A Capacitor-type Faradaic Junction for Direct Solar Energy Conversion and Storage

Two-electrode solar rechargeable devices trigger intense attention due to their potential applications in solar energy conversion and storage. However, interface energy barriers lead to severe loss of output voltage and negligible dark discharge current. Therefore, external biases are required for dark discharge in these devices, limiting their practical applications. Herein, we report a new two-electrode device of Si/WO₃/H₂SO_4(aq)/C that can work without bias. The device has the highest dark output power among all of the two-electrode solar rechargeable devices. The device based on a Si/WO₃ junction indicates photoinduced adjustable interface barrier height during charge transfer, which can overcome the energy barrier and realize dark discharge without bias. Owing to the interface characteristics, the Si/WO₃ is designated as a capacitor-type Faradaic junction.