Current crowding impact at spatially and temporarily resolved thermal characters of large-area AlGaInP light emitting diodes operating in dimming/flashing modes

AbstractWith rapid advances of perovskite light-emitting diodes (PeLEDs), the large-scale fabrication of patterned PeLEDs towards display panels is of increasing importance. However, most state-of-the-art PeLEDs are fabricated by solution-processed techniques, which are difficult to simultaneously achieve high-resolution pixels and large-scale production. To this end, we construct efficient CsPbBr3 PeLEDs employing a vacuum deposition technique, which has been demonstrated as the most successful route for commercial organic LED displays. By carefully controlling the strength of the spatial confinement in CsPbBr3 film, its radiative recombination is greatly enhanced while the nonradiative recombination is suppressed. As a result, the external quantum efficiency (EQE) of thermally evaporated PeLED reaches 8.0%, a record for vacuum processed PeLEDs. Benefitting from the excellent uniformity and scalability of the thermal evaporation, we demonstrate PeLED with a functional area up to 40.2 cm2 and a peak EQE of 7.1%, representing one of the most efficient large-area PeLEDs. We further achieve high-resolution patterned perovskite film with 100 μm pixels using fine metal masks, laying the foundation for potential display applications. We believe the strategy of confinement strength regulation in thermally evaporated perovskites provides an effective way to process high-efficiency and large-area PeLEDs towards commercial display panels.

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Numerical Simulation on Electrical-Thermal Properties of Gallium-Nitride-Based Light-Emitting Diodes Embedded in Board

Advances in OptoElectronics ◽

10.1155/2012/495981 ◽

2012 ◽

Vol 2012 ◽

pp. 1-6 ◽

Cited By ~ 4

Author(s):

Xing-ming Long ◽

Rui-jin Liao ◽

Jing Zhou

Keyword(s):

Finite Element ◽

Gallium Nitride ◽

Indium Tin Oxide ◽

Light Emitting Diodes ◽

Thermal Characteristics ◽

Junction Temperature ◽

Current Crowding ◽

Total Thermal Resistance ◽

Light Emitting ◽

Packaging Structure

The electrical-thermal characteristics of gallium-nitride- (GaN-) based light-emitting diodes (LED), packaged by chips embedded in board (EIB) technology, were investigated using a multiphysics and multiscale finite element code, COMSOL. Three-dimensional (3D) finite element model for packaging structure has been developed and optimized with forward-voltage-based junction temperatures of a 9-chip EIB sample. The sensitivity analysis of the simulation model has been conducted to estimate the current and temperature distribution changes in EIB LED as the blue LED chip (substrate, indium tin oxide (ITO)), packaging structure (bonding wire and chip numbers), and system condition (injection current) changed. This method proved the reliability of simulated results in advance and useful material parameters. Furthermore, the method suggests that the parameter match on Shockley's equation parameters, Rs, nideal, and Is, is a potential method to reduce the current crowding effect for the EIB LED. Junction temperature decreases by approximately 3 K to 10 K can be achieved by substrate thinning, ITO, and wire bonding. The nonlinear-decreasing characteristics of total thermal resistance that decrease with an increase in chip numbers are likely to improve the thermal performance of EIB LED modules.

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Passive cooling of large-area organic light-emitting diodes

Organic Electronics ◽

10.1016/j.orgel.2013.04.023 ◽

2013 ◽

Vol 14 (8) ◽

pp. 1939-1945 ◽

Cited By ~ 14

Author(s):

Philipp Schwamb ◽

Thilo C.G. Reusch ◽

Christoph J. Brabec

Keyword(s):

Light Emitting Diodes ◽

Organic Light Emitting Diodes ◽

Passive Cooling ◽

Large Area ◽

Light Emitting ◽

Organic Light

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GaN-Based Light-Emitting Diodes with Graphene Buffers for Their Application to Large-Area Flexible Devices

