Perovskite Light‐Emitting Diodes: Perovskite Quantum Dots with Ultralow Trap Density by Acid Etching‐Driven Ligand Exchange for High Luminance and Stable Pure‐Blue Light‐Emitting Diodes (Adv. Mater. 15/2021)

Bi, Chenghao; Yao, Zhiwei; Sun, Xiankai; Wei, Xianhua; Wang, Junxi; Tian, Jianjun

doi:10.1002/adma.202170119

Cited by 56 publications

(68 citation statements)

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“…As illustrated in Figure 11e, the introduction of HBr first etches imperfect [PbBr 6 ] 4– octahedrons to remove surface defects and excessive carboxylate ligands, followed by didodecylamine and phenethylamine post‐treatment to in situ exchange with native long‐chain ligands and coordinate with residual surface defects. Undergoing such an acid etching‐driven ligand exchange process, PQLEDs adopting blue‐emitting small‐size CsPbBr 3 QDs (≈4 nm) with an ultralow trap density exhibited a high EQE of 4.7% with a remarkable luminance of 3850 cd m –2 , and excellent operational stability with a T 50 of 12 h. [ 126 ] Apart from iodide and bromide sources, F surface passivation could be achieved by a solution‐phase ligand exchange process of CsPbBr 3 QDs using di‐dodecyl dimethyl ammonium fluoride (DDAF). Substituting the outer Br anion by F anion could form fluorine‐rich surfaces with a wider energy gap than the inner PQD core to suppress carrier trapping and ensure efficient charge injection.…”

Section: Photovoltaics and Optoelectronic Applicationsmentioning

confidence: 99%

Surface Chemistry Engineering of Perovskite Quantum Dots: Strategies, Applications, and Perspectives

et al. 2021

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The presence of surface ligands not only plays a key role in keeping the colloidal integrity and non‐defective surface of metal halide perovskite quantum dots (PQDs), but also serves as a knob to tune their optoelectronic properties for a variety of exciting applications including solar cells and light‐emitting diodes. However, these indispensable surface ligands may also deteriorate the stability and key properties of PQDs due to their highly dynamic binding and insulating nature. To address these issues, a number of innovative surface chemistry engineering approaches have been developed in the past few years. Based on an in‐depth fundamental understanding of the surface atomistic structure and surface defect formation mechanism in the tiny nanoparticles, a critical overview focusing on the surface chemistry engineering of PQDs including advanced colloidal synthesis, in‐situ surface passivation, and solution‐phase/solid‐state ligand exchange is presented, after which their unprecedented achievements in photovoltaics and other optoelectronics are presented. The practical hurdles and future directions are critically discussed to inspire more rational design of PQD surface chemistry toward practical applications.

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Section: Photovoltaics and Optoelectronic Applicationsmentioning

confidence: 99%

Surface Chemistry Engineering of Perovskite Quantum Dots: Strategies, Applications, and Perspectives

et al. 2021

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“…The increased contact angle indicates a reduction in surface energy due to effective passivation of unsaturated atoms by hydrophobic ligands. [ 32,34 ]…”

Section: Resultsmentioning

confidence: 99%

“…To overcome these problems, various approaches have been attempted, including amorphous CsPbBr x shelling, [ 31 ] the addition of excess Br using ZnBr 2 as the source, [ 29 ] Sb 3+ doping, [ 32 ] and acid etching‐driven ligand exchange. [ 34 ] However, few studies have been conducted on the application of blue LEDs incorporating highly stable CsPbBr 3 QDs. [ 9,34 ] A quite different approach involves CsPbBr 3 NCs being embedded in a Cs 4 PbBr 6 matrix with a crystal size of several hundred nanometers or more, resulting in improved PLQY and stability.…”

Section: Introductionmentioning

confidence: 99%

“…[ 34 ] However, few studies have been conducted on the application of blue LEDs incorporating highly stable CsPbBr 3 QDs. [ 9,34 ] A quite different approach involves CsPbBr 3 NCs being embedded in a Cs 4 PbBr 6 matrix with a crystal size of several hundred nanometers or more, resulting in improved PLQY and stability. [ 35–38 ] However, the literature reports in this area have been focused only on green emission, and Cs 4 PbBr 6 /CsPbBr 3 embedded structures are not suitable for electroluminescent devices because a 0D Cs 4 PbBr 6 phase has a wide bandgap of 3.95 eV and is insulating.…”

Section: Introductionmentioning

confidence: 99%

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Highly Emissive Blue Quantum Dots with Superior Thermal Stability via In Situ Surface Reconstruction of Mixed CsPbBr₃–Cs₄PbBr₆ Nanocrystals

Kim

Lee

et al. 2021

Advanced Science

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Although metal halide perovskites are candidate high-performance light-emitting diode (LED) materials, blue perovskite LEDs are problematic: mixed-halide materials are susceptible to phase segregation and bromide-based perovskite quantum dots (QDs) have low stability. Herein, a novel strategy for highly efficient, stable cesium lead bromide (CsPbBr 3 ) QDs via in situ surface reconstruction of CsPbBr 3 -Cs 4 PbBr 6 nanocrystals (NCs) is reported. By controlling precursor reactivity, the ratio of CsPbBr 3 to Cs 4 PbBr 6 NCs is successfully modulated. A high photoluminescence quantum yield (PLQY) of >90% at 470 nm is obtained because octahedron CsPbBr 3 QD surface defects are removed by the Cs 4 PbBr 6 NCs. The defect-engineered QDs exhibit high colloidal stability, retaining >90% of their initial PLQY after >120 days of ambient storage. Furthermore, thermal stability is demonstrated by a lack of heat-induced aggregation at 120 °C. Blue LEDs fabricated from CsPbBr 3 QDs with reconstructed surfaces exhibit a maximum external quantum efficiency of 4.65% at 480 nm and excellent spectral stability.

