摘要： This work presents theoretical investigations on the spontaneous-radiation loss of two-dimensional van der Waals heterojunction photovoltaic cells (2D-PVcs) combined with an interference-based light-trapping structure. We find that 2D-PVcs possess much lower spontaneous radiation loss, since the solid angle of the spontaneous radiation is a magnitude smaller than that in traditional PVcs. The efficiency limit of a 2D-PVc can be 10% larger than that of a traditional PVc. Furthermore, we demonstrate that the spontaneous-radiation loss can be further reduced by introducing only a weak light-concentrating system, approaching the efficiency limit of traditional PVcs under perfect focus. In a trapped structure, the smaller the light absorption coefficients of the photovoltaic cells, the higher are the efficiency limits that are achieved. Finally, the spontaneous-radiation loss increases as the battery thickness increases, indicating that the 2D-PVc has the lowest spontaneous emission loss because of its extremely low thickness.