Optimized crystallization and defect passivation with Yttrium (III) doped MAPbBr3 film for highly efficient and stable hole-transport-layer-free carbon-based perovskite solar cells

•Y3+ ions were incorporated into MAPbBr3 films through a precursor engineering method.•The better crystallinity, lower trap density and longer carrier lifetime of perovskite absorber as obtained.•The MAPb0.98Y0.02Br3 PSCs achieved a higher PCE of 8.313% with a VOC of 1.562 V.•Y3+-doped MAPbBr3 devices exhibited long-term stability in harsh environment. Y3+ ions are incorporated into MAPbBr3 lattice through a precursor engineering method, the appropriate introduction of Y3+ ions can considerably suppress the charge recombination and increase carrier lifetimes. The hole-transport-layer-free carbon-based MAPb0.98Y0.02Br3 PSCs achieve a higher PCE of 8.313% with a VOC of 1.562 V. More importantly, the un-encapsulated device also shows remarkable long-term stability under high temperature and high humidity in ambient conditions. [Display omitted] The preparation of high-quality perovskite films with low defect density and long carrier lifetime is a precondition for achieving high-efficiency perovskite solar cells (PSCs). In this work, we successfully incorporated Y3+ ions into perovskite films to enhance the photovoltaic performance of hole-transport-layer-free (HTL-free) carbon-based MAPbBr3 PSCs in ambient atmosphere. The perovskite films exhibit better crystallinity, lower trap density, and longer carrier lifetime after the introduction of Y3+ ions. By optimizing the doping dosage, a maximal power conversion efficiency (PCE) of 8.313% (open-circuit voltage (VOC) = 1.562 V) is achieved for MAPb0.98Y0.02Br3 PSCs. Moreover, the unencapsulated device also shows remarkable long-term stability over 80 days under dry condition with 20–30% relative humidity (RH) at 20–25 °C, which even maintains 95% of its initial PCE when stored in harsh environment (80 °C and 40–70% RH) over 72 h.