Novel Hole Selective CrO x Contact for Dopant-free Back Contact Silicon Solar Cells

•The dopant-free back contact solar cells are demonstrated based on hole selective contact material, chromium trioxide (CrOx, x < 3) with a low melting point for high stability and high performance.•CrOx is first applied in silicon based solar cell as the emitter.•The back contact solar cell which demonstrated an efficiency of 15.8% and high stability was fabricated, by implementing the multilayer films of CrOx (5 nm)/Au (4 nm)/ CrOx (5 nm) capped by Ag (500 nm) as the emitter.