Impact of the Bending on the Electroluminescence of Flexible InGaN/GaN Light-Emitting Diodes

Tabares, G.; Mhedhbi, S.; Lesecq, Marie; Damilano, B.; Brault, J.; Chenot, Sébastien; Ebongue, A.; Altuntas, P.; Defrance, N.; Hoel, Virginie; Cordier, Y.

doi:10.1109/lpt.2016.2563258

Cited by 8 publications

(6 citation statements)

References 20 publications

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“…As the injected current rises to 1.6 mA, the peak shifts to shorter wavelengths and broadens simultaneously, which is dominated by the band-filling effect. Ultimately, at a higher injected current, the peak shows a redshift due to the self-heating effect, which shrinks the bandgap energy. , The variation tendency of the peak position and fwhm with the injection current is similar at all bending conditions.…”

Section: Resultsmentioning

confidence: 99%

Fabrication of GaN-Based Flexible VLEDs with Double-Side Light Emitting

Yang,

Gu,

Yang

et al. 2024

ACS Photonics

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Flexible optoelectronic devices are promising in a broad range of applications, such as virtual reality (VR), deformable displays, wearable optoelectronic devices, and consumer electronics, due to their excellent mechanical flexibility. Inorganic gallium nitride-based (GaN) semiconductor lightemitting devices with higher stability, superior color rendition, and longer lifespan have great potential for further advancing the development of flexible optoelectronic devices. In this study, we present a novel method for fabricating flexible GaN-based vertical LEDs (VLEDs). Based on the soft transparent substrate prepared by cured photosensitive resin and the single-substrate transfer technique, double-sided light output and flexible GaN-based blue VLEDs were successfully fabricated. The S-shaped electrodes in the device channel can enhance the electrode flexibility. When subjected to downward bending, the electroluminescence (EL) peak of flexible VLED shifted from 458.3 to 458.5 nm, accompanied by a decrease in EL intensity by approximately 52%. Under upward bending, the EL peak position initially exhibited a blue shift to 458.1 nm, and the luminous intensity increased by about 13% compared with the flatness state. However, the EL peak shows a red shift to 459.1 nm and a decrease of luminous intensity with further increasing the upward bending degree. These observations can be attributed to the piezo-phototronic effect. The applied external stresses can induce polarization charges at the interface of InGaN/GaN multiple quantum wells (MQWs), which alter the energy band structure of InGaN/GaN MQWs and modulate the optoelectronic properties of the device. The flexible GaN-based blue VLED with double-sided light output can provide new strategies for the development of dual-sided flexible displays and wearable human−machine interaction.

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Section: Resultsmentioning

confidence: 99%

Fabrication of GaN-Based Flexible VLEDs with Double-Side Light Emitting

Yang,

Gu,

Yang

et al. 2024

ACS Photonics

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“…Finally, the photoresist deposited on the front side was removed by immersion in acetone leading to the release of the LEDs from the carrier substrate. A similar process was previously used for the transfer of transistors based on (Al,Ga)N/GaN heterostructures or (Ga,In)N/GaN LEDs [10], [11], and [24].…”

Section: Methodsmentioning

confidence: 99%

“…LEDs can be grown on sapphire substrate and detached using a laser lift-off technique [13]- [20] or can be grown on an h-BN release layer [21]. Alternatively, structures grown on silicon can be transferred after the full etching of the silicon substrate [22]- [24]. More advanced realizations such as the transfer of arrays of µLEDs on flexible substrates have also been demonstrated [22], [25].…”

Section: Introductionmentioning

confidence: 99%

Optical and Thermal Performances of (Ga,In)N/GaN Light Emitting Diodes Transferred on a Flexible Tape

Damilano

Lesecq

Zhou

et al. 2018

IEEE Photon. Technol. Lett.

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Blue (Ga,In)N-based light-emitting diodes (LEDs) grown on a Si(111) substrate by metal-organic vapor phase epitaxy are transferred on a flexible tape after the Si substrate removal. Their optical and thermal behaviors are measured and compared to those of regular LEDs on Si. The light output power of the flexible LEDs is increased due to a higher light extraction efficiency related to the removal of the absorbing Si substrate. However, the maximum output power is limited by thermal effects due to the lower thermal conductivity of the flexible tape. Monitoring the electroluminescence wavelength of the flexible LEDs allows determining their acceptable operating range. The maximum flexible LED luminance is 5 × 10 5 cd/m 2 .

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“…This novel orientation avoids common problems observed in flexible LEDs, such as peak emission wavelength shifts and decreased light output during applied mechanical stress. [8][9][10][11] This degradation is mainly due to a strain-induced piezoelectric response affecting the active region of the LED. As bending increases, piezoelectric fields produced in the quantum wells create a measureable peak shift in the electroluminescence (EL) characteristics that affects spectral uniformity of the LEDs and degrades the performance of the light emitters for applications, such as solid-state lighting and next-generation displays.…”

Section: Introductionmentioning

confidence: 99%

Optically invariant InGaN nanowire light-emitting diodes on flexible substrates under mechanical manipulation

Asad

Wang

et al. 2019

npj Flex Electron

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The integration of GaN-based light-emitting diodes (LEDs) onto flexible platforms provides opportunities for conformal lighting, wearable electronics, and bendable displays. While this technology may enhance the functionality of the light source, the development of flexible GaN LEDs suffers from performance degradation, when mechanical bending is applied during operation. A unique approach to eliminate the degradation employs dot-in-wire structures, using cylindrical light-emitting heterostructures that protrude above the flexible platform, separating the active light-emitting region from the bending substrate. Here, we demonstrate the optical enhancement of nanowire light emitters by changing the geometric orientation within a 1 × 1 mm 2 array of nanowires on a flexible platform through bending of the substrate platform. The flexible structures were achieved by transferring GaN nanowire LEDs from sapphire substrates onto flexible polyethylene terephthalate (PET) using a "paste-and-cut" integration process. The I-V characteristics of the nanowire LEDs showed negligible change after integration onto the PET, with a turn-on voltage of 2.5 V and a forward current of 400 μA at 4 V. A significant advantage for the nanowire devices on PET was demonstrated by tilting the LEDs through substrate bending that increased the electroluminescence (EL) intensity, while the I-V characteristics and the EL peak position remained constant. Through finite-element analysis and three-dimensional finite-difference time-domain modeling, it was determined that tilting the protruding devices changed the effective distance between the structures, enhancing their electromagnetic coupling to increase light output without affecting the electrical properties or peak emission wavelength of the LEDs.

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Impact of the Bending on the Electroluminescence of Flexible InGaN/GaN Light-Emitting Diodes

Cited by 8 publications

References 20 publications

Fabrication of GaN-Based Flexible VLEDs with Double-Side Light Emitting

Fabrication of GaN-Based Flexible VLEDs with Double-Side Light Emitting

Optical and Thermal Performances of (Ga,In)N/GaN Light Emitting Diodes Transferred on a Flexible Tape

Optically invariant InGaN nanowire light-emitting diodes on flexible substrates under mechanical manipulation

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