Tailoring energy transfer and transport mechanisms in metal oxide - metal nanoparticles heterostructures for enhanced light harvesting – TETROX

Metal oxides (MO) decorated with metal nanoparticles (NPs) have demonstrated an enormous applicative potential in domains such as chemical sensing, photovoltaics, visible light photodegradation, photocatalytic materials, photoelectrochemical water splitting or photodetectors. It is believed that the plasmonic resonance of the NPs enhances the interaction of the MO material with light due mainly to three mechanisms: light scattering, plasmon-induced resonant energy transfer (PIRET) and hot carrier injection However, the effect depends drastically on metal-oxide/metal NP coupling which is far from being understood in detail, although at the heart of all envisioned applications.

The TETROX project tackles the persistent challenge of inefficient light-to-energy conversion in metal oxide (MO) nanostructures, which are constrained by wide bandgaps and rapid electron-hole recombination. By strategically integrating plasmonic gold nanoparticles (Au NPs) with ZnO and CuO nanostructures via atomic layer deposition (ALD), this initiative aims to harness localized surface plasmon resonance (LSPR) effects to amplify light harvesting and charge transport.

The main objectives of TETROX are:
(i) to investigate the coupling mechanisms of metal-NP decorating archetypal n- and p-type metal oxide semiconductors (e.g. ZnO, CuO), including local electrical properties under light irradiation at various wavelength using original nanoscale spectroscopy measurements developed at IPCMS and simulations in LIST;
(ii) to investigate the influence of the coupling between metal NP and MO surface on the photocurrent, and in particular to disentangle the effects of direct charge transfer vs. resonant energy transfer, using ultra-thin dielectric deposition and local photoconductance spectroscopy;
(iii) to control the conformal deposition of metal NP on complex 3D oxide nanostructures using original conformal vapor-phase deposition methods developed in LIST for enhanced light harvesting.

Anticipated outcomes include a responsivity enhancement and extended photodetection range in Au-MO heterostructures compared to bare MOs. The integration of ALD with nanoscale spectroscopy and modeling will yield actionable design principles for 3D plasmonic systems, such as optimal NP density for maximal scattering or interfacial layer thickness for balanced energy/charge transfer. These insights will bridge fundamental knowledge gaps in plasmonic enhancement mechanisms while providing a scalable framework for next-generation optoelectronic devices, including high-efficiency solar cells, ultrasensitive photodetectors, and robust photocatalytic platforms.

TETROX directly addresses the criteria defined by axis H.10, including the controlled synthesis of functional nano-objects, the precise management of interface interactions and the demonstration of new properties resulting from nanoscale couplings. The project specifically addresses the challenges related to nanostructuring, functionalization and precise control of interfaces at the nanoscale. By combining atomic layer deposition (ALD) to obtain conformal and finely controlled gold metal nanoparticles (Au NPs) on complex metal oxide nanostructures, this project explores nanoscale interactions to generate new optoelectronic properties through plasmonic coupling.