Solar Fuels

Project 1: Perovskite-Silicon Tandem PEC Device with Atomically Engineered Interfaces 

PI: Prof. Vincent Tung, Prof. Stefaan De Wolf

Photoelectrochemical (PEC) process holds tantalizing prospect for producing solar fuels and value-added chemical commodity from economically viable and earth abundant resources such as water and CO2 using renewable solar energy. In this project, we propose a transformative concept to marry highly efficient perovskite-silicon (PVSK-Si) photovoltaics tandem as a photo-absorber with atomically thin, single-crystal 2D transition metal dichalcogenides (TMD) as an electrocatalyst to develop a hybrid PEC device. Here, PVSK-Si monolithic tandem photovoltaic device where Si heterojunction, SHJ, bottom cells are in connection with PVSK top cells) with a certified power conversion efficiency >25% will be functioned as a photoelectrode. Meanwhile, 2D TMD with a continuous single crystallinity over the wafer-scale and a tunable bandgap will be transferred on to the PVSK-Si monolithic tandem device as an electrocatalyst. Current design readily delivers a maximum current density up to 20 mA cm-2 and photovoltage of > 1.8 V, which is sufficient to drive an unassisted PEC water splitting reaction to produce H2 fuel with expected solar-to-hydrogen efficiency up to ~20%.  

    Specific points of attention to this project are:

      1. PEC Device Fabrication: PVSK-Si monolithic tandem photoelectrode with decoupled electrocatalytic and optical interfaces will be fabricated via both n-i-p or p-i-n architectures. To this end, specific attention will be paid to study the compatibility of PVSK-Si monolithic tandem device for PEC application by depositing appropriate metal catalyst with optimized thickness.


      2. Surface Passivation: Photoelectrode stability is a major challenge in PEC application. Additional passivation layer based on stable metal/metal-oxide (using ALD or vacuum deposition) is key to protecting the PVSK-Si monolithic tandem photoelectrode from photo-corrosion/photo-oxidation during PEC measurement under both aqueous electrolyte and light illumination conditions. This passivation strategy is expected to improve the long-term operational stability of photoelectrode.


      3. Atomically Thin 2D Catalyst Integration with PVSK-SI Photoelectrode. The absorption of light by electrocatalyst is a major problem in tandem PEC device with front side illumination configuration. For this reason, we aim to integrate optically transparent atomic 2D electrocatalyst, which not only enhances the PEC performance but also enables to construct unassisted water splitting system in a monolithic device.

      Project 2: Photocatalysis using triplet-triplet-annihilation-based energy up-conversion

      PI: Prof. Frederic Laquai

      In this project, we explore new hybrid photon-energy up-conversion systems, consisting of molecular up-converters, typically heavy metal-containing porphyrins combined with polyacene derivatives, anchored to catalytically-active metal oxide nanoparticles. This allows sensitization of large bandgap metal oxide semiconductors below their optical bandgap, which can be used to catalyze (photo)chemical reactions such as the reduction of carbon dioxide (CO2). A proof-of-principle of up-conversion-mediated photochemical reactions has already been demonstrated, and ongoing work focuses on optimizing reaction yields and on developing an in-depth understanding of the photophysical processes using spectroscopic experiments. 

      Project 3: Nano-reactors for water electrolysis using renewable energy

      PI: Prof. Thomas Anthopoulos

      In this project, we will integrate tandem solar cells with wafer-scale nanogap electrodes made of suitable metals (Pl, Al, Ti etc.) to produce planar electrochemical cells that can electrolyze even pure water (DI) while operating close to enthalpic potential of 1.48 V. We will employ dedicated set-ups to evaluate the relation between field-enhanced electrolysis and threshold voltage and the effect of continuous operation on electrodes’ structural integrity. The quality and dimensions of the metal electrode nanogaps will be experimentally evaluated through HR-TEM, AFM, STEM techniques.