Dual passivation of SnO2/Perovskite heterogeneous interfacial defects for efficient perovskite solar cells

Abstract

The presence of heterogeneous interfacial defects limits the efficiency and long-term stability of the perovskite solar cells (PSCs). Rational passivation of interfacial defects and reduction of nonradiative recombination at the perovskite active layer are effective ways to achieve efficient PSCs. Here, a heterointerface engineering strategy is presented by employing a multifunctional molecule of reduced l -glutathione (GSH). The introduction of GSH improves the crystallization of SnO 2 , resulting in a continuous and conformal coverage of SnO 2 on the FTO surface. And the GSH buffer layer improves the affinity between SnO 2 and perovskite, resulting in the formation of large grains of perovskite. In addition, GSH bridges the perovskite to SnO 2 through multi-dentate ligands (-COOH, –NH 2 , –CONH–, –HS), which passivates the multiple defects at the heterogeneous interfaces while accelerates the electron transport. As a result, the PCE of the GSH-SnO 2 ETL based PSC significantly increases to 21.66% with no noticeable hysteresis. Meanwhile, compared with the control PSC, the unencapsulated GSH-SnO 2 based PSC exhibits better environmental stability, which maintains more than 80% of its initial PCE after 600 h of placement in atmospheric environment. GSH bridges the perovskite to SnO 2 through multi-dentate ligands, which passivates the multiple defects at the heterogeneous interfaces while accelerates the electron transport. • GSH-SnO 2 has a contiguous and conformal coverage on the FTO substrate. • Multidentate ligands dually passivate various defects at the SnO 2 /perovskite heterogeneous interface. • An electron transport bridge is constructed between SnO 2 and perovskite layer. • The GSH-SnO 2 based PSCs achieve an enhanced PCE of 21.66%.