Switchable Photovoltaic Effect Induced by Light Intensity

Photovoltaic devices capable of reversible photovoltaic polarity through external signal modulation may enable multifunctional optoelectronic systems. However, such devices are limited to those induced by gate voltage, electrical poling, or optical wavelength by using complicated device architectures. Here, we show that the photovoltaic polarity is also switchable with the intensity of incident light. The modulation in light intensity induces photovoltaic polarity switching in geometrically asymmetric MoS₂ Schottky photodiodes, explained by the asymmetric lowering of the Schottky barrier heights due to the trapping of photogenerated holes at the MoS₂/Cr interface states. An applied gate voltage can further modulate the carrier concentration in the MoS₂ channel, providing a method to tune the threshold light intensity of polarity switching. Finally, a bidirectional optoelectronic logic gate with "AND" and "OR" functions was demonstrated within a single device.