Recent Progress and Prospects on Metal Halide Perovskite Nanocrystals as Color Converters in the Fabrication of White Light-Emitting Diodes

Mohapatra, Ashutosh; Kar, Manav R.; Bhaumik, Saikat

doi:10.3389/femat.2022.891983

Cited by 8 publications

(4 citation statements)

References 97 publications

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“…In these types of perovskites, the positions of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are mostly dependent on the mutual interaction between the Pb and Br ions. [ 38 ] Here, the LUMO level is mostly defined by the Pb 6 p orbitals, while the HOMO level is constituted by the Pb 6 s orbitals and the Br n p ( n = 4,5,6) orbitals. [ 39 ] The reduction in the Pb–Br bond length makes the electrons on the Pb atoms more confined; this increased the energy and lifted the LUMO level, thereby increasing the effective bandgap.…”

Section: Resultsmentioning

confidence: 99%

Super‐Bright Green Perovskite Light‐Emitting Diodes Using Ionic Liquid Additives

et al. 2023

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size of the CsPbBr 3 film, as large crystallites reduce the probability of radiative recombination in the perovskite crystallites, resulting in poor light emission. [9] However, small crystallites have large crystallite boundaries and high surfacetrap density. Thus, passivating surface traps is an integral part of the fabrication of high-performance PeLEDs. [10,11] This passivation is performed mostly by using different kinds of organic or inorganic additives that simultaneously affect the film growth and passivate the perovskite surfaces as a capping ligand. [12][13][14] Another major issue with perovskite materials is their high ionic activity and bias-dependent ion migration. [13] Severe ion migration can create numerous ionic vacancies, which subsequently results in lattice collapse. Ion migration is also responsible for the spectral shift in the wavelength emitted by PeLEDs, particularly for mixed-anion and mixed-cation PeLEDs. [4,5] This can be prevented by confining the ions in small crystallites using capping ligands. [15][16][17] However, most of these long-chain ligands are electrically insulating in nature which leaves a nonconducting sheath around the perovskite crystallites and thus hindering the electrical connection between the perovskite emissive and charge transport layers. [18] In addition, a high EQE was achieved only at low current densities in the range of 1-100 mA cm −2 . [13] At higher current densities, different phenomena, such as Auger recombination, imbalance in charge injection, and Joule heating, collectively lead to an efficiency roll-off. Thus, the working current density for stable PeLED operation remains low, limiting their luminance to less than 1 × 10 5 cd m −2 , whereas organic LEDs (OLED) and quantum dot LEDs can achieve more than 6 × 10 5 cd m −2 luminance. [19] Overpowering this roll-off and improving the working current density are important for achieving a high luminance with a sufficiently high EQE in PeLEDs for commercial applications. Additionally, delivering a high injection current that overcomes the lasing threshold would help the realization of electrically pumped perovskite laser diodes in the future. [20] However, while the EQEs of PeLEDs, especially green-emitting ones, have rapidly increased in recent years, there is still much to be explored for brightness enhancement.In this study, we have demonstrated a high-luminance green PeLED by controlling the CsPbBr 3 film morphology and its band energy levels using a room-temperature ionic liquid (IL) additive. ILs have been explored in perovskite solar cells before, Halide perovskites have potential for use in next-generation low-cost, highefficiency, and highly color-pure light-emitting diodes (LED) that can be used in various applications, such as flat and flexible displays and solid-state lighting. However, they still lag behind other mature technologies, such as organic LEDs and inorganic LEDs, in terms of performance, particularly brightness. This lag is partly due to the insulating nature of the long-chain organ...

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Section: Resultsmentioning

confidence: 99%

Super‐Bright Green Perovskite Light‐Emitting Diodes Using Ionic Liquid Additives

et al. 2023

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“…In comparison, MAPbBr 3 exhibit better solution processability and is also cost-effective. In spite of this, MAPbBr 3 NCs are prone to degradation due to external factors such as light, heat, moisture and oxygen, which leads us to compromise their optical and electrical properties [2]. Another associated factor is the large surface area of these NCs.…”

Section: Introductionmentioning

confidence: 99%

In-situ synthesis of quaternary alkylammonium ligand capped organic-inorganic hybrid halide perovskite for high pure green luminescence in display application

Rao,

Paramasivam,

Selvakumar

et al. 2024

Mater. Res. Express

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This study delves into the intricate dynamics of ligand engineering for the synthesis of Methyl Ammonium Lead Bromide (MAPbBr3) nanocrystals (NCs), which exhibit immense potential in optoelectronic and photovoltaic applications. Our focus centres on the role of the quaternary ammonium molecule CTAB as a ligand in stabilizing MAPbBr3 NCs. This also addresses the challenges related to the stability and surface defects of NCs that hinder their commercial viability. Employing a modified ligand-assisted reprecipitation technique (LARP) with a dual solvent system, we optimized the CTAB concentration to 0.05 mmol, resulting in MAPbBr3 NCs with an impressive 88% quantum yield. XPS and FTIR analyses confirm the presence and binding of CTAB on the NC surface. The MAPbBr3-CTAB NCs exhibit higher exciton-phonon binding energy, enhancing their optical properties. Despite an unfavourable geometric fit, CTAB is effective in surface defect passivation due to its binding, solvation, and desorption energy during the dynamic binding process. 2D-DOSY NMR reveals approximately 66% CTAB bound to the NC surface. A comparative study involving MAPbBr3-OA, OLA, and MAPbBr3-CTAB deposited on LEDs demonstrates the superior performance of the latter, achieving a luminous efficiency of 42.18 lm/W at 1.2 mL deposition. These findings highlight the efficacy of CTAB in achieving high-purity green luminescence, aligning with BT.2020 display colour standards and paving the way for advanced optoelectronic applications. The successful synthesis and improved performance of MAPbBr3-CTAB NCs underscore their potential as a promising material for future optoelectronic and photovoltaic technologies.

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“…6,7 In recent years, researchers have been exploring the use of PeNCs in LEDs. [8][9][10][11] One of the key challenges in this area is achieving high external quantum efficiency (EQE), which is a measure of how efficiently the optoelectronic device converts electrical energy into light. One approach for improving the EQE of halide perovskite LEDs has been the use of PeNCs as an active layer instead of bulk thin lms.…”

Section: Introductionmentioning

confidence: 99%

Impact of core–shell perovskite nanocrystals for LED applications: successes, challenges, and prospects

et al. 2023

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Recent Progress and Prospects on Metal Halide Perovskite Nanocrystals as Color Converters in the Fabrication of White Light-Emitting Diodes

Cited by 8 publications

References 97 publications

Super‐Bright Green Perovskite Light‐Emitting Diodes Using Ionic Liquid Additives

Super‐Bright Green Perovskite Light‐Emitting Diodes Using Ionic Liquid Additives

In-situ synthesis of quaternary alkylammonium ligand capped organic-inorganic hybrid halide perovskite for high pure green luminescence in display application

Impact of core–shell perovskite nanocrystals for LED applications: successes, challenges, and prospects

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