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1. Screening for electrically conductive defects in thin functional films using electrochemiluminescence

   https://doi.org/10.1039/D3AY00687E  

   Quinn, Harley; Wang, Wenlu; Werner, Jörg G; Brown, Keith A (July 2023, Analytical Methods)

   Multifunctional thin films in energy-related devices often must be electrically insulating where a single nanoscale defect can result in complete device-scale failure. Locating and characterizing such defects presents a fundamental problem where high-resolution imaging methods are needed to find defects, but imaging with high spatial resolution limits the field of view and thus the measurement throughput. Here, we present a novel high-throughput method for detecting sub-micron defects in insulating thin films by leveraging the electrochemiluminescence (ECL) of luminol. Through a systematic study of reagent concentrations, buffers, voltage, and excitation time, we identify optimized conditions at which it is possible to detect sub-micron defects at high-throughput. Extrapolating from the signal to background observed for detecting 440 nm wide lines and 620 nm diameter circles, we estimate the minimum detectable features to be lines as narrow as 2.5 nm in width and pinholes as small as 70 nm in radius. We further explore this method by using it to characterize a nominally insulating phenol film and find conductive defects that are cross-correlated with high-resolution atomic force microscopy to provide feedback to synthesis. Given this assay’s inherent parallelizability and scalability, it is expected to have a major impact on the automated discovery of multifunctional films. 

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2. Alignment of the optical system of the 9.7-m prototype Schwarzchild-Coulder Telescope

   https://doi.org/10.1117/12.2564653  

   Adams, C.~B.~; Alfaro, R.~; G.~Ambrosi, Ambrosi; Ambrosio, M.~; Aramo, C.~; Benbow, W.~; Bertucci, B.~; Bissaldi, E.~; Bitossi, M.~; Boiano, A.~; et al (December 2020, Proceedings Volume 11445, Ground-based and Airborne Telescopes VIII;)

   Marshall, Heather K.; Spyromilio, Jason; Usuda, Tomonori (Ed.)

   The novel 9.7m Schwarzschild-Couder Telescope (SCT), utilizing aspheric dual-mirror optical system, has been constructed as a prototype medium size x-ray telescope for the Cherenkov Telescope Array (CTA) observatory. The prototype SCT (pSCT) is designed to achieve simultaneously the wide (≥ 8°) field of view and the superior imaging resolution (0.067 per pixel) to significantly improve scientific capabilities of the observatory in conducting the sky surveys, the follow-up observations of multi-messenger transients with poorly known initial localization and the morphology studies of x-ray sources with angular extent. In this submission, we describe the hardware and software implementations of the telescope optical system as well as the methods specifically developed to align its complex optical system, in which both primary and secondary mirrors are segmented. The pSCT has detected Crab Nebula in June 2020 during ongoing commissioning, which was delayed due to worldwide pandemic and is not yet completed. Verification of pSCT performance is continuing and further improvement of optical alignment is anticipated. 

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3. Interference, diffraction, and diode effects in superconducting array based on bismuth antimony telluride topological insulator

   https://doi.org/10.1038/s42005-023-01288-9  

   Song, Xiangyu; Suresh_Babu, Soorya; Bai, Yang; Golubev, Dmitry_S; Burkova, Irina; Romanov, Alexander; Ilin, Eduard; Eckstein, James_N; Bezryadin, Alexey (July 2023, Communications Physics)

   Abstract It is well-known in optics that the spectroscopic resolution of a diffraction grating is much better compared to an interference device having just two slits, as in Young’s famous double-slit experiment. On the other hand, it is well known that a classical superconducting quantum interference device (SQUID) is analogous to the optical double-slit experiment. Here we report experiments and present a model describing a superconducting analogue to the diffraction grating, namely an array of superconducting islands positioned on a topological insulator film Bi_0.8Sb_1.2Te₃. In the limit of an extremely weak field, of the order of one vortex per the entire array, such devices exhibit a critical current peak that is much sharper than the analogous peak of an ordinary SQUID. Therefore, such arrays can be used as sensitive absolute magnetic field sensors. A key finding is that the device acts as a superconducting diode, controlled by magnetic field. 

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4. Intrinsic (Trap‐Free) Transistors Based on Epitaxial Single‐Crystal Perovskites

   https://doi.org/10.1002/adma.202205055  

   Bruevich, Vladimir; Kasaei, Leila; Rangan, Sylvie; Hijazi, Hussein; Zhang, Zhenyuan; Emge, Thomas; Andrei, Eva_Y; Bartynski, Robert_A; Feldman, Leonard_C; Podzorov, Vitaly (September 2022, Advanced Materials)

   Abstract The first experimental realization of the intrinsic (not dominated by defects) charge conduction regime in lead‐halide perovskite field‐effect transistors (FETs) is reported. The advance is enabled by: i) a new vapor‐phase epitaxy technique that results in large‐area single‐crystalline cesium lead bromide (CsPbBr₃) films with excellent structural and surface properties, including atomically flat surface morphology, essentially free from defects and traps at the level relevant to device operation; ii) an extensive materials analysis of these films using a variety of thin‐film and surface probes certifying the chemical and structural quality of the material; and iii) the fabrication of nearly ideal (trap‐free) FETs with characteristics superior to any reported to date. These devices allow the investigation of the intrinsic FET and (gated) Hall‐effect carrier mobilities as functions of temperature. The intrinsic mobility is found to increase on cooling from ≈30 cm²V⁻¹s⁻¹at room temperature to ≈250 cm²V⁻¹s⁻¹at 50 K, revealing a band transport limited by phonon scattering. Establishing the intrinsic (phonon‐limited) mobility provides a solid test for theoretical descriptions of carrier transport in perovskites, reveals basic limits to the technology, and points to a path for future high‐performance perovskite electronic devices. 

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5. Eco‐Friendly Solvent Engineered CsPbI _2.77 Br _0.23 Ink for Large‐Area and Scalable High Performance Perovskite Solar Cells

   https://doi.org/10.1002/adma.202310279  

   Abate, Seid_Yimer; Qi, Yifang; Zhang, Qiqi; Jha, Surabhi; Zhang, Haixin; Ma, Guorong; Gu, Xiaodan; Wang, Kun; Patton, Derek; Dai, Qilin (December 2023, Advanced Materials)

   Abstract The performance of large‐area perovskite solar cells (PSCs) has been assessed for typical compositions, such as methylammonium lead iodide (MAPbI₃), using a blade coater, slot‐die coater, solution shearing, ink‐jet printing, and thermal evaporation. However, the fabrication of large‐area all‐inorganic perovskite films is not well developed. This study develops, for the first time, an eco‐friendly solvent engineered all‐inorganic perovskite ink of dimethyl sulfoxide (DMSO) as a main solvent with the addition of acetonitrile (ACN), 2‐methoxyethanol (2‐ME), or a mixture of ACN and 2‐ME to fabricate large‐area CsPbI_2.77Br_0.23films with slot‐die coater at low temperatures (40–50 °C). The perovskite phase, morphology, defect density, and optoelectrical properties of prepared with different solvent ratios are thoroughly examined and they are correlated with their respective colloidal size distribution and solar cell performance. The optimized slot‐die‐coated CsPbI_2.77Br_0.23perovskite film, which is prepared from the eco‐friendly binary solvents dimethyl sulfoxide:acetonitrile (0.8:0.2 v/v), demonstrates an impressive power conversion efficiency (PCE) of 19.05%. Moreover, the device maintains ≈91% of its original PCE after 1 month at 20% relative humidity in the dark. It is believed that this study will accelerate the reliable manufacturing of perovskite devices. 

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