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Atomic-scale examination of lead halide perovskites is currently a subject of growing interest for applications in the optimization of perovskite-based photovoltaic and optoelectronic devices. While transmission electron microscopy (TEM) is a powerful tool to characterize these electron-sensitive materials at the atomic scale, it induces structural and chemical modifications along with other undesirable artifacts. Here, we investigate the phase stability of nominally Cu-doped CsPbI3 nanocrystals, with enhanced structural stability as compared to their pristine counterparts, against electron irradiation using high-resolution TEM at ambient conditions. Our findings reveal a significant transformation from the cubic to the orthorhombic phase at a dose of ∼3 × 103 e–/Å2. Analysis of the beam energy deposited per unit cell, along with the evolution of lattice energy with varying cell dimensions, as obtained from density functional theory, provides valuable insights into the mechanisms governing the beam-induced phase decomposition process, corroborated by the phonon dispersion of the system, which is not yet reported. At a critical dose of ∼1.68 × 106 e–/Å2, the lattice undergoes complete and irreversible degradation. Thus, our study demonstrates real-time in situ beam-induced phase decomposition in Cu-doped CsPbI3 for the first time, with an estimation of the electron dose limits below which beam-induced alterations are minimal, allowing accurate imaging and analysis of perovskites. [ABSTRACT FROM AUTHOR]

For GNSS Real-Time Kinematic (RTK), the reference Base receiver operating at a precise location together with the wirelessly connected Rover receiver(s) provide(s) high-quality real-time position solutions. This work shows the potential of compact, low-cost, single-frequency (CLS) GNSS modules as the RTK Rover up to large baseline distances. A combination of the uBLOX M8T CLS module and the Tallysman TW2710 patch antenna is used in single and hybrid GNSS combinations for short-to-long single-baseline lengths with the open-source RTKLib as the processing software. The results show that, for up to 288 km baseline distance, GPS, GLONASS and Galileo standalone operation provides below 1, 3 and 2 m precisions, respectively and sub-0.5 m precision is achieved for GPS+GLONASS+Galileo and GPS+Galileo+QZSS operations. The work shows the advantages of CLS modules as Rover those exploits the multi-constellation signal availability from India using open-source RTK processing software for reduction of the overall RTK infrastructure cost. [ABSTRACT FROM AUTHOR]

Global Navigation Satellite System (GNSS) sensors are increasingly considered as major sources of precise Position, Navigation, and Timing (PNT) information. Android-based smartphones contain inbuilt GNSS sensors, and they now contribute to a major global GNSS market segment. Various hardware and Android-based applications (App) developments are witnessed to best exploit the current multi-constellation, multi-frequency GNSS environment. Since Android version 7.0 (Nougat) and Location Application Programming Interface (API) 24, recording GNSS raw data in the smartphone became possible. This paper describes the potential of commercial Smartphones and reviews the capabilities of Android Apps for cost-efficient GNSS measurements for the geospatial community and a novel classification of the Apps based on their capabilities and usability. Results on the positioning capability of common smartphones using real-time data show the achievable modest solution precision, and these are suitable for use of the devices in geomatics applications, improved App development, and for IoT-based system and infrastructure development. [ABSTRACT FROM AUTHOR]

Hot carrier extraction is crucial for efficient solar energy harvesting, and lead halide perovskite nanocrystals (NCs) are potential candidates for photovoltaic and light-emitting applications. Therefore, swift extraction of hot carriers is an immediate requirement to improve the energy conversion efficiency, which need longer thermalization time. To address this issue, we synthesized nominally Cu-doped CsPbI3 NCs with enhanced structural and optical characteristics compared to undoped CsPbI3 NCs. We investigated the hot carrier dynamics in both the NCs at different fluences using ultrafast transient absorption spectroscopy. Interestingly, we observed very fast thermalization at higher fluences that indicated breaking of the phonon bottleneck. On the contrary, doped NCs preserved the effects and decayed over a longer period of time possibly due to increase in size and introduction of shallow trap states of Cu 3d and Cu 4s electrons in the conduction band, as computed using density functional theory. Notably, as the carrier–carrier interaction increased, we observed a dominating bandgap renormalization in the doped system compared to the undoped system. Overall, our studies improve the understanding of Cu doping in enhancing the hot carrier dynamics in perovskites and open possibilities for further investigation in the quantum phenomenon of these materials. [ABSTRACT FROM AUTHOR]

