Efficient Visible Quasi‐2D Perovskite Light‐Emitting Diodes

Organo-metal halide perovskites are a promising platform for optoelectronic applications in view of their excellent charge transport and bandgap tunability. However, their low photoluminescence quantum efficiencies, especially in low excitation regimes, limit their efficiency for light emission. Consequently, perovskite light emitting devices are operated under high injection, a regime under which the materials have so far been unstable. Here we show that, by concentrating photoexcited states into a small subpopulation of radiative domains, one can achieve a high quantum yield even at low excitation intensities. We tailor the composition of quasi-2D perovskites to direct energy transfer into the lowest-bandgap

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“…However, these devices show low efficiency (below 1%) and limited photo-stability ( Table 1) 23,24 .…”

mentioning

confidence: 99%

Tailoring the Energy Landscape in Quasi-2D Halide Perovskites Enables Efficient Green-Light Emission

et al. 2017

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“…Practically, a mixture of small and large organic cations is applied to the perovskite structure. In most cases, quasi 2D "Ruddlesden-Popper (RP)" phase PNCs were reported, [56,[63][64][65][66] which can be treated as a mixture of multilayered PNCs while nanosized 3D PNCs were reported elsewhere. [55] Here, the selection and incorporation concentration of bulky organic cations, the controlling of spin-coating process as well as the antisolvent play an important role in the formation mechanism.…”

Section: The Roadmap Of Perovskite Nanocrystalsmentioning

confidence: 99%

“…As mentioned above, the quasi 2D PNC structure can be denoted as L 2 A n−1 B n X 3n+1 . Plenty of investigations have been conducted on the choices of bulky cation L, including PEA, [56,63,64,[89][90][91][92] BA, [55,88,[93][94][95] ethylammonium (EA), [96] phenylmethylamine (PMA), [97] phenylbutylammonium (PBA), [98,99] naphthylmethylamine (NMA) [65,100] and 2-Phenoxyethylamine (POEA). [101] Similar to the pure 2D structure, with the space dimension reduced to nanosized 3D or quasi 2D, the PNCs exhibit strong excitonic behavior.…”

Section: Organic Ammonium Assisted In Situ Fabricationmentioning

confidence: 99%

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In Situ Fabricated Perovskite Nanocrystals: A Revolution in Optical Materials

Chang

Bai

Zhong

2018

Advanced Optical Materials

192

127

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in bulk halide perovskites, long carrier diffusion length, and an absorption range covering the visible solar spectrum, collectively enable the high performance of photo electricity conversion. Compared to the bulk materials, perovskite nanocrystals or quantum dots (usually denoted as PNCs or PQDs) show obvious excitonic features with enhanced photoluminescence (PL) properties due to the well-known size-dependent quantum confinement effects. [14][15][16][17] The combination of color saturated emissions, super high quantum yield (QY), as well as easy processing inspired the intensive exploration of PNCs as light emitters, which is now under spotlights in the field of optical materials.The first perspective aim of PNCs is to alternate the state-of-the-art CdSe or InP quantum dots (QDs) as new generation luminescence materials. [18,19] As shown in Figure 1, these QD materials have been well demonstrated to be potential functional components for photonic and optoelectronic applications, and are currently on the way to industrialization. [20][21][22][23] Specifically, QDs can be employed as fluorescence labels, [24] laser gain media, [25] LED phosphors, [26] and down-shifting films for LCD backlights. [27,28] They can also be processed into thin film for optoelectronic devices including solar cells, [29] photodetectors, [30,31] transistors [32] and LEDs. [33] The PNCs outcompete these conventional QDs in terms of narrower full width at half maximum (FWHM) and low fabrication cost, but most importantly, the ease of in situ preparation. [34,35] Herein, this progress report highlight the developments of in situ fabricated PNCs.Colloidal semiconductor QDs are typically synthesized ex situ in flasks by hot injection method, stabilized by surface ligands. [36][37][38][39] To incorporate such solution based materials into applications usually requires purification, redispersion and surface engineering. For instance, ligand exchange is often employed to disperse QDs into aimed solvent, inducing defects that inevitably derogating the PLQYs. [40] Moreover, the organic ligands themselves also suffer from the risk of disabsorbing, reducing the stability of the QDs and thus the final devices. [41] Because halide perovskite are ionic compounds that can be well dissolved into polar solvents, PNCs can be fabricated through either ex situ routes in flask or in situ strategies on substrates. The in situ fabricated PNCs are adaptable to devices integration due to their scalable and low-cost manufacturing. In this regard, more and more efforts have been made in terms of the controlling synthesis, physical properties and device applications of PNC materials.After over 30 years of development, colloidal quantum dots have now become mature luminescent materials in photonic and optoelectronic operations and start to hit the market. The emerging perovskite nanocrystals are expected to promote large-scale commercialization due to their superior optical properties as well as low cost and easy fabrication. This progress report is focused on the...

