Halide perovskite (HP) solar cells have shown great promise, demonstrating power conversion efficiencies beyond 25 %. However, to enable marked deployment, HP solar cell stability should be also improved. Large cations have been introduced at the HP interfaces with charge transport layers to passivate point defects in the films, enabling the latest efficiency records. In this contribution we investigate the thermal stability of these passivation layers. We process HP solar cells with efficiencies &gt;20 % and we demonstrate – combining XPS, UPS, and GIWAXS measurements - that heating causes the bulky cations used for passivation to diffuse in the 3D perovskite film, affecting the passivation capabilities of the layer and resulting in loss of conductivity at the interface; both effects limiting the solar cell stability. Based on our findings we then propose design rules to enable deposition of thermally stable 2D passivation layers.

The frailty of 2D passivation in efficient perovskite solar cells

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.