carrier lifetime
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2022 ◽  
Author(s):  
Bo-Han Li ◽  
Huang Li ◽  
Zhipeng Xuan ◽  
Wen Zeng ◽  
Jia-Cheng Wang ◽  
...  

Abstract Understanding the nature of photogenerated carriers and their subsequent dynamics in perovskites is important for the development of related materials and devices. Most ultrafast dynamic measurements on the perovskite materials were conducted under high carrier densities, which likely obscures the genuine dynamics at low carrier densities under solar illumination conditions. In this study, we presented a detailed experimental study of the carrier density-dependent dynamics in hybrid lead iodide perovskites using a highly sensitive transient absorption spectrometer. We found that the carrier lifetime was about a hundred nanosecond in the linear response range, representing sunlight excitation, which was much longer than under high carrier densities. We also elucidated that the fast carrier decay (<1 ps) and the medium decay processes (tens of ps) occurred via the defect state trapping, and we determined its effects on the utilization percentage of photogenerated carriers through quantitative analysis. Furthermore, we obtained the Shockley-Queisser limit that took into account the carrier trapping effect, which directly reflected the material performance.


Doklady BGUIR ◽  
2022 ◽  
Vol 19 (8) ◽  
pp. 50-57
Author(s):  
N. N. Vorsin ◽  
A. A. Gladyshchu ◽  
T. L. Kushner ◽  
N. P. Tarasiuk ◽  
S. V. Chugunov ◽  
...  

Ternary AlGaN alloys with a band gap of 3.4 to 6.2 eV are very promising for photodetectors in the UV wavelength range. Using the COMSOL MULTIPHYSICS software based on AlGaN, a p-i-n photodiode model was developed, including its I–V characteristic, spectral sensitivity of the received radiation, absorption coefficient as a function of the aluminum fraction and the depletion layer thickness. To calculate the process of interaction of a semiconductor with EM radiation, we used a model based on the use of an element of the transition matrix through the carrier lifetime during spontaneous recombination. In this case, the peak sensitivity of the photodiode is from 0.08 to 0.18 A/W at wavelengths of 0.2–0.33 µm. This is in line with experimental results taken from the relevant literature.


2022 ◽  
Author(s):  
Ziwei Zheng ◽  
Shiyu Wang ◽  
Yue Hu ◽  
Yaoguang Rong ◽  
Anyi Mei ◽  
...  

Perovskite materials have been particularly eye-catching by virtue of its excellent properties, such as high light absorption coefficient, long carrier lifetime, low exciton binding energy and bipolarity transmission, etc. Limited...


Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1564
Author(s):  
Xuan-Viet Pham ◽  
Ba-Duc Tran ◽  
Duy-Cuong Nguyen ◽  
Tu Nguyen ◽  
Minh-Vuong Nguyen ◽  
...  

In this study, low-dimensional CsPbBr3@CoBr2 super-nanowire (SNW) structures were synthesized via a one-pot heating strategy for highly blue emissions. By introducing CoBr2 to CsPbBr3 precursors, the shape of perovskite nanocrystals was changed from cuboids to a super-nanowire structure, as revealed through a transmission electron microscope. SNWs were formed from stacked segments of nano-plates (lateral dimension of 10–12 nm and thickness of ~2.5 nm) with lengths of several microns. The fabricated sample absorbs light at a wavelength of <450 nm, and it is emitted at a wavelength of 475 nm. It also has a radiant flux conversion efficiency of up to 85% when stimulated by a 430 nm LED light source. The average decay time of up to 80 µs indicates that they effectively prevent the recombination of electron–hole pair. The optical performance still remains over 65% when the ambient temperature is up to 120 °C compared with that under room temperature. The excellent color purity, optical quantum efficiency, long carrier lifetime, and thermal stability make CsPbBr3@CoBr2 SNWs highly promising for a range of photolumicescence applications, such as a high color rendering index lighting and transparent blue emissive screen.