Global Navigation Satellite System (GNSS) uses Precise Point Positioning (PPP) technique to find out accurate geolocation information of any point. Generally, costly, geodetic GNSS receivers are used for PPP. This manuscript presents the results of studies on the usability of commercial, compact, cost-effective GNSS modules with commercial antennas for PPP in comparison to commonly used geodetic, costly receivers from India, which is a excellent location for GNSS use. Compact GNSS modules from two manufacturers are used in the study, and the encouraging results show the clear advantage of cost, size, and power requirements of such modules. The modules provide sub-cm horizontal solution accuracy which is very similar to those obtained using geodetic receivers, and around 20 cm accuracy in the vertical coordinate, which is slightly inferior to the results provided by the geodetic reveivers. Results of this novel study would be useful for implementing cost-efficient GNSS PPP in real life, in highly demanding geodetic applications including CORS establishment and PPP.

Utilizing the remarkably high light absorption and long carrier diffusion length of inorganic perovskites, superior performance self‐powered broadband photodetectors using the vertical heterojunction of cesium lead iodide (CsPbI3) nanocrystals (NCs) and zinc oxide (ZnO) films on a flexible platform are reported. Here, the pure cubic or α‐phase of as‐synthesized CsPbI3 NCs facilitate the novelty of the present work in terms of their enhanced structural stability suitable for optical applications. The α‐CsPbI3/ZnO device exhibits superior performance with photoresponsivity of ≈8.2 AW−1, ON/OFF ratio of ≈2.4 × 104, and specific detectivity up to ≈1.4 × 1012 Jones. Furthermore, the piezo‐phototronic effect of ZnO has been exploited to enhance the device performance by utilizing the compressive strain‐induced piezoelectric charges for modulating the generation, separation, and transportation of charge carriers. By introducing an approximate −0.042% compressive strain in the hybrid heterostructure, the enhancement of photocurrent, spectral responsivity, and specific detectivity of the detector by ≈619%, ≈536%, and ≈506%, respectively, under visible light illumination has been successfully achieved. This work not only presents an inventive method for improving the performance of perovskite photodetectors through interface engineering, but it also provides a thorough understanding of the piezo‐phototronic effect on optoelectronic devices. [ABSTRACT FROM AUTHOR]

Global Navigation Satellite System (GNSS) provides precise Position, Velocity, and Timing (PVT) information. Various types of receivers of varying cost and complexity are used for collection and use of GNSS data. Currently, cost-effective, compact, low power consuming, multi-constellation enabled, single, or dual-frequency GNSS modules are being increasingly available having the capability of providing modest position solution accuracy. This paper presents the results of GPS, BeiDou, and GPS + BeiDou hybrid positioning capabilities of few commercially available modules based on systematic analysis from data collected during two time periods from two locations of India using geodetic and commercial patch antennas w.r.t. the reference points created through PPP (Precise Point Positioning). The results are compared with those provided a survey-grade GNSS receiver. It is witnessed that, selected single frequency module can provide 3-4m 2DRMS (Distance Root Means Square) precision and their dual frequency counterparts can provide 2DRMS solution precision around 3 m in GPS-only operation, around 7 m in BeiDou-only operation and around 3.5 m in case of GPS + BeiDou hybrid operation. The performance of the compact modules clearly presents the cost-performance benefit of the compact modules for real-time applications and the results of this study would help in understanding the capabilities of these modules for mass-market applications. [ABSTRACT FROM AUTHOR]

Although α‐CsPbI3 is regarded as an attractive optical luminophore, it is readily degraded to the optically inactive δ‐phase under ambient conditions. Here, we present a simple approach to revive degraded ("optically sick") α‐CsPbI3 through "medication" with thiol‐containing ligands. The effect of different types of thiols is systematically studied through optical spectroscopy. The structural reconstruction of degraded α‐CsPbI3 nanocrystals to cubic crystals in the presence of thiol‐containing ligands is visualized through high‐resolution transmission electron microscopy and supported by X‐ray diffraction analysis. We found that 1‐dodecanethiol (DSH) effectively revives degraded CsPbI3 and results in high immunity towards moisture and oxygen, hitherto unreported. DSH facilitates the passivation of surface defects and etching of degraded Cs4PbI6 phase, thus reverting them back to the cubic CsPbI3 phase, leading to enhanced PL and environmental stability. [ABSTRACT FROM AUTHOR]