Full in silico DFT characterization of lanthanum and yttrium based oxynitride semiconductors for solar fuels

摘要

Finding new solar-energy absorber materials is one of the most significant challenges in artificial photosynthesis. Starting from the experimentally available LaTaON2 and LaTiO2N oxynitrides, we use DFT to propose new sunlight absorbing semiconductors. The synthetically unknown YTaON2 and YTiO2N are semiconductors with indirect band gaps of 2.7 eV and 2.9 eV, respectively. For the first time, we compute within Boltzmann transport theory the DOS-averaged effective mass and mobility of LaTaON2, LaTiO2N, YTaON2 and YTiO2N. Our first principles calculations indicate that the Y-based materials possess advantageous dielectric (epsilon(r) 47), optical ( 10(4) cm(-1) near band edge), and charge transport properties (m(e,h)*(DOS) approximate to 0.2; (e,h) approximate to 10(2) cm(2) V-1 s(-1)) for the conversion of solar energy into storable fuels. Herein, our work leads to the complete in silico design of semiconductors for water splitting.