Manipulating the Crystallization of Tin Halide Perovskites for Efficient Moisture-to-Electricity Conversion.

Manipulating the crystallization of perovskite in thin films is essential for the fabrication of any thin-film-based devices. Fabricating tin-based perovskite films from solution poses difficulties because tin tends to crystallize faster than the commonly used lead perovskite. To achieve optimal device performance in solar cells, the preferred method involves depositing tin perovskite under inert conditions using dimethyl sulfoxide (DMSO), which effectively retards the formation of the tin-bromine network, which is crucial for perovskite assembly. We found that under ambient conditions, a DMSO-based tin perovskite salt solution resulted in the formation of a two-phase system, SnBr4(DMSO)2 and MABr, whereas a dimethylformamide-based solution resulted in the formation of vacancy-ordered double perovskite MA2SnBr6. Humidity is known to solvate MABr to form the solvated ions, and so we used the two-phase system for the application in moisture to electricity conversion. The importance of the presence of the scaffold can be seen with the negligible power output from the vacancy-ordered double perovskite obtained with MA2SnBr6. We have fabricated a device with two-phase system that can generate an open-circuit potential of 520 mV and a short-circuit current density of 30.625 µA/cm2 at 85% RH. Also, the device charges a 10 µF capacitor from 150 mV at 51% RH to 500 mV at 85% RH in 6 s at a rate of 52.5 mV/s. Moreover, the output can be scaled by connecting devices in series and parallel configurations. A 527 nm green LED was powered by connecting five devices in series at 75% RH. This indicates a potential for utilizing these moisture-to-electricity conversion devices in powering low-energy requirement devices.

Self-powered humidity sensors based on zero-dimensional perovskite-like structures with fast response and high stability.

With the rapid development of technology, the development of self-powered sensors has garnered significant attention. The importance of monitoring humidity has grown significantly in various technological contexts, from environmental monitoring to biomedical applications. In this work, we have fabricated a low-cost and self-powered humidity sensor using zero-dimensional perovskite-like structures. Switching tests at different relative humidity levels have shown that the zero-dimensional perovskites have visible coloration at high humidities and discoloration upon reducing the humidity. The humidity sensor was fabricated by spin coating the zero-dimensional perovskites on a patterned fluorine doped tin oxide (FTO) substrate and the sensor not only shows high response values of around 500 mV and few micro amperes of short circuit current densities, but also shows good cycling performance and stability. Also high selectivity to humidity is observed in comparison to different gases and volatile organic compounds. The high selectivity to humidity arises due to the fact that the exclusion of MAI from the MA4PbI6 strucuture does not happen with all the other analytes which has been confirmed from the XRD studies. In addition, due to the low temperature fabrication they can be deposited on flexible substrates and the sensor displayed excellent resistance to bending and durability. Furthermore, the study explored the humidity monitoring capabilities of this sensor, revealing an outstanding response performance to human respiration. This observation suggests that the sensor holds significant potential for practical applications in the monitoring of human health and environmental conditions. This work paves the way for developing organic-inorganic hybrid perovskite materials for self-powered sensing applications.

Modulation of mitochondria by viral proteins.

Mitochondria are dynamic cellular organelles with diverse functions including energy production, calcium homeostasis, apoptosis, host innate immune signaling, and disease progression. Several viral proteins specifically target mitochondria to subvert host defense as mitochondria stand out as the most suitable target for the invading viruses. They have acquired the capability to control apoptosis, metabolic state, and evade immune responses in host cells, by targeting mitochondria. In this way, the viruses successfully allow the spread of viral progeny and thus the infection. Viruses employ their proteins to alter mitochondrial dynamics and their specific functions by a modulation of membrane potential, reactive oxygen species, calcium homeostasis, and mitochondrial bioenergetics to help them achieve a state of persistent infection. A better understanding of such viral proteins and their impact on mitochondrial forms and functions is the main focus of this review. We also attempt to emphasize the importance of exploring the role of mitochondria in the context of SARS-CoV2 pathogenesis and identify host-virus protein interactions.

ZnX2 mediated post-synthetic transformation of zero dimensional Cs4PbBr6 nanocrystals for opto-electronic applications.

Herein we demonstrate a facile approach for the synthesis of all inorganic cesium lead halide perovskite nanocrystal composites CsPbX3 (X = Cl, Br, I) with high quantum yield by post-synthetic modulation of zero dimensional Cs4PbBr6 nanocrystals with ZnX2 salts. The transformation of Cs4PbBr6 nanocrystals into CsPbBr3 takes place in two steps, the first step being the surface modification of the Cs4PbBr6 nanocrystals with Zn2+ ions and the second step being extraction of CsBr by the Zn2+ ions resulting in the formation of composite Cs4PbBr6/CsPbBr3 nanocrystals. The transformed composite nanocrystals were found to have a PL QY exceeding 90% and the shape of the nanocrystals also changed from hexagonal to cubic shaped. Owing to the highly ionic nature of the nanocrystals, complete anion exchange could be also realized using ZnI2 salt. In the case of the iodide post-treated samples, nanorods were obtained which exhibited bright red photoluminescence. Photodetectors based on the ZnI2 treated Cs4PbBr6 NCs were fabricated, and the photodetectors exhibited a high on/off ratio with a fast response time. The excellent optoelectronic properties make this treatment versatile for a wide range of functional optoelectronic devices like light emitting diodes and photovoltaic devices.