![]() ![]() ![]() These effects can, however, be captured using atomistic models based on density functional theory (DFT). DFT combined with the non equilibrium Green’s function (NEGF) formalism was f.ex. previously used to improve a continuum model study of transport through the interface between CZTS and the buffer material CdS important for the CZTS solar cell efficiency Crovetto et al. In spite of the influx of new thin film based PV cells, silicon remains the market leader and about 90 % of PV cells are still based on silicon where large modules with high efficiency and stability can be produced Philipps and Warmuth ( 2017). Silicon has an indirect bandgap and as such absorption of a photon around the bandgap energy must be accompanied by the absorption/emission of a phonon to conserve momentum. The study of phonon-assisted photon absorption from first-principles is notoriously difficult as it involves a double sum over fine grids of k points and complex two excitation processes.Ī number of recent studies also show that EPC plays a key role in the outstanding performance of perovskite PV cells Yang et al. Therefore state-of-the-art DFT calculations of phonon-assisted absorption has so far been limited to bulk crystals where the supercell contains only a few atoms Noffsinger et al. Recently, Zacharias and Guistino Zacharias and Giustino ( 2016) introduced a very efficient method for including phonon induced absorption processes using a single super cell calculation in which the atoms are displaced away from their equilibrium positions. We recently adopted this Special Thermal Displacement (STD) approach to study electron transport in silicon systems with over 1000 atoms including electron-phonon coupling within the DFT-NEGF formalism Gunst et al. ![]() ![]() In this paper we apply STD to calculations of the first order photocurrent in a 19.6 nm silicon p-n junction from DFT-NEGF. ![]()
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