Direct Observation of Charge Collection at Nanometer-Scale Iodide-Rich Perovskites during Halide Exchange Reaction on CH₃NH₃PbBr₃

Organolead halide perovskites MAPbX₃ (MA = CH₃NH₃⁺, X = Cl^–, Br^–, or I^–) are known to undergo reversible halide exchange reactions, enabling bandgap tuning over the visible light region. Using single-particle photoluminescence (PL) imaging for in situ observation, we have studied the structure-dependent charge dynamics during halide exchange with iodide ions on an MAPbBr₃ crystal. In particular, we optically detected nanometer-scale iodide-rich domains (i.e., MAPbBrI₂) and found that their lifetimes of several tens of milliseconds are limited by reaction with diffusing vacancies. Furthermore, it was discovered that these domains effectively collect the charge carriers from the bulk crystal, thus resulting in amplified spontaneous emission (ASE) under continuous-wave laser irradiation. Our findings will provide direction for development of perovskite heterostructures with enhanced charge utilization

Surface Charge Trapping in Organolead Halide Perovskites Explored by Single-Particle Photoluminescence Imaging

Organometal halide perovskites have attracted considerable attention because of their striking electrical and optical properties that are desirable for application in solar cells and optoelectronic devices; however, the structure-related dynamics of photogenerated charges are almost always masked by ensemble averaging in conventional spectroscopic methods, making it difficult to clarify the underlying mechanism. Here we investigate the photoluminescence characteristics of CH₃NH₃PbBr₃ perovskite nanoparticles using single-particle spectroscopy combined with electron microscopy. The in situ analysis of light and Lewis-base-induced surface passivation revealed that the photoluminescence quenching and blinking phenomena of single CH₃NH₃PbBr₃ nanoparticles are most probably caused by charge trapping at surface states, where the number of effective trapping sites was estimated to be 1–4 per particle

Direct Observation of Charge Collection at Nanometer-Scale Iodide-Rich Perovskites during Halide Exchange Reaction on CH₃NH₃PbBr₃

Organolead halide perovskites MAPbX₃ (MA = CH₃NH₃⁺, X = Cl^–, Br^–, or I^–) are known to undergo reversible halide exchange reactions, enabling bandgap tuning over the visible light region. Using single-particle photoluminescence (PL) imaging for in situ observation, we have studied the structure-dependent charge dynamics during halide exchange with iodide ions on an MAPbBr₃ crystal. In particular, we optically detected nanometer-scale iodide-rich domains (i.e., MAPbBrI₂) and found that their lifetimes of several tens of milliseconds are limited by reaction with diffusing vacancies. Furthermore, it was discovered that these domains effectively collect the charge carriers from the bulk crystal, thus resulting in amplified spontaneous emission (ASE) under continuous-wave laser irradiation. Our findings will provide direction for development of perovskite heterostructures with enhanced charge utilization

Direct Observation of Charge Collection at Nanometer-Scale Iodide-Rich Perovskites during Halide Exchange Reaction on CH₃NH₃PbBr₃

Organolead halide perovskites MAPbX₃ (MA = CH₃NH₃⁺, X = Cl^–, Br^–, or I^–) are known to undergo reversible halide exchange reactions, enabling bandgap tuning over the visible light region. Using single-particle photoluminescence (PL) imaging for in situ observation, we have studied the structure-dependent charge dynamics during halide exchange with iodide ions on an MAPbBr₃ crystal. In particular, we optically detected nanometer-scale iodide-rich domains (i.e., MAPbBrI₂) and found that their lifetimes of several tens of milliseconds are limited by reaction with diffusing vacancies. Furthermore, it was discovered that these domains effectively collect the charge carriers from the bulk crystal, thus resulting in amplified spontaneous emission (ASE) under continuous-wave laser irradiation. Our findings will provide direction for development of perovskite heterostructures with enhanced charge utilization

Surface Charge Trapping in Organolead Halide Perovskites Explored by Single-Particle Photoluminescence Imaging

Organometal halide perovskites have attracted considerable attention because of their striking electrical and optical properties that are desirable for application in solar cells and optoelectronic devices; however, the structure-related dynamics of photogenerated charges are almost always masked by ensemble averaging in conventional spectroscopic methods, making it difficult to clarify the underlying mechanism. Here we investigate the photoluminescence characteristics of CH₃NH₃PbBr₃ perovskite nanoparticles using single-particle spectroscopy combined with electron microscopy. The in situ analysis of light and Lewis-base-induced surface passivation revealed that the photoluminescence quenching and blinking phenomena of single CH₃NH₃PbBr₃ nanoparticles are most probably caused by charge trapping at surface states, where the number of effective trapping sites was estimated to be 1–4 per particle

Surface Charge Trapping in Organolead Halide Perovskites Explored by Single-Particle Photoluminescence Imaging

Organometal halide perovskites have attracted considerable attention because of their striking electrical and optical properties that are desirable for application in solar cells and optoelectronic devices; however, the structure-related dynamics of photogenerated charges are almost always masked by ensemble averaging in conventional spectroscopic methods, making it difficult to clarify the underlying mechanism. Here we investigate the photoluminescence characteristics of CH₃NH₃PbBr₃ perovskite nanoparticles using single-particle spectroscopy combined with electron microscopy. The in situ analysis of light and Lewis-base-induced surface passivation revealed that the photoluminescence quenching and blinking phenomena of single CH₃NH₃PbBr₃ nanoparticles are most probably caused by charge trapping at surface states, where the number of effective trapping sites was estimated to be 1–4 per particle

Determination of the fine structure of a halide perovskite using THz spectroscopy

In a crystalline solid, many types of disorders exist. Revealing the localized structures induced by disorder is one of the central issues of crystallography. Retrieving information about disorder from the scattering patterns of X-ray and/or neutron diffractions is still facing vital challenges. New experimental observations, whenever available, are greeted to shed additional light on this problem. We have in one previous work demonstrated a ubiquitous capability of terahertz (THz) spectroscopy to detect the fingerprint vibrational peaks of correlated molecular arrangements at the nano-scale level in an occupation disorder system.[1] We will, in this work, employ THz spectroscopy to study the fine structure of the halide perovskite systems where the short-range order of the disordered methylammonium (MA) molecules remains an open question.Published versio