26 September 2022
Deterministic fabrication of 3D/2D perovskite bilayer stacks for durable and efficient solar cells
(Science 2022) Realizing solution-processed heterostructures is a long-enduring challenge in halide perovskites because of solvent incompatibilities that disrupt the underlying layer. By solvent fine tuning, we could grow phase-pure two-dimensional (2D) halide perovskite bilayer stacks of the desired composition, thickness, and bandgap onto 3D perovskites without dissolving the underlying substrate. Thickness dependence of the 2D perovskite layer reveals the anticipated trends for n-i-p and p-i-n architectures, which is consistent with band alignment and carrier transport limits for 2D perovskites. We measured a photovoltaic efficiency of 24.5%, with exceptional stability of T99 (time during which the efficiency remains above 99% of its initial value) of >2000 hours, implying that the 3D/2D bilayer inherits the intrinsic durability of 2D perovskite without compromising efficiency.
