Ultra-large dipole moment organic cation derived 3D/2D p-n heterojunction for high-efficiency carbon-based perovskite solar cells

The organic spacer cation with ultra-large dipole moment results in the formation of p-type 2D perovskites and 3D/2D p–n junctions. The hole transport layer-free carbon-based perovskite solar cells achieve an efficiency of 20.08%.