.org/article/10.1143/JJAP.34.2440/pdf

Nickel Oxide Electrochromic Thin Films Prepared by Reactive DC Magnetron Sputtering

Thickness dependence of optical properties of VO2 thin films epitaxially grown on sapphire (0001)

A novel window structure composed of VO2 thermochromic film with TiO2 antireflection (AR) coating was proposed. TiO2 was chosen as the best AR candidatefor reasons that it is an AR material superior to the reported SiO2, and that it is capable to make the window multifunctional with excellent photocatalytic properties. Optical calculation was done for the proposed structure, which predicts a strong enhancement in luminous transmittance (Tlum). A TiO2 (40 nm)/VO2 (50 nm) structure, optimized to a maximum integrated luminous transmittance by calculation, was formed on SiO2 glass by magnetron sputtering. A maximum increase in Tlum by 53% (from 32% to 49%) was experimentally obtained. The proposed window is the most advanced among the similarly reported in being multifunctional with automatic solar/heat control, ultraviolet stopping, and possibly a wide range of photocatalytic functions in addition to being highly luminous transmitting.

https://iopscience.iop.org/article/10.1143/JJAP.41.L278/pdf

Kazuki Yoshimura

Papers

Wavelength tuning of surface plasmon resonance using dielectric layers on silver island films

Optimization of antireflection coating for VO2-based energy efficient window

Nickel Oxide Electrochromic Thin Films Prepared by Reactive DC Magnetron Sputtering

Thickness dependence of optical properties of VO2 thin films epitaxially grown on sapphire (0001)

A VO2-Based multifunctional window with highly improved luminous transmittance