Increased resistance to photooxidation in Dion-Jacobson lead halide perovskites -- implication for perovskite device stability

TL;DR

This study demonstrates that Dion-Jacobson lead halide perovskites exhibit enhanced resistance to photooxidation, leading to improved stability in solar cell applications, due to their lower propensity for organic cation deprotonation compared to Ruddlesden-Popper perovskites.

Contribution

The paper reveals that DJ perovskites' resistance to photooxidation stems from decreased double deprotonation events, offering a new understanding of stability mechanisms beyond structural differences.

Findings

DJ perovskites are less susceptible to photooxidation than RP perovskites.

Resistance is linked to reduced likelihood of organic cation deprotonation.

Enhanced stability improves operational lifespan of perovskite solar cells.

Abstract

2D metal halide perovskites have enabled significant stability improvements in perovskite devices, particularly in resistance to moisture. However, some 2D perovskites are even more susceptible to photooxidation compared to 3D perovskites. This is particularly true for more commonly investigated Ruddlesden-Popper (RP) perovskites that exhibit increased susceptibility to photoinduced degradation compared to Dion-Jacobson (DJ) perovskites. Comparisons between different RP and DJ perovskites reveal that this phenomenon cannot be explained by commonly proposed differences in superoxide ion generation, interlayer distance and lattice structural rigidity differences. Instead, the resistance to photooxidation of DJ perovskites can be attributed to decreased likelihood of double deprotonation events (compared to single deprotonation events in RP perovskites) required for the loss of organic cations and the perovskite decomposition. Consequently, DJ perovskites are less susceptible to oxidative degradation (both photo- and electrochemically induced), which leads to improved operational stability of solar cells based on these materials.