Highly Efficient Perovskite Light-Emitting Diodes Incorporating Full Film Coverage and Bipolar Charge Injection

Chen, Ping; Xiong, Ziyang; Wu, Xiaoyan; Shao, M.; Ma, Xing‐Juan; Xiong, Zuhong; Gao, Chun‐Hong

doi:10.1021/acs.jpclett.7b00368

Cited by 101 publications

(73 citation statements)

References 50 publications

(145 reference statements)

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“…In MHP NCs, electron‐hole pairs can be easily dissociated in film states due to the close proximity of the NCs; this process decreases the LE. Inspired by the progress of OLEDs, we suggest that dopant‐in‐host (MHP PC or NC‐in‐organic) systems have potential to improve the EL efficiency of PeLEDs because these systems may further reduce the grain size, passivate surface defects in grain boundaries, and prevent dissociation of electron‐hole pairs. Inspired by the progress of QD LEDs, core–shell or gradient–alloy (MHP NC–inorganic) system may also further confine the electron‐hole pairs in their core perovskites and improve the EL efficiency.…”

Section: Discussionmentioning

confidence: 99%

“…Mixing two organic molecules (PEO with polyvinylpyrrolidone (PVP) or PVK with 1,3,5‐tris(1‐phenyl‐1 H ‐benzimidazol‐2‐yl)benzene (TPBI)) can further improve the uniformity of MHP PC films, facilitate charge injection from the HIL/EML and EML/EIL interfaces due to the in situ‐formed p–i–n junction in the EML or efficient charge‐transport properties of PVK (hole mobility ≈ 4.8 × 10 −9 cm 2 V −1 s −1 ) and TPBI (electron mobility ≈ 5.14 × 10 −5 cm 2 V −1 s −1 ), and thus achieve an efficient EL in PeLEDs (EQE ≈ 5.7%, power efficiency PE ≈ 14.1 lm W −1 , L ≈ 593 178 cd m −2 for PeLEDs based on PEO:PVP:CsPbBr 3 ; EQE ≈ 2.28%, CE ≈ 9.45 cd A −1 , L ≈ 7263 cd m −2 for PeLEDs based on PEO:PVP:MAPbBr 3 ).…”

Section: Solution‐processed Polycrystalline Bulk Films and Light‐emitmentioning

confidence: 99%

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Metal Halide Perovskites: From Crystal Formations to Light‐Emitting‐Diode Applications

Kim

et al. 2018

Small Methods

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Metal halide perovskites (MHPs) are promising light emitters because they have high color purity, high charge‐carrier mobility, comparable energy levels with organic semiconductors, and the possibility of diverse crystal forms and various crystal formation methods. Since the first report of MHP light‐emitting diodes (PeLEDs) in 2014, many researchers have devoted efforts to increase the luminescence efficiencies of MHPs in various crystal forms, and achieved dramatically improved photoluminescence quantum efficiency of >90% in MHP emitters and external quantum efficiency of ≈14.36% in PeLEDs. Here, the recent progress regarding PeLEDs is reviewed by categorizing MHPs into three types: polycrystalline bulk films, colloidal nanocrystals, and single crystals. The main focus is on photophysical properties, crystallization methods, and mechanisms of various crystal formation, and applications to PeLEDs. Future research directions are also suggested and an outlook for MHP emitters and PeLEDs is given.

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Section: Discussionmentioning

confidence: 99%

Section: Solution‐processed Polycrystalline Bulk Films and Light‐emitmentioning

confidence: 99%

Metal Halide Perovskites: From Crystal Formations to Light‐Emitting‐Diode Applications

Kim

et al. 2018

Small Methods

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“…[68] It is also possible to blend the polymeric charge transporting materials such as polyvinyl carbazole (PVK) [134,135] into the perovskite films to control the film morphology and facilitate the charge transport.…”

Section: Electroluminescencementioning

confidence: 99%

In Situ Fabricated Perovskite Nanocrystals: A Revolution in Optical Materials

Chang

Bai

Zhong

2018

Advanced Optical Materials

188

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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“…Radiative recombination and hence PLQY can be substantially enhanced through spatial confinement of charges, which can be obtained in passivated perovskite nanostructures, such as colloidal nanocrystals . Another way of obtaining nanostructured perovskites is the use of a scaffold, which can be a metal oxide, a polymer, or even a small molecular weight compound (small molecules) that can be blended and solution‐processed with the perovskite precursors . In this way, the crystal/grain growth of the perovskite is limited by of the dielectric scaffold, and highly luminescent perovskite composite films can be readily prepared.…”

Section: Introductionmentioning

confidence: 99%

“…[12][13][14] Another way of obtaining nanostructured perovskites is the use of as caffold, which can be am etal oxide, [15,16] ap olymer, [17][18][19][20][21][22] or even a small molecular weightc ompound (smallm olecules) that can be blended and solution-processed with the perovskite precursors. [23,24] In this way,t he crystal/graing rowth of the perovskite is limited by of the dielectric scaffold, and highly luminescent perovskite composite films can be readily prepared. Onei mportant condition that must be met to ensure ah igh PLQY is the passivation of perovskite crystals.…”

Section: Introductionmentioning

confidence: 99%

High Photoluminescence Quantum Yields in Organic Semiconductor–Perovskite Composite Thin Films

et al. 2017

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One of the obstacles towards efficient radiative recombination in hybrid perovskites is a low exciton binding energy, typically in the orders of tens of meV. It has been shown that the use of electron‐donor additives can lead to a substantial reduction of the non‐radiative recombination in perovskite films. Herein, the approach using small molecules with semiconducting properties, which are candidates to be implemented in future optoelectronic devices, is presented. In particular, highly luminescent perovskite–organic semiconductor composite thin films have been developed, which can be processed from solution in a simple coating step. By tuning the relative concentration of methylammonium lead bromide (MAPbBr3) and 9,9spirobifluoren‐2‐yl‐diphenyl‐phosphine oxide (SPPO1), it is possible to achieve photoluminescent quantum yields (PLQYs) as high as 85 %. This is attributed to the dual functions of SPPO1 that limit the grain growth while passivating the perovskite surface. The electroluminescence of these materials was investigated by fabricating multilayer LEDs, where charge injection and transport was found to be severely hindered for the perovskite/SPPO1 material. This was alleviated by partially substituting SPPO1 with a hole‐transporting material, 1,3‐bis(N‐carbazolyl)benzene (mCP), leading to bright electroluminescence. The potential of combining perovskite and organic semiconductors to prepare materials with improved properties opens new avenues for the preparation of simple lightemitting devices using perovskites as the emitter.

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Highly Efficient Perovskite Light-Emitting Diodes Incorporating Full Film Coverage and Bipolar Charge Injection

Cited by 101 publications

References 50 publications

Metal Halide Perovskites: From Crystal Formations to Light‐Emitting‐Diode Applications

Metal Halide Perovskites: From Crystal Formations to Light‐Emitting‐Diode Applications

In Situ Fabricated Perovskite Nanocrystals: A Revolution in Optical Materials

High Photoluminescence Quantum Yields in Organic Semiconductor–Perovskite Composite Thin Films

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