Two-dimensional series connected photovoltaic cells defined by ferroelectric domains

Recently, a large amount of effort has been devoted to bringing p-A nd n-type two-dimensional (2D) materials in close contact to promise a p-n junction for photodetectors and photovoltaic devices. However, all solar cells based on 2D materials are single p-n junctions so far, where the open circuit voltage is usually limited by the bandgap of semiconductor materials. Here, by using a scanning-probe domain patterning method to polarize the ferroelectric film, we demonstrate a series connected MoTe₂ photovoltaic cell with an additive open circuit voltage and output electrical power. The nonvolatile MoTe₂ p-n diodes exhibit a rectification ratio of 100. As a photodetector, the device presents a responsivity of 220 mA/W and an external quantum efficiency of 41% without any gate or bias voltages. The open circuit voltage increases linearly with the number of series connected p-n junctions and can be beyond the bandgap of the multilayer MoTe₂.