Energy and charge transfer cascade in methylammonium lead bromide perovskite nanoparticle aggregates

Abstract

Evidence for an ultrafast light-induced cascade of energy and charge transfer between aggregated quantum-confined nanoplatelets and nanoparticles of CH3NH3PbBr3 perovskite.

Micron-Size Two-Dimensional Methylammonium Lead Halide Perovskites

“…This PL emission at lower energy is likely due to an energy cascade mediated by excitonic charge transfer from high energy, quantum confined regions to lower energy bulk regions within the same nanosheets. 28 This is also known as energy funneling. 29 In this process, more confined, low n regions with larger bandgap transfer their energy via resonant energy or charge transfer processes to less confined, higher n regions with lower bandgap, where radiative emission occurs.…”

“…These observations agree with previous time-resolved spectroscopic studies for 2D perovskites. 28,29 The short DDA ligands used to prepare the MAPbBr sheets favored the energy funneling process. Synthesizing with longer TDA and HDA resulted in emission at higher energies ( Figure S16), away from the bulk, confirming that the energy transfer process is much weaker.…”

Methanol-induced fast CsBr release results in phase-pure CsPbBr3 perovskite nanoplatelets

“…38,39 By controlling the surface ligands, reaction temperature and additives, several shape variations of perovskite nanomaterials have been achieved, including NCs, nanorods, nanowires, and nanoplatelets (NPLs). [40][41][42][43][44][45][46][47][48] However, taking CsPbBr 3 as an example, even though the Cs : Pb : Br ratio is set precisely to 1 : 1 : 3 in the precursor, the nal products are always accompanied by CsPb 2 Br 5 impurities, which are known as nonemissive wide bandgap components. [49][50][51][52] These impurities introduce undesired energy states and act as charge blockers, decreasing the charge mobility.…”

Coherent Spin and Quasiparticle Dynamics in Solution‐Processed Layered 2D Lead Halide Perovskites

“…Early photophysics studies in 2D perovskites were mainly limited to their linear properties;10, 15, 16 while studies on their transient photophysics are few and far between 17, 18, 19. In particular, transient optical spectroscopy takes on a leading role in understanding these unusual phenomena and in unlocking the latent potential of these novel materials 20.…”