Universal scaling laws for charge-carrier interactions with quantum confinement in lead-halide perovskites

Abstract

Lead halide perovskites open great prospects for optoelectronics and a wealth of potential applications in quantum optical and spin-based technologies. Precise knowledge of the fundamental optical and spin properties of charge-carrier complexes at the origin of their luminescence is crucial in view of the development of these applications. On nearly bulk Cesium-Lead-Bromide single perovskite nanocrystals, which are the test bench materials for next-generation devices as well as theoretical modeling, we perform low temperature magneto-optical spectroscopy to reveal their entire band-edge exciton fine structure and charge-complex binding energies. We demonstrate that the ground exciton state is dark and lays several millielectronvolts below the lowest bright exciton sublevels, which settles the debate on the bright-dark exciton level ordering in these materials. More importantly, combining these results with spectroscopic measurements on various perovskite nanocrystal compounds, we show evidence for universal scaling laws relating the exciton fine structure splitting, the trion and biexciton binding energies to the band-edge exciton energy in lead-halide perovskite nanostructures, regardless of their chemical composition. These scaling laws solely based on quantum confinement effects and dimensionless energies offer a general predictive picture for the interaction energies within charge-carrier complexes photo-generated in these emerging semiconductor nanostructures.

Spectral Fingerprint of Quantum Confinement in Single CsPbBr3 Nanocrystals

“…This dependency is similar to recent results on slightly larger-sized CsPbBr 3 NCs as a function of the emission energy, which reported trion and biexciton binding energies up to 16 and 35 meV, respectively. 28,29 To recover the bulk energy shifts and the size dependence of the energy shifts, we use a simple empirical law of the form A + B/L 2 . We find bulk energy shifts A X* = −10 meV and A XX = −16.5 meV, and a size dependence given by B Xd * = −780 meV•nm 2 and B XX = −1370 meV•nm 2 .…”

Biexciton-like Auger Blinking in Strongly Confined CsPbBr3 Perovskite Quantum Dots

“…Although attractive biexciton interactions are frequently reported in perovskite NCs, 14,[16][17][18][19]23,[26][27][28][29][30][31]40 these studies focused mostly on larger, weakly confined NCs (we also observed attractive biexciton interaction in our larger perovskite NCs). Additionally, many reported measurements are performed at cryogenic temperatures.…”

“…Perovskite quantum dots (QDs) have emerged as promising single-photon emitter (SPE) materials because of their high photoluminescence (PL) quantum yield (QY) and fast radiative emission rate. − For SPEs based on single QDs, high photoexcitation rates increase the brightness at a cost of single-photon purity due to multiexciton generations. ,, Strongly confined perovskite QDs (SCPQDs), which are smaller than their exciton Bohr diameters, can effectively annihilate multiexciton emissions through nonradiative Auger recombination. − However, SCPQDs are notorious for their poor surface chemical stability, especially under intense photoexcitation . This has significantly curtailed the understanding of intrinsic exciton dynamics and many-body effects such as biexciton interactions − in perovskite QDs for their applications on SPEs.…”

“…Recently, a postsynthetic ligand treatment was developed and enabled spectroscopic studies of single-quantum confined perovskite QDs . Although intensive single-particle studies have revealed the exciton fine structures ,− ,, and global features of the biexciton binding energy − in weakly confined perovskite QDs, studies of single SCPQDs are very limited due to their insufficient PL stabilities; the stochastic PL intensity fluctuations (often termed blinking) between the exciton (ON) state and the trion (OFF) state are still prominent. − …”

2D multilayered perovskites and 2D/3D bilayers for stable solar cells

“…They especially exhibit very small shear elastic moduli. At the microscopic level, these unusual features are basically explained by the very strong anharmonicity of the lattice [10,11], and in-plane and out-of-plane octahedra tilting modes leading to additional lattice strain [12]. For a pure in-plane antiferrodistorsive octahedra rotation defined by the angle 𝛽 (Figure 2), the in-plane lattice parameter is given by a non-linear relation to :…”