Carriers, Quasi-particles, and Collective Excitations in Halide Perovskites

Abstract

Halide perovskites (HPs) are potential game-changing materials for a broad spectrum of optoelectronic applications ranging from photovoltaics, light-emitting devices, lasers to radiation detectors, ferroelectrics, thermoelectrics, etc. Underpinning this spectacular expansion is their fascinating photophysics involving a complex interplay of carrier, lattice, and quasi-particle interactions spanning several temporal orders that give rise to their remarkable optical and electronic properties. Herein, we critically examine and distill their dynamical behavior, collective interactions, and underlying mechanisms in conjunction with the experimental approaches. This review aims to provide a unified photophysical picture fundamental to understanding the outstanding light-harvesting and light-emitting properties of HPs. The hotbed of carrier and quasi-particle interactions uncovered in HPs underscores the critical role of ultrafast spectroscopy and fundamental photophysics studies in advancing perovskite optoelectronics.

Small to Large Polaron Behavior Induced by Controlled Interactions in Perovskite Quantum Dot Solids

“…Rational application of these materials must be underpinned by a detailed understanding of the nature and dynamics of the principal excitations and how they are connected to the material structure. In OIHPs, polarons are the essential photoexcitation that governs their unique optoelectronic properties, such as long (hot) carrier lifetime and moderate carrier mobility. , These are frequently discussed in terms of Fröhlich polarons, in which the charge carriers are dressed with nuclear polarization that arises via electron–phonon couplings and the ferroelectric properties of OIHPs. − Evidence of polaronic species in OIHPs spanning a wide range of dimensionalities and chemical compositions has been provided by time-resolved X-ray, electron diffraction, and terahertz spectroscopies which track time-dependent nuclear displacements during the polaron formation. − Complementary insights into the underlying electron–phonon couplings that drive polaron formation have been extracted from oscillatory components in the temporal profiles of pump–probe and multidimensional electronic spectroscopies. − …”

Enhancing Two-Dimensional Electronic Spectroscopy for Layered Halide Perovskites

“…Its versatility allows for the investigation of a diverse range of molecular systems, including small molecules, complex biomolecules, and light-harvesting materials, − exploring various phenomena such as energy transfer, electron transfer, and chemical reactions. Additionally, 2DES can provide valuable insights into interesting phenomena in semiconductors, − such as layered lead halide perovskites. , …”

Nanoscale 0D/1D Heterojunction of MAPbBr3/COF Toward Efficient LED-Driven S–S Coupling Reactions

“…However, organic–inorganic hybrid perovskites have the potential to urgently address these challenges among all the incumbent semiconductor candidates due to their advantages such as tailorable quantum confinement sizes, easily tunable light harvesting regions (band structures), high separation efficiency of photogenerated carriers, excellent photoelectronic conversion efficiency, high carrier mobility, long carrier lifetimes, and diffusion lengths. − Generally, ABX 3 is the abbreviated chemical formula of halide perovskites (HPs), where the A-site is usually occupied by monovalent metal cations (Cs + and Rb + ) or organic cations such as methylamine (CH 3 NH 2 + , MA + ), formamidine (HC­(CH 2 ) 2 + , FA + ), and phenethylamine (C 6 H 5 C 2 H 4 NH 3 + , PEA + ). The B-site is typically occupied by the metal cation from main groups IVA and VA (Pb 2+ and Bi 3+ ), meanwhile the X-site is selected from group VIIA (Cl – , Br – , and I – ). − The well-matched direct band gap to solar spectrum and excellent separation efficiency of carriers make MAPbBr 3 (MAPB) superior to other candidates, and significant advancements have been achieved in the fields of light-emitting diodes, solar cells, and photocatalysts, among others. Furthermore, benefiting from the high photon quantum efficiency jointly enhanced by the size-induced quantum confinement effect and the corresponding energy band/level splitting on zero-dimensional (0D) quantum dots (QDs), MAPB QDs exhibit promising applications in photocatalyst-related fields. , In particular, QD photocatalysts for organic reactions are still in their infancy.…”