Device Simulation of 25.9% Efficient ZnOxNy${\rm ZnO}_x{\rm N}_y$/Si Tandem Solar Cell

Abstract The novel, high electron mobility material has been investigated theoretically as an absorber in a two‐terminal tandem solar cell. In addition to its high mobility, can attain sufficiently low carrier concentration to enable ‐junctions, and has a tunable bandgap around the 1.7 eV range. It is therefore suitable for pairing with a Si‐based bottom cell. In addition to the layer, the tandem cell consists of a emitter and a Si heterojunction bottom cell. A buffer layer is introduced between the emitter and absorber in the top cell to mediate a large valence band offset that resulted in a poor fill factor, . A buffer layer bandgap of 1.5 eV gave the highest power conversion efficiency (PCE). The objective is to estimate the optimal performance of in a tandem solar cell. The dependence of current–voltage (–) characteristics on thickness, mobility and carrier concentration in the layer is evaluated, and found to yield maximum performance with 0.35 , 250 Vs –1 and , respectively. Using these conditions, the – parameters of the device under AM1.5 illumination are short circuit current density, mA , open circuit voltage, V, and . With this, it is reported on, to the best of the knowledge, the first device simulation based on .