2021 ◽  
Author(s):  
Yuanchao Huang ◽  
Rong Wang ◽  
Yiqiang Zhang ◽  
Deren Yang ◽  
Xiaodong Pi

Abstract As a common impurity in 4H-silicon carbide (4H-SiC), hydrogen (H) may play a role in the tuning of the electronic properties of 4H-SiC. In this work, we systemically explore the effect of H on the electronic properties of both n-type and p-type 4H-SiC. The passivation of H for intrinsic defects such as carbon vacancies (VC) and silicon vacancies (VSi) in 4H-SiC is also evaluated. We find that interstitial H at the bonding center of the Si-C bond (Hi bc) and interstitial H at the tetrahedral center of Si (Hi Si-te) dominate the defect configurations of H in p-type and n-type 4H-SiC, respectively. For n-type 4H-SiC, the compensation of Hi Si-te is found to pin the Fermi energy and hinder the increase of electron concentration for highly N-doped 4H-SiC. The compensation of Hi bc is negligible compared to that of VC on the p-type doping of Al-doped 4H-SiC. We have further examined whether H can passivate VC and improve carrier lifetime in 4H-SiC. It turns out that nonequilibrium passivation of VC by H is effective to eliminate the defect states of VC, which enhances the carrier lifetime of moderately doped 4H-SiC. Regarding the quantum-qubit applications of 4H-SiC, we find that H can readily passivate VSi during the creation of VSi centers. Thermal annealing is needed to decompose the resulting VSi-nH (n=1~4) complexes and promote the uniformity of the photoluminescence of VSi arrays in 4H-SiC. The current work may inspire the further development of the impurity engineering of H in 4H-SiC.


2021 ◽  
Vol 119 (23) ◽  
pp. 232101
Author(s):  
Shiqiang Fu ◽  
Jiahao Wang ◽  
Like Huang ◽  
Xiaohui Liu ◽  
Jing Zhang ◽  
...  

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3221
Author(s):  
Yan Xing ◽  
Jing Cheng ◽  
Heping Li ◽  
Dandan Lin ◽  
Yuting Wang ◽  
...  

Ceramic fiber photocatalysts fabricated by electrospinning hold great potential in alleviating global environmental and energy issues. However, many challenges remain in improving their photocatalytic efficiencies, such as the limited carrier lifetime and solar energy utilization. To overcome these predicaments, various smart strategies have been invented and realized in ceramic fiber photocatalysts. This review firstly attempts to summarize the fundamental principles and bottlenecks of photocatalytic processes. Subsequently, the approaches of doping, surface plasmon resonance, and up-conversion fluorescent to enlarge the light absorption range realized by precursor composition design, electrospinning parameter control, and proper post heat-treatment process are systematically introduced. Furthermore, methods and achievements of prolonging the lifetime of photogenerated carriers in electrospun ceramic fiber photocatalysts by means of introducing heterostructure and defective composition are reviewed in this article. This review ends with a summary and some perspectives on the future directions of ceramic fiber photocatalysts.


2021 ◽  
Vol 11 (22) ◽  
pp. 10937
Author(s):  
Mahmoud Abdelhamid ◽  
Dorota Korte ◽  
Humberto Cabrera ◽  
Olena Pliekhova ◽  
Zeinab Ebrahimpour ◽  
...  

Cu/Zr-modified TiO2 photocatalysts were prepared in the form of nanopowders and characterized by photothermal spectrometry, UV–Vis spectrophotometry and x-ray diffraction (XRD) to investigate the effect of Cu/Zr content on their thermo-optical and transport properties. Adding Cu (0.05%) caused a change in the light absorption range limit, which reduced from 3.25 eV for pure TiO2 to 2.85 eV for Cu-modified TiO2. The decrease in energy band gap was accompanied by a 19.5% decrease in the charge carrier lifetime, which is not favorable for photocatalysis. The decrease in charge carrier lifetime can be minimized by additional modification of TiO2 with Zr (1%), which showed insignificant effects on the energy band gap of the investigated materials. Furthermore, modification of TiO2 with Zr affected the material’s structure and increased its specific surface area, which improved the adsorption of degraded compounds as well as the absorption of light. Altogether, these effects resulted in higher photocatalytic degradation rate constants of the investigated TiO2-based photocatalyst. It was also found that modification of TiO2 with Cu and/or Zr increases both the material’s thermal diffusivity and conductivity due to changes in the band gap and structure of material. Beam deflection spectrometry (BDS) has demonstrated high potential in materials’ characterization which stems from its high sensitivity and precision.


2021 ◽  
Vol 119 (18) ◽  
pp. 182106
Author(s):  
K. Shima ◽  
R. Tanaka ◽  
S. Takashima ◽  
K. Ueno ◽  
M. Edo ◽  
...  

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