Polarized Light‐Emitting Diodes Based on Patterned MoS<sub>2</sub> Nanosheet Hole Transport Layer

Choi, Gyu Jin; Le, Quyet Van; Choi, Kyoung Soon; Kwon, Ki Chang; Jang, Ho Won; Gwag, Jin Seog; Kim, Soo Young

doi:10.1002/adma.201702598

Cited by 71 publications

(32 citation statements)

References 26 publications

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“…We then demonstrate the electro-optical operations of an LC cell where the h-BN is employed as the planar-alignment agent. This investigation also falls in the current theme of research of the application of 2D materials in various optoelectronic devices [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional hexagonal boron nitride nanosheet as the planar-alignment agent in a liquid crystal-based electro-optic device

Basu¹,

Atwood²

2019

Opt. Express

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The planar-alignment agent in an electro-optic liquid crystal (LC) device plays an essential role for the LC's electro-optical characteristics. Rubbed polyimide (PI) layers are conventionally used as the planar-alignment agent in traditional liquid crystal displays (LCDs). Here we experimentally demonstrate that the 2D hexagonal boron nitride (h-BN) nanosheet can serve as the planar-alignment agent in an LC cell. This h-BN has higher chemical stability and more optical transparency than the PI layer. Two h-BN-covered indium tin oxide (ITO) glass slides (without any conventional PI layers) are placed together to fabricate an LC cell. A nematic LC inside this h-BN-based cell exhibits uniform planaralignment-which is probed by a crossed polarized optical microscope. This planaralignment at the molecular scale is achieved due to the coherent overlay of the benzene rings of the LC molecules on the hexagonal BN lattice. This h-BN-based LC cell shows the typical electro-optical effect when an electric field is applied via ITO electrodes. The dielectric measurement across this h-BN-based electro-optic cell shows a standard Fréedericksz transition of the LC, confirming that the 2D h-BN, as the planar-alignment agent, supplies adequate anchoring energy-which can be overcome by the Fréedericksz threshold voltage. Finally, we show that the h-BN-based LC cell exhibits more optical transparency than a regular PI alignment layer-based LC cell.

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Section: Introductionmentioning

confidence: 99%

Two-dimensional hexagonal boron nitride nanosheet as the planar-alignment agent in a liquid crystal-based electro-optic device

Basu¹,

Atwood²

2019

Opt. Express

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“…Molybdenum disulfide (MoS 2 ), a key member of the class of materials known as layered transition metal dichalcogenides (TMDCs), has attracted tremendous interest from the scientific community over the past few years because of its applications in various areas, including electronics, optoelectronics, and physicochemical and biomedical sensors [1][2][3][4][5][6][7] . In particular, large-scale monolayer MoS 2 synthesized via chemical vapor deposition (CVD) represents an ideal choice for fabricating active semiconducting channels for diodes, transistors, sensors, and other related systems [8][9][10][11] .…”

Section: Introductionmentioning

confidence: 99%

Degradation behaviors and mechanisms of MoS2 crystals relevant to bioabsorbable electronics

et al. 2018

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Monolayer molybdenum disulfide (MoS 2 ) exhibits unique semiconducting and bioresorption properties, giving this material enormous potential for electronic/biomedical applications, such as bioabsorbable electronics. In this regard, understanding the degradation performance of monolayer MoS 2 in biofluids allows modulation of the properties and lifetime of related bioabsorbable devices and systems. Herein, the degradation behaviors and mechanisms of monolayer MoS 2 crystals with different misorientation angles are explored. High-angle grain boundaries (HAGBs) biodegrade faster than low-angle grain boundaries (LAGBs), exhibiting degraded edges with wedge and zigzag shapes, respectively. Triangular pits that formed in the degraded grains have orientations opposite to those of the parent crystals, and these pits grow into larger pits laterally. These behaviors indicate that the degradation is induced and propagated based on intrinsic defects, such as grain boundaries and point defects, because of their high chemical reactivity due to lattice breakage and the formation of dangling bonds. High densities of dislocations and point defects lead to high chemical reactivity and faster degradation. The structural cause of MoS 2 degradation is studied, and a feasible approach to study changes in the properties and lifetime of MoS 2 by controlling the defect type and density is presented. The results can thus be used to promote the widespread use of two-dimensional materials in bioabsorption applications.

