Making a benign buried bottom interface for high-performance perovskite photovoltaics with a chelating molecule

Abstract

Interfacial modifications can significantly enhance the photovoltaic performance of perovskite solar cells (PSCs). We introduced an auxiliary chelating agent, 5,6-isopropyridine-L-ascorbic acid (ILAA), to modify the SnO2/perovskite buried interface. By a non-destructive peeling process using a UV epoxy glue, we exposed the buried bottom of the perovskite layer for direct examination. ILAA not only suppressed SnO2 defects and hydroxyl oxygen but also prevented deterioration of the buried bottom of the perovskite layer. Theoretical calculations also confirmed the greater competitiveness of ILAA in interacting with perovskite molecules than dimethyl sulfoxide. The introduction of ILAA optimized the energy band structure of the SnO2-perovskite interface, therefore enhanced the built-in electric field and facilitated efficient charge transfer. Consequently, ILAA-modified PSCs achieved power conversion efficiencies of 24.04 % and 19.10 % for microdevices (0.09 cm2) and modules (19.32 cm2), respectively. These unencapsulated devices exhibited excellent humidity and thermal stability, maintaining over 80 % of their initial performances after being aged in air for 1000 h or continuously heated for 500 h.