Planar MgxZn1-xO-based perovskite solar cell with superior ultraviolet light stability

Generally, TiO2-based perovskite solar cell (PSC) is beneficial to high efficiency but poor ultraviolet (UV) light stability. Here, we report that a highly efficient MgxZn1-xO-based (MZO-based) PSC with excellent UV light stability. MZO has a higher electron mobility and deeper conduction band than traditional TiO2, which can reduce the charge accumulation at the MZO/perovskite interface and enhance the charge transfer from perovskite to MZO. Furthermore, the reduced interface loss and energy barrier are beneficial to obtain high open-circuit voltage (Voc). By optimizing, the MZO-based device shows a high Voc of 1.11 V, yielding a promising efficiency of 19.57%. The MZO-based device (unencapsulated) retains 76% of its initial short-circuit current density (Jsc) after 1 year air aging (room temperature, relative humidity: 40–80%) and 8 h UV irradiation (365 nm, 35 W), versus only 12% under the same condition for TiO2-based device. The good UV light stability of MZO-based device can be attributed to the reduced electron trap-state density in MZO electron-transporting layer (ETL). Specifically, zinc interstitial and oxygen vacancy mediated defect sites of MZO ETL are effectively passivated, which tightly protects the perovskite layer from degradation under UV light. Our results show a great potential for MZO ETL application in UV-stable PSC. [Display omitted] •A wet-chemical route for low-temperature MgxZn1-xO nanocrystals is reported.•The champion PCE of MgxZn1-xO-based perovskite solar cell is 19.57%.•The Voc is 1.11 V, keeping up with that (1.11 V) of SnO2-based n-i-p device.•Device retains 76% of initial Jsc after 1 year air aging and 8 h UV irradiation.