Two-dimensional series connected photovoltaic cells defined by ferroelectric domains.

Recently, a large amount of effort has been devoted to bringing p- and 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. [ABSTRACT FROM AUTHOR]