The Physics of Interlayer Exciton Delocalization in Ruddlesden–Popper Lead Halide Perovskites

Abstract

Two-dimensional (2D) lead halide Ruddlesden–Popper perovskites (RPP) have recently emerged as a prospective material system for optoelectronic applications. Their self-assembled multi quantum-well structure gives rise to the novel interwell energy funnelling phenomenon, which is of broad interests for photovoltaics, light-emission applications, and emerging technologies (e.g., spintronics). Herein, we develop a realistic finite quantum-well superlattice model that corroborates the hypothesis of exciton delocalization across different quantum-wells in RPP. Such delocalization leads to a sub-50 fs coherent energy transfer between adjacent wells, with the efficiency depending on the RPP phase matching and the organic large cation barrier lengths. Our approach provides a coherent and comprehensive account for both steady-state and transient dynamical experimental results in RPPs. Importantly, these findings pave the way for a deeper understanding of these systems, as a cornerstone crucial for establishing material design rules to realize efficient RPP-based devices.

Tailoring the Energy Manifold of Quasi‐Two‐Dimensional Perovskites for Efficient Carrier Extraction

“…Recently, our group also demonstrated a possibility of an ultrafast coherent localization of excitation in high-n QWs. [21] Such energetic disorder is proposed as a possible cause of the differences in the reported dynamics of the energy cascade. [16] In the context of average excess energy loss of carriers, the coherent process will facilitate sub-ps localization of carriers into high-n QWs (out-competing extraction, that we estimated previously to be of the order of tens of ps) where BCP can no longer extract them.…”

“…[17,18] This cascade proceeds via energy or charge transfer processes among the QWs in timescales up to several hundred ps. [19][20][21][22] This energy funneling approach has already been harnessed to realize highly efficient light-emitting diodes, [23,24] ultrafast charge and spin transport, [25][26][27] solar cells, [28][29][30][31][32] etc.…”

Interlayer Triplet-Sensitized Luminescence in Layered Two-Dimensional Hybrid Metal-Halide Perovskites

“…A recent theoretical work by Giovanni and co-workers revealed that in Ruddlesden–Popper perovskites, exciton delocalization across multiple quantum wells may be responsible for coherent Dexter-like energy transfer between layers . Furthermore, their model suggests that coherent energy funneling is most pronounced in low n phases, which have dominated experimental studies of interlayer energy transfer.…”

The photophysics of Ruddlesden-Popper perovskites: A tale of energy, charges, and spins

“…Here, the authors demonstrate that excitons in PEPI are delocalized for about 10 nm in the direction perpendicular to the barriers [143]. It is noteworthy that these subbands could provide a mechanism for ultrafast and coherent energy transfer: this would be possible in mixed RPs by the excitation of a selected n-phase and the subsequent collapse of the delocalized wavefunction on higher n-phase at lower energy [144].…”