Phosphor-free white light-emitting diodes

Guo, Xia; Liu, Qiao-Li; Li, Chong; Liu, Bai; Dong, Jian; Guang-di, Shen

doi:10.1088/1674-1056/24/6/068505

Cited by 10 publications

(5 citation statements)

References 74 publications

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“…Yang et al [15] found that switching the ferroelectric state of the BFO layer did not change the photovoltaic response. Guo et al [16] suggested that the sign of photocurrent could be independent of the direction of polarization when the modulation of the energy band induced by oxygen vacancies is large enough to offset that induced by polarization, whereas the oxygen vacancies act as shunts and trapping center due to their positively charged and higher mobility. Therefore, clearly more detailed studies are necessary to elaborate on the role of ferroelectricity and oxygen vacancies in enabling the photovoltaic effect and the switchable phenomenon.…”

mentioning

confidence: 99%

Switchable photovoltaic effect in Au/Bi0.9La0.1FeO3/La0.7Sr0.3MnO3 heterostructures

Gao

Cai

et al. 2016

Materials Chemistry and Physics

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mentioning

confidence: 99%

Switchable photovoltaic effect in Au/Bi0.9La0.1FeO3/La0.7Sr0.3MnO3 heterostructures

Gao

Cai

et al. 2016

Materials Chemistry and Physics

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“…Nowadays, InGaN/GaN multiple-quantum-well (MQW)based light-emitting diodes (LEDs) are widely used in general lighting, displays, backlighting, and communications [1][2][3] due to the tenability of the emitted light from near-ultraviolet to visible and up to near-infrared spectral range by tuning the In composition in the InGaN well layers (WLs). [4] However, there remain many difficulties in achieving high-performance LEDs, which need to be overcome.…”

Section: Introductionmentioning

confidence: 99%

Efficiency droop in InGaN/GaN-based LEDs with a gradually varying In composition in each InGaN well layer

Qu¹,

Xu²,

Wang³

et al. 2022

Chinese Phys. B

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Temperature-dependent and driving current-dependent electroluminescence spectra of two different InGaN/GaN multiple quantum well structures SA and SB are investigated, with the In composition in each well layer (WL) along the growth direction progressively increasing for SA and progressively decreasing for SB. The results show that SB exhibits an improved efficiency droop compared with SA. This phenomenon can be explained as follows: owing to the difference in growth pattern of the WL between these two samples, the terminal region of the WL in SB contains fewer In atoms than in SA, and therefore the former undergoes less In volatilization than the latter during the waiting period required for warming-up due to the difference in the growth temperature between well and barrier layers. This results in SB having a deeper triangular-shaped potential well in its WL than SA, which strongly confines the carriers to the initial region of the WL to prevent them from leaking to the p-GaN side, thus improving the efficiency droop. Moreover, the improvement in the efficiency droop for SB is also partly attributed to its stronger Coulomb screening effect and carrier localization effect.

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“…Much attention has been paid to white light-emitting diodes (WLEDs) for solid-state lighting applications due to their excellent brightness, low power consumption, long lifetime, and environmental friendliness. [1][2][3] Generally, white light emission results from the use of phosphor to transform part of emissions of blue LEDs to the yellow-green spectral range. The transformation is related to an energy loss termed Stokes' loss, which is on the order of 25% and thus restricts the highest attainable phosphor-converted WLED efficiency to much less than 100%; [4,5] however, in principle, one can avoid the loss through the use of phosphor-free monolithic WLEDs, which are integrated by blue, green, and even red long-wavelength InGaN-based LEDs, since the nitride system can cover the entire spectral region of the emitted light from near-ultraviolet to near-infrared by adjusting the composition of InGaN alloy.…”

Section: Introductionmentioning

confidence: 99%

Combined effects of carrier scattering and Coulomb screening on photoluminescence in InGaN/GaN quantum well structure with high In content*

Li¹,

Xu²,

Wang³

et al. 2021

Chinese Phys. B

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Photoluminescence (PL) spectra of two different green InGaN/GaN multiple quantum well (MQW) samples S1 and S2, respectively with a higher growth temperature and a lower growth temperature of InGaN well layers are analyzed over a wide temperature range of 6 K–330 K and an excitation power range of 0.001 mW–75 mW. The excitation power-dependent PL peak energy and linewidth at 6 K show that in an initial excitation power range, the emission process of the MQW is dominated simultaneously by the combined effects of the carrier scattering and Coulomb screening for both the samples, and both the carrier scattering effect and the Coulomb screening effect are stronger for S2 than those for S1; in the highest excitation power range, the emission process of the MQWs is dominated by the filling effect of the high-energy localized states for S1, and by the Coulomb screening effect for S2. The behaviors can be attributed to the fact that sample S2 should have a higher amount of In content in the InGaN well layers than S1 because of the lower growth temperature, and this results in a stronger component fluctuation-induced potential fluctuation and a stronger well/barrier lattice mismatch-induced quantum-confined Stark effect. This explanation is also supported by other relevant measurements of the samples, such as temperature-dependent peak energy and excitation-power-dependent internal quantum efficiency.

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Phosphor-free white light-emitting diodes

Cited by 10 publications

References 74 publications

Switchable photovoltaic effect in Au/Bi0.9La0.1FeO3/La0.7Sr0.3MnO3 heterostructures

Switchable photovoltaic effect in Au/Bi0.9La0.1FeO3/La0.7Sr0.3MnO3 heterostructures

Efficiency droop in InGaN/GaN-based LEDs with a gradually varying In composition in each InGaN well layer

Combined effects of carrier scattering and Coulomb screening on photoluminescence in InGaN/GaN quantum well structure with high In content*

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