High-Throughput Computational Screening of Chromophores for Dye-Sensitized Solar Cells

Electron injection from a photoexcited chromophore into semiconductor (TiO2) nanoparticles is one of the key electron transfer processes in dye-sensitized solar cells. We describe our model for calculations of electron injection times, which is based on partitioning the semiconductor chromophore system into fragments (TiO2 slab with adsorbed chromophore's anchoring group, and an isolated chromophore), and calculating the imaginary part of the self-energy from the electronic properties of the fragments: density of states of TiO2 slab, TiO2-anchoring group coupling, and chromophore's wave function coefficients. The electronic properties of the semiconductor and its interface with the chromophore's anchoring group are reused for all chromophores with the same anchoring group (carboxylic acid in this study), and only a calculation of the isolated chromophore's lowest unoccupied molecular orbital is required for each chromophore. We use this model to calculate electron injection times for a large set of organic chromophores, including, e.g., perylene dyes and biisonicotinic acid, on TiO2 rutile (110) and anatase (101) surfaces. The calculated injection times are in good agreement with reported experimental injection times or light conversion efficiencies of solar cells based on these dyes. Our model is computationally efficient and allows us to make reliable predictions of electron injection times for families of chromophores sharing the same adsorption chemistry.