Intact 2D/3D Halide Junction Perovskite Solar Cells via Solid-Phase In-Plane Growth (SIG)

Ruddlesden-Popper two-dimensional perovskite(2D perovskite) layer embedded in the junction between the hole transport layer and the 3D perovskite(3D-dimensional) of the solar cell not only modifies the surface of the photoactive layer but also promotes hole extraction from 3D perovskite. However, 2D/3D halide perovskite bilayer obtained through the solution process contains quasi-two-dimensional perovskite which limits us to designing an appropriate local electric field for efficient carrier collection.<br/>Growing a stable and highly crystalline 2D(C₄H₉NH₃)2PbI4 film on a 3D film using solvent-free ‘Solid-state In-plane Growth(SIG)’ method can produce an intact 2D/3D heterojunction, thereby enhancing the inner built-in potential of the device[1]. Without a liquid phase precursor, the SIG process is possible to form a 2D perovskite with target thickness that could maximize the depletion region and built-in potential. Proper 2D/3D heterojunction furnishes the solar cell with a certified steady-state efficiency of 24.35% and an open-circuit voltage of 1.185 V.<br/>A high crystalline 2D perovskite layer blocks the release of the cation from 3D perovskite and the inrush of external moisture, providing stability. Encapsulated SIG-based device maintains 94% of the initial efficiency after 1,056 h in the damp heat test (85°C/85% relative humidity) and 98% after 1,620 h under solar lighting. This is the closest technology to commercialization which can make perovskite solar devices with high efficiency (over 24%) and high stability at the same time.<br/><b>Reference</b><br/>[1] Jang, YW., Lee, S., Yeom, K.M. et al. Intact 2D/3D halide junction perovskite solar cells via solid-phase in-plane growth. Nat Energy 6, 63–71 (2021). https://doi.org/10.1038/s41560-020-00749-7