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“…Furthermore, the same research group fabricated few‐layer (≈2 nm) polycrystalline MoS 2 nanosheets from (NH 4 ) 2 MoS 4 by sequential rubbing and ion‐beam treatment, which could be used as not only a hole injection layer but also a template layer for inducing the molecular ordering of poly(9,9‐dioctylfluorene‐ alt ‐benzothiadiazole) and poly[(9,9‐di‐ n ‐octylfluorenyl‐2,7‐diyl)‐ alt ‐(benzo[2,1,3]thiadiazol‐4,8‐diyl)] (F8BT) (Figure d). The resulting devices showed improved efficiency and polarized light‐emitting behavior with a polarization ratio of 62.5:1 in the emission spectrum (Figure e) . This work opened up a new avenue for the development of OLEDs embedded with 2D materials …”

Section: Electronic and Optoelectronic Applicationsmentioning

confidence: 78%

“…The resulting devices showed improved efficiency and polarized light‐emitting behavior with a polarization ratio of 62.5:1 in the emission spectrum (Figure e) . This work opened up a new avenue for the development of OLEDs embedded with 2D materials …”

Section: Electronic and Optoelectronic Applicationsmentioning

confidence: 78%

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2D–Organic Hybrid Heterostructures for Optoelectronic Applications

Sun

Choi

et al. 2019

Advanced Materials

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The unique properties of hybrid heterostructures have motivated the integration of two or more different types of nanomaterials into a single optoelectronic device structure. Despite the promising features of organic semiconductors, such as their acceptable optoelectronic properties, availability of low-cost processes for their fabrication, and flexibility, further optimization of both material properties and device performances remains to be achieved. With the emergence of atomically thin 2D materials, they have been integrated with conventional organic semiconductors to form multidimensional heterostructures that overcome the present limitations and provide further opportunities in the field of optoelectronics. Herein, a comprehensive review of emerging 2D-organic heterostructures-from their synthesis and fabrication to their state-of-the-art optoelectronic applications-is presented. Future challenges and opportunities associated with these heterostructures are highlighted.solution-processed on any substrate inexpensively and at relatively low temperatures, which is highly advantageous for their scale-up from fundamental studies to industrial-level production. [6][7][8][9][10] Initial examples of developed organic semiconductors include field-effect transistors (FETs), [4,5,[11][12][13][14][15] photodetectors (PDs), [5,16,17] photovoltaics (PVs), [5,16,18,19] light-emitting diodes (LEDs), [5,16,20] and so on. In spite of the demonstration of promising prototypes of organic semiconductors, their development and optimization for highperformance device applications remain a challenge. In particular, it is becoming increasingly difficult to impart suitable properties to individual materials and realize appropriate physical dimensions in order to satisfy increasing demands of multifunctionality for fundamental studies, device designs, and performance optimization. [21,22] Consequently, such challenges and opportunities can be addressed by performing multidimensional integration or hybridization of organic semiconductors with various types of materials having potentially novel functionalities and unique properties.2D van der Waals (vdW) materials are the most obvious candidate for such hybridization with organic semiconductors. [22,23] Since the discovery of graphene, which opened up new avenues ranging from fundamental studies to real-world applications, [24][25][26][27] several other groups of 2D vdW materials have also been discovered, such as hexagonal boron nitride (h-BN), [28,29] transition metal dichalcogenides (TMDCs), [23,[30][31][32][33][34] black phosphorus (BP), [35][36][37][38][39][40] borophene, [41][42][43] silicene, [43] and germanene. [43] The 2D structure has been demonstrated to possess several exceptional electrical, optical, mechanical, and thermal properties vis-à-vis its corresponding bulk counterpart. [22,25,27] Most importantly, from the viewpoint of hybridization with organic semiconductors, the atomically flat and dangling-bond-free surface of 2D vdW materials not only provides an ideal int...

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Polarized Light‐Emitting Diodes Based on Patterned MoS₂ Nanosheet Hole Transport Layer

Cited by 71 publications

References 26 publications

Two-dimensional hexagonal boron nitride nanosheet as the planar-alignment agent in a liquid crystal-based electro-optic device

Two-dimensional hexagonal boron nitride nanosheet as the planar-alignment agent in a liquid crystal-based electro-optic device

Degradation behaviors and mechanisms of MoS2 crystals relevant to bioabsorbable electronics

2D–Organic Hybrid Heterostructures for Optoelectronic Applications

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Polarized Light‐Emitting Diodes Based on Patterned MoS2 Nanosheet Hole Transport Layer

Cited by 71 publications

References 26 publications

Two-dimensional hexagonal boron nitride nanosheet as the planar-alignment agent in a liquid crystal-based electro-optic device

Two-dimensional hexagonal boron nitride nanosheet as the planar-alignment agent in a liquid crystal-based electro-optic device

Degradation behaviors and mechanisms of MoS2 crystals relevant to bioabsorbable electronics

2D–Organic Hybrid Heterostructures for Optoelectronic Applications

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Product

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Polarized Light‐Emitting Diodes Based on Patterned MoS₂ Nanosheet Hole Transport Layer