Surface passivation by thin-slab 2D perovskites is an effective method to suppress interfacial carrier recombination of 3D metal halide perovskite photoabsorbers. However, improving device performance by integrating such 2D/3D perovskite heterojunctions in the sunward, transparent contacts of perovskite solar cells is not evident due to the high exciton binding energies of phase-pure 2D perovskites, which may result in inefficient free-carrier generation and collection. Here, we overcome this challenge by tuning the dimensionality of 2D perovskites via structural isomers of butylammonium (BA) as a small organic cation, occupying the A-site of the 2D perovskite lattice. The discontinuous iso-BA-based 2D crystals on the 3D perovskite surface yield improved interfacial passivation and enhanced hole extraction. Besides an increased open circuit voltage, this remarkably leads to an enhanced photocurrent (∼1 mA cm−2) compared with control perovskite solar cells, resulting in bifacial perovskite/silicon tandem solar cells with power generation densities >27 mW cm−2.
- 2D/3D perovskite heterojunction
- bifacial tandem solar cells
- MAP5: Improvement
- perovskite/silicon tandem solar cells
ASJC Scopus subject areas
- Materials Science(all)