Flexible and efficient ITO-free semitransparent perovskite solar cells

Semitransparent perovskite solar cells (PeSCs) with high efficiency and flexibility are demonstrated by using ultrathin Au and dielectric/metal/dielectric multilayered films as bottom and top electrode, respectively. An overall power conversion efficiency (PCE) of 8.67% and an average light transmittance (ALT) of 15.94% in the wavelength range of 500–2000 nm were obtained for the PeSCs. The ALT can be further increased to 31.61% by reducing the thickness of the bottom Au electrode. Furthermore, the PeSCs show excellent flexibility and mechanical robustness, and the PCE maintains 88% of their original efficiencies after 1000 bending cycles with a bending radius of 3.9 mm.