Phase-pure two-dimensional layered perovskite thin films

Zero-dimensional mixed-cation hybrid lead halides with broadband emissions

“…This confirms the presence of more than one PL centre, which could be assigned to STE emission. Similar broadband and strongly Stokes shifted emissions have been reported for many low-dimensional lead halide perovskites, 19,20,44,52,54–56 including 0D. 29–36,53,57 Table S6† shows that Cs 2 MHy 2 PbBr 6 and Cs 2 MHy 2 PbBr 3 I 3 exhibit a record large Stokes shift among 0D lead halides.…”

“…This confirms the presence of more than one PL centre, which could be assigned to STE emission. Similar broadband and strongly Stokes shifted emissions have been reported for many low-dimensional lead halide perovskites, 19,20,44,52,[54][55][56] including 0D. [29][30][31][32][33][34][35][36]53,57 To confirm the origin of the PL bands, we have also performed time-resolved measurements at 80 K under a 266 nm excitation line generated with a femtosecond laser.…”

Bilayer 2D-3D Perovskite Heterostructures for Efficient and Stable Solar Cells

“…For instance, the growth of phase-pure BA 2 PbI 4 ( n = 1) layer (∼80 nm) on top of a FA-based 3D perovskite film results in a p-p isotype heterojunction that can provide a satisfactory back-surface field for efficient hole transfer while introducing a barrier to the electron flow, which suppresses the interfacial nonradiative recombination for a significantly enhanced built-in potential compared to its mixed-phase counterpart . Given the undesirable type-I band alignment between different n domains in the mixed-phase 2D perovskite layer, the resultant energy band disorder may cause charge accumulation at the high- n domains to induce the chain decomposition of the 2D perovskite matrix layer . To address this issue, the phase-pure BA 2 MA 2 Pb 3 I 10 ( n = 3) capping layer (∼50 nm) was deterministically fabricated to form a type-II band alignment with the underlying 3D perovskite, which enables efficient hole extraction to mitigate the charge accumulation at the interface, thus leading to exceptionally stable bilayer 2D-3D PHSs with a negligible efficiency decay (<1%) after 2,000 h under operation in ambient conditions .…”

High-Performance Pure Red Quasi-Two-Dimensional Perovskite Light-Emitting Diodes with Bifunctional Potassium Trifluoroacetate Additive

“…The optimized energy transfer pathway with a concentrated phase distribution facilitates sufficient energy transfer and corresponding exciton radiative recombination. 26 Meanwhile, the widely existing defect-induced traps, especially deep traps, cause charge trapping and provide a nonradiative recombination pathway. 27,28 Therefore, efficient energy transfer and low defect density are the keys to achieving high-performance pure red quasi-2D PeLEDs.…”

“…Quasi-2D perovskites possess mixed phases with different n-values (n represents the thickness of inorganic octahedral [PbI 6 ] 4– layers), and cascade energy funneling occurs from low-n phase to high-n phase (emission phase). − Efficient energy transfer requires the rapid transfer of carriers to the emission phase to avoid the trapping process. The optimized energy transfer pathway with a concentrated phase distribution facilitates sufficient energy transfer and corresponding exciton radiative recombination . Meanwhile, the widely existing defect-induced traps, especially deep traps, cause charge trapping and provide a nonradiative recombination pathway. , Therefore, efficient energy transfer and low defect density are the keys to achieving high-performance pure red quasi-2D PeLEDs …”