Pressure-induced non-radiative losses in halide perovskite light-emitting diodes

Abstract

The control of non-radiative losses in light-emitting diodes (LEDs) based on metal halide perovskites is crucial to improve device efficiency. Recent studies have shown a correlation between lattice strain and...

From optical pumping to electrical pumping: the threshold overestimation in metal halide perovskites

“…, angle-resolved photoemission (ARPES) results 31 and circular photogalvanic effect together with spatially resolved photoinduced inverse spin Hall effect measurements; 32 (2) the PbBr 6 octahedral thermal polar distortions at elevated temperatures can lead to a dynamical Rashba splitting effect; 33 (3) the strain inside the perovskite thin film can cause PbBr 6 octahedral distortion, increasing the possibility of the Rashba splitting effect. 34 Such unique band structure enables the two-photon absorption process that excites the electrons into a high energy band with opposite spins following the selection rule Δ J = ±2, while the one-photon absorption only occurs between two bands with the same spin (Δ J = ±1). As the momentum difference for cooling is smaller, the relaxation of the carriers excited via two-photon absorption to the bottom of the band is much faster compared to one-photon absorption with the same energy.…”

“…29 Although the crystal bulk of our MAPbBr 3 perovskite is a centrosymmetrical structure, 30 symmetry breaking can still occur for the Rashba splitting effect in the polycrystalline thin film based on the following considerations: (1) symmetry breaking forms at the perovskite interface due to the asymmetric perovskite/ambient layout, as evidenced by many different experimental characterizations based on the MAPbBr 3 single crystal, e.g., angleresolved photoemission (ARPES) results 31 and circular photogalvanic effect together with spatially resolved photoinduced inverse spin Hall effect measurements; 32 (2) the PbBr 6 octahedral thermal polar distortions at elevated temperatures can lead to a dynamical Rashba splitting effect; 33 (3) the strain inside the perovskite thin film can cause PbBr 6 octahedral distortion, increasing the possibility of the Rashba splitting effect. 34 Such unique band structure enables the two-photon absorption process that excites the electrons into a high energy band with opposite spins following the selection rule DJ = AE2, while the one-photon absorption only occurs between two bands with the same spin (DJ = AE1). As the momentum difference for cooling is smaller, the relaxation of the carriers excited via two-photon absorption to the bottom of the band is much faster compared to one-photon absorption with the same energy.…”

Origins, Impacts, and Mitigation Strategies of Strain in Efficient and Stable Perovskite Solar Cells

“…[65] Calculations based on relativistic first principles show that under compression strain, the octahedra are deformed by pressure, and as a result, the cation spins to fit into the cavity. [66] Especially, under high pressure, perovskite films exhibit completely amorphized or irreversible phase transformations, which have diverse effects on the properties of perovskite, depending on its composition. [67] In short, several external condition-induced strains can affect the perovskite's properties; this might have an impact on how well the relevant optoelectronic devices work, either positively or negatively.…”

“…[ 65 ] Calculations based on relativistic first principles show that under compression strain, the octahedra are deformed by pressure, and as a result, the cation spins to fit into the cavity. [ 66 ] Especially, under high pressure, perovskite films exhibit completely amorphized or irreversible phase transformations, which have diverse effects on the properties of perovskite, depending on its composition. [ 67 ]…”

Inhomogeneous Defect Distribution in Mixed-Polytype Metal Halide Perovskites

“…For the case of homogeneous hydrostatic strain in a purely corner-sharing perovskite, lattice expansion makes iodine vacancy formation less favorable. 24 The behavior is different here as the strain is nonuniform with an elastic dipole centered around the interfacial iodide layer that reduces the defect formation energy.…”