Earth-abundant ZnSnxGe1−xN2 alloys as potential photovoltaic absorber materials

Large-scale energy demands will require low-cost, earth-abundant materials for high efficiency solar energy conversion. Here we present ZnSn_xGe_1-xN₂ as a tunable band gap photovoltaic absorber layer with a predicted range of 1.4 eV to 2.9 eV. Thin films of ZnSn_xGe_1-xN₂ are synthesized by reactive RF co-sputtering with a wide range of compositions. X-ray diffraction shows a linear shift in lattice parameter with changing composition, indicating no phase separation. These results suggest that ZnSn_xGe_1-xN₂ can potentially be tuned to span a large portion of the solar spectrum and could therefore be a viable earth-abundant photovoltaic material.