Formation of BaSi₂ heterojunction solar cells using transparent MoO_x hole transport layers

Heterojunction solar cells that consist of 15 nm thick molybdenum trioxide (MoO_x, x < 3) as a hole transport layer and 600 nm thick unpassivated or passivated n-BaSi₂ layers were demonstrated. Rectifying current-voltage characteristics were observed when the surface of BaSi₂ was exposed to air. When the exposure time was decreased to 1 min, an open circuit voltage of 200 mV and a short circuit current density of 0.5 mA/cm² were obtained under AM1.5 illumination. The photocurrent density under a reverse bias voltage of −1 V reached 25 mA/cm², which demonstrates the significant potential of BaSi₂ for solar cell applications