Laser-induced inter-ion migration and the effect of different long alkylammonium halide functionalization on CH3NH3Pb(BrxI1−x)3 colloidal nanoparticles

Adnan, Mohammad; Kanaujia, Pawan K.; Prakash, G. Vijaya

doi:10.1016/j.apsusc.2020.146789

Cited by 5 publications

(3 citation statements)

References 56 publications

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“…[128] Spatially resolved PL mapping at specified wavelengths could reveal defective regions by their weaker intensity, [129] whereas PL mapping with the spectrum distribution could hint at phase variation. [130,131] In addition, by combining confocal microscopy with PL spectroscopy, a visual distribution of radiative and nonradiative luminance could be obtained. Dark spots with PL quenching appeared as the operation time increased (Figure 5c); this phenomenon was associated with Al diffusion through 2,2′,2′′-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) into perovskite and migration of Br − ions to the Al electrode.…”

Section: Optical Characterizationsmentioning

confidence: 99%

Ion Migration in Perovskite Light‐Emitting Diodes: Mechanism, Characterizations, and Material and Device Engineering

et al. 2022

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sivation), [18,19] the record EQEs of PeLEDs have reached 12.3%, [20] 28.1%, [21] 23%, [22] and 22.2% [23] for blue, green, red, and infrared emission, respectively. Despite the remarkable progress in improving the performance of PeLEDs, the devices still suffer from poor operational stability and rapid decay over time. Although encapsulation of the devices can protect them against moisture and oxygen, [24] internal heat-or electric field-driven defect generation processes, which are often linked to ion migration, could cause severe degradation of electroluminescence.Ion motion in MHPs was initially observed in perovskite solar cells (PSCs) and manifested as an anomalous dielectric response at low frequency and hysteresis in the current-voltage curve. [25] Extensive studies have been performed to investigate the properties of the ions, [25,26] the ion distribution in PSCs under dark and illumination, [27] and the electronic-ionic coupling and its impact on device operation. [28] PSCs differ from PeLEDs in that the fabrication of PeLEDs typically involves the use of largely excess organic halide salts; a portion of these halides do not participate in the perovskite lattice but instead reside on the surfaces and grain boundaries, thus inducing additional mobile ions in the PeLEDs. [29][30][31] More importantly, the electric field across the very thin perovskite layer (typically tens of nanometers) in a PeLED is much stronger than the field in a PSC. Because of these factors and the effects of local heating, ion migration has a substantial effect on PeLEDs operation. Indeed, numerous recent studies have reported ion-induced degradation of PeLEDs. [31][32][33][34][35][36] Accordingly, many studies on understanding, characterizing, and preventing ion generation and migration in PeLEDs have been performed in the last few years.Herein, we perform a systematic review of the origin, movement mechanism, characterization, effects on device performance and stability, and management of ion migration in PeLEDs. As presented in Scheme 1, the review begins by introducing the origins of ionic defects by considering the structural, compositional, and processing characteristics of perovskite emissive layers. Then, the transport dynamics of ions are described with a focus on three factors: Migration activation energy, external stimulus (e.g., electric field and Joule heating), and pathways (i.e., bulk vs grain boundaries or surfaces). Third, the characterization approaches for probing ion migration in In recent years, perovskite light-emitting diodes (PeLEDs) have emerged as a promising new lighting technology with high external quantum efficiency, color purity, and wavelength tunability, as well as, low-temperature processability. However, the operational stability of PeLEDs is still insufficient for their commercialization. The generation and migration of ionic species in metal halide perovskites has been widely acknowledged as the primary factor causing the performance degradation of PeLEDs. Herein, this topic is systematically d...

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Section: Optical Characterizationsmentioning

confidence: 99%

Ion Migration in Perovskite Light‐Emitting Diodes: Mechanism, Characterizations, and Material and Device Engineering

et al. 2022

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“…Additionally, the transient metastable phases are short-lived and undergo continual evolution and development as intercalation time progresses, rendering comparison at this stage challenging. The PL QYs of individual 2D/3D systems are widely reported; for example, the QY of 3D perovskite C1PI is about 46% and those of mixed C1PBr x I 1– x or (C2) x (C1) 1–x PbBr 3 systems vary between 5 to 85%. − Also, for 2D/3D mixed systems, such as (BA) 2 (MA) n–1 Pb n I 3n+1 , the PL QYs vary between 1% to 25%, despite the fact that precise estimation of such transient metastable phases requires meticulous measurements …”

Section: Resultsmentioning

confidence: 99%

Real-Time Monitoring of Progressive Crystal Phase Transformations and Associated Multi-Phase Optical Exciton Dynamics in Mixed (2D/3D) Inorganic–Organic Hybrid Semiconductors

Kanaujia,

Adnan,

Dehury

et al. 2023

Chem. Mater.

