Predicting the electron affinity of ZnSiP2 semiconductor from first-principle calculations

Tandem photovoltaic architecture is an effective way to improve photoelectric conversion efficiency because of less thermalization loss. ZnSiP2 has the potential to meet the requirements needed for a top cell in tandem silicon-based solar cells. Electron affinity is an important electrical parameter of semiconductor materials, which has not been reported publicly in the literature on ZnSiP2. In this work, electron affinity of ZnSiP2 is investigated by using Vienna ab initio simulation package (VASP). PBE density functional method and HSE06 hybrid functional method are used to optimize the lattice structure and the hand structure, respectively. The results are as follows: the lattice constant of ZnSiP2 is 5.420 angstrom, and the hand gap is 2.048 eV. Based on the above work, the electron affinity of ZnSiP2 (001) crystal plane is calculated at different vacuum layer thicknesses, which is 3.056 eV at 16 angstrom vacuum layer. This work is helpful to the performance simulation and architectural design of ZnSiP2/Si tandem solar cells.