Multiscale Computational Design of Functionalized Photocathodes for H2 Generation.
Kara KearneyAshwathi IyerAngus RockettAleksandar StaykovElif ErtekinPublished in: Journal of the American Chemical Society (2017)
We present an integrated computational approach combining first-principles density functional theory (DFT) calculations with wxAMPS, a solid-state drift/diffusion device modeling software, to design functionalized photocathodes for high-efficiency H2 generation. As a case study, we have analyzed the performance of p-type Si(111) photocathodes functionalized with a set of 20 mixed aryl/methyl monolayers, which have a known synthetic route for attachment to Si(111). DFT is used to screen for high-performing monolayers by calculating the surface dipole induced by the functionalization. The trend in the calculated surface dipoles was validated using previously published experimental measurements. We find that the molecular dipole moment is a descriptor of the surface dipole. wxAMPS is used to predict the open-circuit voltage (efficiency) of the photocathode by calculating the photocurrent versus voltage behavior using the DFT surface dipole calculations as inputs to the simulation. We find that Voc saturates beyond a surface dipole of ∼0.3 eV, suggesting an upper limit for achievable device performance. This computational approach provides a possibility for the rational design of functionalized photocathodes for enhanced H2 generation by combining the angstrom-scale results obtained using DFT with the micron-to-nanometer scale capabilities of wxAMPS.
Keyphrases
- density functional theory
- molecular dynamics
- quantum dots
- high efficiency
- solid state
- molecular docking
- systematic review
- molecularly imprinted
- randomized controlled trial
- room temperature
- molecular dynamics simulations
- single molecule
- high resolution
- mass spectrometry
- ionic liquid
- single cell
- liquid chromatography
- data analysis