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Article

Ultrafast Coherent Hole Injection at the Interface between CuSCN and Polymer PM6 Using Femtosecond Mid-Infrared Spectroscopy

(American Chemical Society (ACS), 2024-04-04) Healing, George; Nadinov, Issatay; Hadmojo, Wisnu Tantyo; Yin, Jun; Thomas, Simil; Bakr, Osman M.; Alshareef, Husam N.; Anthopoulos, Thomas D.; Mohammed, Omar F.; Chemistry; Chemical Science Program; Physical Sciences and Engineering; Physical Science and Engineering (PSE) Division; KAUST Solar Center; KAUST Solar Center (KSC); Catalysis Research Center; KAUST Catalysis Center (KCC); Material Science and Engineering; Material Science and Engineering Program; Advanced Membranes and Porous Materials Center; Advanced Membranes and Porous Materials Research Center; Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong

Tracking the dynamics of ultrafast hole injection into copper thiocyanate (CuSCN) at the interface can be experimentally challenging. These challenges include restrictions in accessing the ultraviolet spectral range through transient electronic spectroscopy, where the absorption spectrum of CuSCN is located. Time-resolved vibrational spectroscopy solves this problem by tracking marker modes at specific frequencies and allowing direct access to dynamical information at the molecular level at donor–acceptor interfaces in real time. This study uses photoabsorber PM6 (poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)-benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione))]) as a model system to explore and decipher the hole transfer dynamics of CuSCN using femtosecond (fs) mid-infrared (IR) spectroscopy. The time-resolved results indicate that excited PM6 exhibits a sharp vibrational mode at 1599 cm–1 attributed to the carbonyl group, matching the predicted frequency position obtained from time-dependent density functional theory (DFT) calculations. The fs mid-IR spectroscopy demonstrates a fast formation (<168 fs) and blue spectral shift of the CN stretching vibration from 2118 cm–1 for CuSCN alone to 2180 cm–1 for PM6/CuSCN, confirming the hole transfer from PM6 to CuSCN. The short interfacial distance and high frontier orbital delocalization obtained from the interfacial DFT models support a coherent and ultrafast regime for hole transfer. These results provide direct evidence for hole injection at the interface of CuSCN for the first time using femtosecond mid-IR spectroscopy and serve as a new investigative approach for interfacial chemistry and solar cell communities.

Article

Selective Mono-Defluorinative Cross-Coupling of Trifluoromethyl arenes via Multiphoton Photoredox Catalysis

(Wiley, 2024-04-04) Jia, Jiaqi; Zhumagazy, Serik; Zhu, Chen; Lee, Shao-Chi; Alsharif, Salman; Yue, Huifeng; Rueping, Magnus; Catalysis Research Center; KAUST Catalysis Center (KCC); Physical Sciences and Engineering; Physical Science and Engineering (PSE) Division; Chemistry; Chemical Science Program; Key Laboratory of Molecule Synthesis and Function Discovery (Fujian Province University) College of Chemistry Fuzhou University Fuzhou 350108

A new cross-coupling of trifluoromethyl arenes has been realized via multiphoton photoredox catalysis. Trifluoromethyl arenes were demonstrated to undergo selective mono-defluorinative alkylation under mild reaction conditions providing access to a series of valuable α,α-difluorobenzylic compounds. The reaction shows broad substrate scope and general functional group tolerance. In addition to the electron-deficient trifluoromethyl arenes that are easily reduced to the corresponding radical anion, more challenging electron-rich substrates were also successfully applied. Steady-State Stern-Volmer quenching studies indicated that the trifluoromethyl arenes were reduced by the multiphoton excited Ir-based photocatalyst.

Article

In Situ Growth of (−201) Fiber-Textured β-Ga2O3 Semiconductor Tape for Flexible Thin-Film Transistor

(Wiley, 2024-04-04) Tang, Xiao; Zhao, Yue; Li, Kuang-Hui; Liu, Chen; Faber, Hendrik; Babatain, Wedyan; Liao, Che-Hao; Yuvaraja, Saravanan; Khandelwal, Vishal; Chettri, Dhanu; Cao, Haicheng; Lu, Yi; Wang, ChuanJu; Anthopoulos, Thomas D.; Zhang, Xixiang; Li, Xiaohang; Advanced Semiconductor Laboratory Electrical and Computer Engineering Program CEMSE Division King Abdullah University of Science and Technology (KAUST) Thuwal 23955–6900 Saudi Arabia; Division of Physical Science and Engineering (PSE) King Abdullah University of Science and Technology (KAUST) Thuwal 23955–6900 Saudi Arabia; KAUST Solar Center (KSC) King Abdullah University of Science and Technology (KAUST) Thuwal 23955–6900 Saudi Arabia; MMH Labs Electrical and Computer Engineering King Abdullah University of Science and Technology (KAUST) Thuwal 23955–6900 Saudi Arabia; Electrical and Computer Engineering; Electrical and Computer Engineering Program; Computer, Electrical and Mathematical Sciences and Engineering; Computer, Electrical and Mathematical Science and Engineering (CEMSE) Division; Applied Physics; Physical Sciences and Engineering; Physical Science and Engineering (PSE) Division; KAUST Solar Center; KAUST Solar Center (KSC); Material Science and Engineering; Material Science and Engineering Program; School of Electronic Information and Electrical Engineering Shanghai Jiao Tong University Shanghai 200240 China