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“…These works demonstrated that pure perovskites can emit bright EL with very high color purity at RT. Many subsequent studies used a variety of experimental approaches to improve the luminescence efficiencies of PeLEDs (8)(9)(10)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60)(61)(62)(63)(64)(65)(66).…”

Section: Renaissance Of Perovskite Emitters: Bulk Polycrystalline Filmentioning

confidence: 99%

Metal halide perovskite light emitters

Kim

Cho

Lee

2016

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

499

441

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Twenty years after layer-type metal halide perovskites were successfully developed, 3D metal halide perovskites (shortly, perovskites) were recently rediscovered and are attracting multidisciplinary interest from physicists, chemists, and material engineers. Perovskites have a crystal structure composed of five atoms per unit cell (ABX 3 ) with cation A positioned at a corner, metal cation B at the center, and halide anion X at the center of six planes and unique optoelectronic properties determined by the crystal structure. Because of very narrow spectra (full width at half-maximum ≤20 nm), which are insensitive to the crystallite/grain/particle dimension and wide wavelength range (400 nm ≤ λ ≤ 780 nm), perovskites are expected to be promising high-color purity light emitters that overcome inherent problems of conventional organic and inorganic quantum dot emitters. Within the last 2 y, perovskites have already demonstrated their great potential in light-emitting diodes by showing high electroluminescence efficiency comparable to those of organic and quantum dot light-emitting diodes. This article reviews the progress of perovskite emitters in two directions of bulk perovskite polycrystalline films and perovskite nanoparticles, describes current challenges, and suggests future research directions for researchers to encourage them to collaborate and to make a synergetic effect in this rapidly emerging multidisciplinary field.As human civilization went through the information revolution, display technology has been designated as a core technology to increase convenience in daily human life. In an information society, the desire of humans to see the materials more vividly in displays has significantly increased. In this aspect, major trend of the display technology is changing from high resolution and high efficiency to high color purity for realizing vivid natural colors (Fig. 1). Therefore, research on new emitting materials that can emit light with narrow full width at halfmaximum (FWHM) have been attempted. Inorganic quantum dot (QD) emitters with narrow spectra (FWHM ∼30 nm) have been significantly studied following organic emitters (FWHM >40 nm); however, size-sensitive color purity, difficult size uniformity control, and expensive material costs of inorganic QD emitters retard the progress for wide use in industry. Therefore, new emitters with size-insensitively high color purity (FWHM <20 nm) and low material cost should be developed. Among many candidates, metal halide perovskites (hereafter, "perovskites") have gained great attentions and shown the possibility for future high-color purity emitters.The first perovskites were layer-type thin films (A 2 MX 4 ) (A = organic cation; M = divalent metal; X = Cl, Br, I) (1-6).They were expected to be novel hybrid materials that had both advantages of organic materials (e.g., solution processability and low material costs) and inorganic materials (e.g., high charge carrier mobility) (7). Especially, perovskites with high color purity, easy wavelength tuning, and ...

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Efficient Visible Quasi‐2D Perovskite Light‐Emitting Diodes

Cited by 597 publications

References 27 publications

Tailoring the Energy Landscape in Quasi-2D Halide Perovskites Enables Efficient Green-Light Emission

Tailoring the Energy Landscape in Quasi-2D Halide Perovskites Enables Efficient Green-Light Emission

In Situ Fabricated Perovskite Nanocrystals: A Revolution in Optical Materials

Metal halide perovskite light emitters

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