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The unique crystal structure dimensionality, possibilities of a wide range of crystal phases, wide bandgap tunability, associated optical exciton characteristics, and eventual optoelectronic properties make inorganic–organic (IO) hybrid semiconductors fascinating optoelectronic materials. In this study, we investigate the digitized intercalation process of various organic moieties, resulting in a mixed IO hybrid system of type (R-NH3)2(R′-NH3)n–1PbnI3n+1 between (R-NH3)2PbI4 (2D, n = 1) to (R′-NH3)PbI3 (3D, n = ∞) and vice versa. By employing real-time photoluminescence (PL) monitoring, we observe progressive and dynamic structural deviations/evolution and elucidate the underlying mechanisms occurring during the intercalation process. The interplay of (i) cyclic, (ii) long alkyl chain, and (iii) small alkyl amine based organic moieties during the intercalation leads to the formation of either 2D ((R-NH3)2PbI4) or 3D (R′-NH3PbI3) IO hybrid networks and unveiling significant structural phase variations within the 2D and 3D crystal packings. Several metastable interdigitized structural conformations appear during the dynamic process, ranging from n = 1 (2D) to n = ∞ (3D). Although, such metastable intermediate phases have been reported individually in chemically synthesized mixed IO hybrid structures, but in this work, for the first time, we demonstrate the real-time dynamic variations in these mixed IO hybrid configurations. The results have convincingly unveiled such conversions, which are clearly revealed by the progressive shift of exciton energies from high to low energies or vice versa. This comprehensive study provides a deep insight into various scenarios applicable to the nature of multiphase crystal packings in the broad range of IO hybrid semiconductors.

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“…Such growth of phase transition/stability kinetics can be generally explained by kinetic models, including a widely accepted Johnson-Mehl-Avrami-Kolmogorov (JMAK) model (or Avrami model). 17,[30][31][32] With the assumption that multidynamic processes are involved during laser-induced exciton PL dynamics/ transformation, the JMAK expression for exciton PL peak intensities I(t) could be written as…”

Section: Articlementioning

confidence: 99%

Real-time dynamic evolution monitoring of laser-induced exciton phase flips in 2D hybrid semiconductor (C12H25NH3)2PbI4

Adnan

Dehury

Kanaujia

et al. 2020

Journal of Applied Physics

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Real-time monitoring of room-temperature exciton photoluminescence (PL) while irradiated with ultrafast laser excitations (UV and infrared) in long alkyl-chain based (C 12 H 25 NH 3 ) 2 PbI 4 inorganic-organic hybrid semiconductors is presented. These naturally self-assembled 2D hybrid structures show strong room-temperature Mott-type excitons confined within the lowest inorganic bandgap, which are highly sensitive to structural phase flips. Under both one-photon (E 1PA ≥ E g ) and two-photon (2E 2PA ≥ E g ) laser excitations, the exciton PL of unstable phase-II appears initially, and with prolonged laser exposure, the PL peak switches to a new stable blueshifted phase-I peak position. This exciton phase flip demonstrates different laser-induced structural deformations in inorganic quantum wells (PbI 6 extended network) associated with orthorhombic (phase-I) and monoclinic (phase-II) unit cells. One-photon absorption induced PL shows the various time dynamics of laser exposure depending on laser characteristics (continuous wave and ultrashort pulsed lasers), mostly influenced by localized heating, ablation effects, and third-order nonlinear effects such as saturation of linear absorption and exciton-exciton annihilation. However, in two-photon absorption induced PL, the near infrared laser excitation reveals the redshifted crumpled excitons from the deeper depth of the sample, which are induced by multiphoton absorption and avalanche ionization. A series of systematic linear and nonlinear steady-state and time-resolved PL studies are presented. A simplified kinetic model further provides an understanding of the real-time evolution of laser-induced excitons and their related phase flips. These laser-induced exciton phase flips and linear and nonlinear optical probing open a new avenue for novel functional properties and nonlinear absorption-based optoelectronic devices.

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Laser-induced inter-ion migration and the effect of different long alkylammonium halide functionalization on CH3NH3Pb(BrxI1−x)3 colloidal nanoparticles

Cited by 5 publications

References 56 publications

Ion Migration in Perovskite Light‐Emitting Diodes: Mechanism, Characterizations, and Material and Device Engineering

Ion Migration in Perovskite Light‐Emitting Diodes: Mechanism, Characterizations, and Material and Device Engineering

Real-Time Monitoring of Progressive Crystal Phase Transformations and Associated Multi-Phase Optical Exciton Dynamics in Mixed (2D/3D) Inorganic–Organic Hybrid Semiconductors

Real-time dynamic evolution monitoring of laser-induced exciton phase flips in 2D hybrid semiconductor (C12H25NH3)2PbI4

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