High-temperature in situ growth of Ga2O3 thin film on flexible substrates for flexible/portable electronic devices is never realized because the conventional polymer substrates cannot meet the thermal-stability requirements. In the research, for the first time, Ga2O3 thin films are directly grown on SiOx/Al2Ox buffered Hastelloy substrates. With pulsed laser deposition under high temperature, as-grown Ga2O3 thin films have a fabric texture with a preferred out-of-plane orientation along (−201) and a good field-effect mobility of 18.07 cm2 V−1 s−1. The Ga2O3 coated tape is patterned with transistor arrays and exhibited good performance homogeneity. The representative transistor devices have a threshold voltage of ≈−2.75 V and a breakdown voltage of 116 V measured under a −20 V gate voltage. Moreover, the tape transistors also have good mechanical robustness. The transistors’ good electrical performance, high uniformity, and mechanical robustness suggest that the in situ deposition technique using Hastelloy tape is promising for fabricating various flexible Ga2O3 channeled electronic circuits. Furthermore, it is believed that this technique can be extended to other flexible semiconductor devices that require high-temperature processing.

Article

Deep learning-based extraction of surface wave dispersion curves from seismic shot gathers

(Wiley, 2024-04-03) Chamorro, Danilo; Zhao, Jiahua; Birnie, Claire Emma; Staring, Myrna; Fliedner, Moritz; Ravasi, Matteo; King Abdullah University of Science and Technology Thuwal Saudi Arabia; Ali I. Al-Naimi Petroleum Engineering Research Center; Ali I. Al-Naimi Petroleum Engineering Research Center (ANPERC); Physical Sciences and Engineering; Physical Science and Engineering (PSE) Division; Earth Science and Engineering; Earth Science and Engineering Program; School of Science Department of Geosciences University of Padova Padua Italy; Fugro Nootdorp Netherlands

Multi-channel analysis of surface waves is a seismic method employed to obtain useful information about shear-wave velocities in the near surface. A fundamental step in this methodology is the extraction of dispersion curves from dispersion spectra, with the latter usually obtained by applying specific processing algorithms onto the recorded shot gathers. Although the extraction process can be automated to some extent, it usually requires extensive quality control, which can be arduous for large datasets. We present a novel approach that leverages deep learning to identify a direct mapping between seismic shot gathers and their associated dispersion curves (both fundamental and first higher order modes), therefore by-passing the need to compute dispersion spectra. Given a site of interest, a set of 1D compressional and shear velocities and density models are created using prior knowledge of the local geology; pairs of seismic shot gathers and Rayleigh-wave phase dispersion curves are then numerically modelled and used to train a simplified residual network. The proposed approach is shown to achieve high-quality predictions of dispersion curves on a synthetic test dataset and is, ultimately, successfully deployed on a field dataset. Various uncertainty quantification and convolutional neural network visualization techniques are also presented to assess the quality of the inference process and better understand the underlying learning process of the network. The predicted dispersion curves are inverted for both the synthetic and field data; in the latter case, the resulting shear-wave velocity model is plausible and consistent with prior geological knowledge of the area. Finally, a comparison between the manually picked fundamental modes with the predictions from our model allows for a benchmark of the performance of the proposed workflow.

Article

Multimaterial Fibers with Nanoemitters Enable Conformal X-ray Imaging with 3D Printed and Woven Scintillators

(American Chemical Society (ACS), 2024-04-03) Saidzhonov, Bedil M.; Yorov, Khursand E.; Yuan, Peng; Nematulloev, Saidkhodzha; Karluk, Azimet; Ahmad, Taimoor; Mohammed, Omar F.; Bakr, Osman M.; Bayindir, Mehmet; KAUST Catalysis Center (KCC), Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955−6900, Saudi Arabia; Catalysis Research Center; KAUST Catalysis Center (KCC); Physical Sciences and Engineering; Physical Science and Engineering (PSE) Division; Chemistry; Chemical Science Program; Material Science and Engineering; Material Science and Engineering Program; Advanced Membranes and Porous Materials Center; Advanced Membranes and Porous Materials Research Center; Center for Hybrid Nanostructures, University of Hamburg, Hamburg 22761, Germany

Multimaterial luminescent fibers featuring integrated organic, inorganic, or hybrid nanoemitters are essential elements within a multitude of photonic systems. These systems encompass critical applications, such as single photon sources, high-energy radiation and particle sensors, and wireless optical communication networks. However, the integration of highly efficient luminescent nanomaterials into fibers with predefined geometries, materials, and functionalities remains challenging. This work reports on a process for fabricating indefinitely long multimaterial polymer fibers that can be doped with different organic-inorganic hybrid emitters, such as Cs3Cu2I5 nanoparticles, Cu2I2 nanoclusters, and Mn-doped Cs4CdBi2Cl12 phosphors. This versatility allows for the creation of fibers with tunable emission colors, which enable the realization of large-area, high-performance scintillation surfaces by additive manufacturing, weaving, or rolling. These conformal scintillator screens have been used to demonstrate X-ray imaging of nonplanar complex shapes without the image distortion and resolution degradation associated with rigid planar scintillator configurations. Additive manufacturing of sophisticated three-dimensional scintillators with nanoemitters offers opportunities for personalized medical imaging platforms, particularly for breast cancer screening, as well as applications in large-area high-energy radiation and particle detection.