IEICE Transactions on Electronics ◽

10.1587/transele.e100.c.161 ◽

2017 ◽

Vol E100.C (2) ◽

pp. 161-165 ◽

Cited By ~ 3

Author(s):

Jitsuo OHTA ◽

Jeong Woo SHON ◽

Kohei UENO ◽

Atsushi KOBAYASHI ◽

Hiroshi FUJIOKA

Keyword(s):

Light Emitting Diodes ◽

Large Area ◽

Light Emitting ◽

Flexible Devices

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High-performance large-area quasi-2D perovskite light-emitting diodes

Nature Communications ◽

10.1038/s41467-021-22529-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Changjiu Sun ◽

Yuanzhi Jiang ◽

Minghuan Cui ◽

Lu Qiao ◽

Junli Wei ◽

...

Keyword(s):

High Performance ◽

Light Emitting Diodes ◽

Intermediate Phase ◽

Formation Enthalpy ◽

Phase Segregation ◽

Phase Changes ◽

Large Area ◽

High Brightness ◽

Light Emitting ◽

Performance Decline

AbstractSerious performance decline arose for perovskite light-emitting diodes (PeLEDs) once the active area was enlarged. Here we investigate the failure mechanism of the widespread active film fabrication method; and ascribe severe phase-segregation to be the reason. We thereby introduce L-Norvaline to construct a COO−-coordinated intermediate phase with low formation enthalpy. The new intermediate phase changes the crystallization pathway, thereby suppressing the phase-segregation. Accordingly, high-quality large-area quasi-2D films with desirable properties are obtained. Based on this, we further rationally adjusted films’ recombination kinetics. We reported a series of highly-efficient green quasi-2D PeLEDs with active areas of 9.0 cm2. The peak EQE of 16.4% is achieved in <n > = 3, represent the most efficient large-area PeLEDs yet. Meanwhile, high brightness device with luminance up to 9.1 × 104 cd m−2 has achieved in <n> = 10 film.

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Surface Cleaning Challenges for Organic Light Emitting Diodes

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.314.3 ◽

2021 ◽

Vol 314 ◽

pp. 3-8

Author(s):

Noel Giebink

Keyword(s):

Light Emitting Diodes ◽

Surface Cleaning ◽

Organic Light Emitting Diodes ◽

Large Area ◽

Light Emitting ◽

Organic Light ◽

Organic Optoelectronic Devices ◽

Soft Thin Film ◽

Organic Optoelectronic

Organic optoelectronic devices such as light-emitting diodes and solar cells present unique challenges for surface cleaning and preparation because of their large area and the ‘soft’, thin film nature of the materials involved. This paper gives an introduction to this class of semiconductor devices and covers a recent example of how surface cleaning impacts the long-term reliability of organic light-emitting diodes being commercialized for solid-state lighting.

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A 3 W High-Voltage Single-Chip Green Light-Emitting Diode with Multiple-Cells Network

Journal of Nanomaterials ◽

10.1155/2015/248191 ◽

2015 ◽

Vol 2015 ◽

pp. 1-4 ◽

Cited By ~ 1

Author(s):

W. Wang ◽

Y. Cai ◽

Y. B. Zhang ◽

H. J. Huang ◽

W. Huang ◽

...

Keyword(s):

High Voltage ◽

Light Emitting Diode ◽

Light Output ◽

Green Light ◽

Current Crowding ◽

Single Chip ◽

Light Output Power ◽

Large Area ◽

Light Emitting ◽

Multiple Cells

A parallel and series network structure was introduced into the design of the high-voltage single-chip (HV-SC) light-emitting diode to inhibit the effect of current crowding and to improve the yield. Using such a design, a6.6×5 mm2large area LED chip of 24 parallel stages was demonstrated with 3 W light output power (LOP) at the current of 500 mA. The forward voltage was measured to be 83 V with the same current injection, corresponding to 3.5 V for a single stage. The LED chip’s average thermal resistance was identified to be 0.28 K/W by using infrared thermography analysis.

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