Hot Electron Excitation from Titanium Nitride Using Visible Light

Abstract

One major strategy that has been used to inject carriers into wide-band-gap materials involves exciting hot carriers from a nanostructured metal using low-energy photons. Here, we demonstrate that titanium nitride (a conductive ceramic) can be used as an alternative for photoexciting hot carriers. Planar samples that form titanium nitride/zinc oxide/titanium nitride trilayers are fabricated, and the generation of photocurrent using visible light is confirmed. The photocurrent obtained by using titanium nitride is much larger than that obtained by using gold in a similar structure. Our results will therefore facilitate the use of titanium nitride, which is robust and inexpensive, in harvesting the visible region of the solar spectrum in photovoltaics and photocatalysis.

Thermal effects – an alternative mechanism for plasmon-assisted photocatalysis

“…This is, in fact, the principle underlying the use of "hot" electrons for photo-detection -a photon is detected only if it has sufficient energy to cross the Schottky barrier and travel to the detector on the semiconductor side; otherwise, the contact is considered to be Ohmic, see e.g., Refs. [9,[50][51][52][53][54]. A similar mechanism ensures "hot" electron action in upconversion experiments [55,56].…”

TiN@TiO2Core–Shell Nanoparticles as Plasmon‐Enhanced Photosensitizers: The Role of Hot Electron Injection

“…[ 18,19 ] Hybrid structures comprised of TiN and semiconductors such as TiO 2 and ZnO have been shown to produce higher photocatalytic or photovoltaic enhancement relative to gold–semiconductor heterostructures due to hot electron injection, and have been proposed for applications in solar energy harvesting. [ 20,21 ] However, up to now, few studies have explored the potential of TiN–semiconductor structures in bio‐photonic applications. Considering the inertness of TiN and its plasmon resonance in the biological transparency window, TiN–semiconductor nanostructures with carefully designed geometry may serve as plasmon‐enhanced photosensitizers for a number of biomedical applications such as photothermal [ 22 ] and/or photodynamic therapy (PDT), the latter being used clinically to combat cancer and infectious diseases by the localized generation of 1 O 2 and other reactive oxygen species.…”

Comparison of the ultrafast hot electron dynamics of titanium nitride and gold for plasmonic applications

“…This has been of great use in photocatalysis and photovoltaics where these energetic electrons are transferred to an adjacent material on these ultrashort timescales. Titanium nitride has been used in such applications, where the intrinsic absorption properties were used to generate hot-carriers using visible light that were then extracted across an Ohmic junction 1 . In addition, colloidal TiN has also been used for solar water splitting with plasmonically-generated hot eletrons 2 .…”