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“…[ 23c ] Table 2 lists a number of short‐chain ligands that have been utilized for making highly efficient PQD devices. [ 97–118 ] It can be seen from the table that the carboxylic acids (acetic, caproic, octanoic, and benzoic acid), amines (propylamine, butylamine, hexylamine, octylamine, and phenylamine), and their derivatives are typically used as surface capping ligands of PQDs. In addition, iodide and bromide salts have been proven advantageous for charge transport in active layer.…”

Section: Scale‐up Of Pqd Solar Cellsmentioning

confidence: 99%

Colloidal Quantum Dot Solar Cells: Progressive Deposition Techniques and Future Prospects on Large‐Area Fabrication

et al. 2022

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large-area fabrication without compromising the power conversion efficiency (PCE) always comes with new and unexpected challenges even for well-studied and well-optimized laboratory-scale PV technologies. For instance, non-concentrated monocrystalline silicon solar cells have reached a record 26.1% PCE, [1] but the efficiencies of most recent commercial panels are typically only up to about 22% (e.g., SunPower's Maxeon 3 panels: 22.8%, LG's Neon R: 22%, Panasonic's EverVolt: 21.7%). [2] Apart from the technical challenges, cost is the main driving factor for industry when it comes to production of modules or panels by scaling up laboratory-scale research cells. Low-cost PV technologies with performance comparable to existing industrial PV technologies may help in achieving the desired cost target, and perovskite solar cell (PSC) technology is the most suitable candidate in the current scenario. [3] The last decade saw a monumental rise in PSC technology. The perovskite absorber naturally possesses most of the desired properties for highly efficient solar cells, such as long carrier diffusion length, high carrier mobility, high light absorption coefficient, and excellent defect-tolerance. [4] Both in terms of laboratory-scale research cells and large-area panels, PSCs have seen a steep rise in PCE, reaching 25.8% for research cells, [1] and 17.9% for large-area modules with size of 802 cm 2 . [2] Further, PSC processing is relatively simple and Colloidally grown nanosized semiconductors yield extremely high-quality optoelectronic materials. Many examples have pointed to near perfect photoluminescence quantum yields, allowing for technology-leading materials such as high purity color centers in display technology. Furthermore, because of high chemical yield, and improved understanding of the surfaces, these materials, particularly colloidal quantum dots (QDs) can also be ideal candidates for other optoelectronic applications. Given the urgent necessity toward carbon neutrality, electricity from solar photovoltaics will play a large role in the power generation sector. QDs are developed and shown dramatic improvements over the past 15 years as photoactive materials in photovoltaics with various innovative deposition properties which can lead to exceptionally low-cost and high-performance devices. Once the key issues related to charge transport in optically thick arrays are addressed, QD-based photovoltaic technology can become a better candidate for practical application. In this article, the authors show how the possibilities of different deposition techniques can bring QD-based solar cells to the industrial level and discuss the challenges for perovskite QD solar cells in particular, to achieve largearea fabrication for further advancing technology to solve pivotal energy and environmental issues.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202107888.

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Perovskite Light‐Emitting Diodes: Perovskite Quantum Dots with Ultralow Trap Density by Acid Etching‐Driven Ligand Exchange for High Luminance and Stable Pure‐Blue Light‐Emitting Diodes (Adv. Mater. 15/2021)

Cited by 56 publications

References 0 publications

Surface Chemistry Engineering of Perovskite Quantum Dots: Strategies, Applications, and Perspectives

Surface Chemistry Engineering of Perovskite Quantum Dots: Strategies, Applications, and Perspectives

Highly Emissive Blue Quantum Dots with Superior Thermal Stability via In Situ Surface Reconstruction of Mixed CsPbBr₃–Cs₄PbBr₆ Nanocrystals

Colloidal Quantum Dot Solar Cells: Progressive Deposition Techniques and Future Prospects on Large‐Area Fabrication

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Perovskite Light‐Emitting Diodes: Perovskite Quantum Dots with Ultralow Trap Density by Acid Etching‐Driven Ligand Exchange for High Luminance and Stable Pure‐Blue Light‐Emitting Diodes (Adv. Mater. 15/2021)

Cited by 56 publications

References 0 publications

Surface Chemistry Engineering of Perovskite Quantum Dots: Strategies, Applications, and Perspectives

Surface Chemistry Engineering of Perovskite Quantum Dots: Strategies, Applications, and Perspectives

Highly Emissive Blue Quantum Dots with Superior Thermal Stability via In Situ Surface Reconstruction of Mixed CsPbBr3–Cs4PbBr6 Nanocrystals

Colloidal Quantum Dot Solar Cells: Progressive Deposition Techniques and Future Prospects on Large‐Area Fabrication

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Highly Emissive Blue Quantum Dots with Superior Thermal Stability via In Situ Surface Reconstruction of Mixed CsPbBr₃–Cs₄PbBr₆ Nanocrystals