Dynamic monitoring of the light-soaking effect of organic–inorganic perovskite solar cells doped with alkali metal ions

Abstract

Metal halide perovskites (MHPs) have been demonstrated to exhibit mixed ionic and electron conductive properties, characterized by their remarkable soft lattice features. However, a full understanding of the complicated interplay between ion, lattice, and carrier recombination and the influence on the optoelectronic properties and performance of perovskite solar cells remains elusive. To this end, the present study utilized time-dependent photoluminescence (PL) spectroscopy to investigate the light-soaking effect of organic–inorganic perovskite solar cells doped with alkali metal ions (K⁺/Rb⁺) and undoped perovskite films under continuous illumination. Dynamic monitoring of the PL intensity and carrier lifetimes within 1–500 s of continuous illumination revealed significant influences of the alkali metal ions and light intensity on the performance, including the stability of the perovskite solar devices. The results reveal that K⁺/Rb⁺ doping in perovskite films induces more positive light-soaking effects. These effects include enhanced PL intensity, inhibited phase separation, and prolonged carrier lifetime. The synergistic combination of these effects leads to the improved photoelectric conversion efficiency and device stability of perovskite solar cells (PSCs). These findings offer novel insights into the roles of ions in MHPs and are pivotal for comprehending the mechanisms underlying MHP devices, particularly concerning the ionic properties of MHPs.