Generated Carrier Dynamics in V-Pit-Enhanced InGaN/GaN Light-Emitting Diode

Ajia, Idris A.; Edwards, P. R.; Pak, Yusin; Belekov, Ermek; Roldán, Manuel A.; Wei, Nini; Liu, Zhiqiang; Martin, Robert; Roqan, Iman S.

doi:10.1021/acsphotonics.7b00944

Cited by 72 publications

(50 citation statements)

References 46 publications

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“…As can be seen from the TRPL measurements, in the longer wavelength (500−510 nm) range (related peak with a dominant intensity is centered at 506 nm), the carrier PL lifetimes exhibit a slow mono-exponential decay. Based on the rate equation, this slower single exponential suggests high radiative recombination rate, which concurs with the high PL intensity and is in line with the results obtained in previous studies [29][30][31][32] . On the other hand, in the shorter wavelength (450−490 nm) range, the carrier lifetimes exhibit faster bi-exponential decay, due to the presence of multiple centers resulting from different states.…”

Section: Resultssupporting

confidence: 91%

Self-Patterned CsPbBr₃ Nanocrystals for High-Performance Optoelectronics

Xin

Pak

Mitra

et al. 2019

ACS Appl. Mater. Interfaces

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All-inorganic lead halide perovskites are promising materials for many optoelectronic applications. However, two issues that arise during device fabrication hinder their practical use, namely inadequate continuity of coated inorganic perovskite films across large areas and inability to integrate these films with traditional photolithography due to poor adhesion to wafers. Herein, for the first time, to address these issues, we show a room-temperature synthesis process employed to produce of CsPbBr 3 perovskite nanocrystals with twodimensional (2D) nanosheet features. Due to the unique properties of these 2D nanocrystals, including the "self-assembly" characteristic, and "double solvent evaporation inducing selfpatterning" strategy are used to generate high-quality patterned thin films in selected areas automatically after-drop-casting, enabling fabrication of high-performance devices without using complex and expensive fabrication processing techniques. The films are free from

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Section: Resultssupporting

confidence: 91%

Self-Patterned CsPbBr₃ Nanocrystals for High-Performance Optoelectronics

Xin

Pak

Mitra

et al. 2019

ACS Appl. Mater. Interfaces

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“…The carrier dynamics of CsPbI 3 and CsPbBr 3 samples were investigated using time-resolved photoluminescence (TRPL) measurements to further confirm our findings and better understand the optical phenomena observed in Figure 3c,d (Table S1 in the Supporting Information shows the RT TRPL parameters). The total decay lifetime was fitted with bi-exponential decay functions (comprising both fast and slow decay components) due to the presence of multiple recombination centers, [51,52] as shown in Table S1. TRPL results indicated that the total lifetime was dominated by the slow decay component, which is indicative of highquality materials.…”

Section: Advanced Optical Analysis and The Band Structurementioning

confidence: 99%

“…To understand such carrier lifetime behavior in both materials, radiative and non-radiative components were analyzed, [51,54,55] and the results are reported in Figure 3e,f. As shown in Figure 3d, the lifetime of CsPbBr 3 at RT was dominated by radiative recombination (as it is in the same ns range of the total lifetime).…”

Section: Advanced Optical Analysis and The Band Structurementioning

confidence: 99%

Identifying Carrier Behavior in Ultrathin Indirect‐Bandgap CsPbX₃ Nanocrystal Films for Use in UV/Visible‐Blind High‐Energy Detectors

Xin

Alaal

Mitra

et al. 2020

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and military devices. Among these applications, medical diagnostics is particularly significant, but it presently requires direct exposure to high doses of radiation, which is harmful to human health, increasing cancer risk, especially in children. [1,2] Hence, X-ray detectors possessing both high sensitivity and high resolution with a low light interface noise [3,4] are required to minimize the radiation exposure during routine medical diagnostics. In the pertinent literature, use of conventional semiconductors for direct X-ray detection has been reported by several groups, including amorphous Se, [5] crystalline Si, [6] Ge, [7] HgI 2 , [8] CdTe, [9,10] and CdZnTe, [9,10] indicating that the most effective materials are indirect bandgap semiconductors [5-10] that exhibit low light interference noise. However, as such devices possess low sensitivity due to the low atomic number values of their materials, [7] as well as they still require expensive fabrication and complex processing methods, there is a high industrial demand for cost-effective highly sensitive X-ray detectors that are more suited for mass production. Ionic perovskite crystals can be processed from solution at low temperatures, in contrast to covalent bond semiconductors, which require a high-temperature crystallization process. Consequently, lead halogen perovskite has emerged as a promising candidate due to its cost-effectiveness, high crystal quality, high absorption cross-section, high illumination, and ability to form High-energy radiation detectors such as X-ray detectors with low light photoresponse characteristics are used for several applications including, space, medical, and military devices. Here, an indirect bandgap inorganic perovskite-based X-ray detector is reported. The indirect bandgap nature of perovskite materials is revealed through optical characterizations, time-resolved photoluminescence (TRPL), and theoretical simulations, demonstrating that the differences in temperature-dependent carrier lifetime related to CsPbX 3 (X = Br, I) perovskite composition are due to the changes in the bandgap structure. TRPL, theoretical analyses, and X-ray radiation measurements reveal that the high response of the UV/visible-blind yellow-phase CsPbI 3 under high-energy X-ray exposure is attributed to the nature of the indirect bandgap structure of CsPbX 3. The yellowphase CsPbI 3-based X-ray detector achieves a relatively high sensitivity of 83.6 μCGy air −1 cm −2 (under 1.7 mGy air s −1 at an electron field of 0.17 V μm −1 used for medical diagnostics) although the active layer is based solely on an ultrathin (≈6.6 μm) CsPbI 3 nanocrystal film, exceeding the values obtained for commercial X-ray detectors, and further confirming good material quality. This CsPbX 3 X-ray detector is sufficient for cost-effective device miniaturization based on a simple design.

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“…No defect yellow luminescence (YL) band is observed, indicating superior crystal quality. 23,26 The RT PL emission spectrum of MAPI lm is shown in Fig. 1d.…”

Section: Resultsmentioning

confidence: 99%