Publication date: 31st March 2013
Atomic layer deposition (ALD) is emerging as a technique for enhancing the performance and reliability of electrochemical energy devices such as photoelectrodes and dye-sensitized solar cells. Here we use electrochemical impedance and voltammetry methods to characterize the stability and water splitting performance of silicon cathodes coated with ultrathin (~1-10 nm) ALD-TiO2 films.
We examine silicon photocathodes fabricated from (111) wafers with ~0.5 cm2 functional area. Electrodes were tested in a standard three-electrode electrochemical cell in aqueous electrolyte. To ensure similar dopant profiles, experiments were run using a range of silicon samples from the same wafer. We discuss the effect of ALD film thickness and nucleation on open circuit and flat-band potential for Si PEC cathodes. The role of the TiO2 films on electrode performance and corrosion resistance are shown. Furthermore, the effect of Si surface preparation prior to TiO2 deposition is discussed as it relates to electrode performance and catalyst integration.
Mott-Schottky measurements indicate +20 mV shift in flat-band potential with every 1 nm of TiO2 deposited on the surface. Voltammetry under solar illumination shows that H+ reduction onset potential is dependent on TiO2 thickness, with thinner films (<5 nm) resulting in overpotentials similar to Si(111)/SiO2 surfaces. TiO2 films between 5 and 10 nm in thickness behave similarly to hydrogen-terminated Si(111) in terms of proton reduction overpotential, but better retain their performance under light and dark cycling (aging). We also show that good electrode performance is only achieved if the Si surface is H-terminated before ALD processing. If the native SiO2 is left intact, device performance suffers significantly due to the presence of the dielectric layer. A thin TiO2 layer also allows p-Si to function as a photocathode even with a continuous film of Pt, thereby eliminating Fermi level pinning observed with planar semiconductor/metal configurations.
Figure 1(A). Voltammograms are shown for p-Si(111) electrodes scanned under illumination. Bare p-Si electrode (solid lines) is tested immediately after hydrogen termination. ALD-coated (9 nm) electrode is tested as-is. Figure 1(B). Voltammograms for the same electrodes are shown after overnight ligh-dark cycling. The uncoated sample shows a greater degradation in performance than the TiO2-coated electrode.
nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.
Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.
International Conference on Hybrid and Organic Photovoltaics
International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.
Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.
The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.