Application of lead-free BaZr0.1Ti0.9O3 in polarized tunable charge transfer perovskite solar cells

In this article, we provide the evidence of domain wall (DW) conduction in 90° BaZr0.1Ti0.9O3 (BZT) DWs by density functional theory (DFT) calculations. Experimental characterizations prove the existence of ferroelectric domains and DWs in as-prepared BZT films, and the measured electrical conductivity of the BZT films reaches ∼2.53 × 10−4 S/cm, which further confirms DW conduction. Furthermore, we designed BZT-based polarization tunable photovoltaic devices with DW conduction. The rearrangement of interfacial type-II band alignment upon different poling tends to regulate the charge transfer across the interface, confirmed by DFT calculations, resulting in a ferroelectric-tunable photovoltaic property. A positive polarization tends to improve the photovoltaic performance of the device, which has also been well verified in the experiments. Zr ion-implanted BaTiO3 provides a new route to fabricate an electronic transfer layer for high-efficiency perovskite solar cells. Our results reveal the mechanism of DW conduction, inspiring future improvements of photovoltaic devices which can be tuned by ferroelectric polarization.