The floating catalyst chemical vapor deposition (FCCVD) method for producing single‐walled carbon nanotubes (SWNTs) has demonstrated great potential in transparent conductive film (TCF) application. In FCCVD, reducing the concentration of carbon nanotubes (CNTs) is a well‐agreed method of improving the conductivity of SWNT TCF, achieved by producing thinner and longer CNT bundles. However, this method decreases the yield dramatically, which has persisted throughout the TCF development. Here, the production of large‐diameter double‐walled CNT (DWNT) TCFs via FCCVD is reported, which overcomes the tradeoff between performance and yield. These TCFs of DWNTs with an average diameter of ≈4 nm have a low sheet resistance of 35 Ω sq−1 at 90% transmittance. The conductivity here aligns with the best‐performing SWNT TCFs reported to date, showing a production yield greater than two orders of magnitude. The main factor contributing to the high performance and yield is considered to be the large tube diameter, which greatly improves the yield threshold of CNT bundling and leads to long tube length and unique junctions broadening. Moreover, the application of DWNT TCFs in perovskite solar cells exhibits a power conversion efficiency of 17.4%, which has not been reported yet in indium‐free CNT‐based solar cells.
We investigate the electron-positron pair cascade taking place in the magnetosphere of a rapidly rotating black hole. Because of the spacetime frame dragging, the Goldreich-Julian charge density changes sign in the vicinity of the event horizon, which leads to an occurrence of a magnetic-field aligned electric field, in the same way as the pulsar outer-magnetospheric accelerator. In this lepton accelerator, electrons and positrons are accelerated in the opposite directions, to emit copious gamma-rays via the curvature and inverse-Compton processes. We examine a stationary pair cascade, and show that a stellar-mass black hole moving in a gaseous cloud can emit a detectable very-high-energy flux, provided that the black hole is extremely rotating and that the distance is less than about 1 kpc. We argue that the gamma-ray image will have a point-like morphology, and demonstrate that their gamma-ray spectra have a broad peak around 0.01-1 GeV and a sharp peak around 0.1 TeV, that the accelerators become most luminous when the mass accretion rate becomes about 0.01% of the Eddington rate, and that the predicted gamma-ray flux little changes in a wide range of magnetospheric currents. An implication of the stability of such a stationary gap is discussed.
Perovskite solar cells (PSCs) are considered to be one of the most promising solar energy harvesters owing to their high power conversion efficiency (PCE). To increase their PCE even further, additives are used; however, some of these additives pose certain disadvantages, which limit their applications to PSCs. Therefore, in this study, the nature‐inspired ecofriendly M13 bacteriophage is genetically engineered to maximize its performance as a perovskite crystal growth template and as a passivator for PSCs. The genetic manipulation of the M13 bacteriophage enhances the Lewis coordination between the perovskite materials and single‐stranded virus by amplifying a designated amino acid group. Among the 20 types of amino acids, lysine (Lys or K), arginine (Arg or R), and methionine (Aug or M) exhibit the strongest interaction with the perovskite materials. Results suggest that the K‐amplified genetically engineered M13 bacteriophage is the most effective. The K‐type M13 virus‐inoculated PSCs yield a PCE of 23.6% in the laboratory. This device, when taken to a national laboratory for verification, exhibits a certified forward and reverse bias‐combined efficiency (22.3%), which, to the best of the authors’ knowledge, is one of the highest efficiencies reported among the biomaterial‐based PSCs.
Designing an efficient and stable hole transport layer (HTL) material is one of the essential ways to improve the performance of organic–inorganic perovskite solar cells (PSCs).
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