Interface engineering of organic–inorganic halide perovskite solar cells (PSCs) plays a pivotal role in achieving high power conversion efficiency (PCE). In fact, the perovskite photoactive layer ...needs to work synergistically with the other functional components of the cell, such as charge transporting/active buffer layers and electrodes. In this context, graphene and related two-dimensional materials (GRMs) are promising candidates to tune “on demand” the interface properties of PSCs. In this work, we fully exploit the potential of GRMs by controlling the optoelectronic properties of molybdenum disulfide (MoS2) and reduced graphene oxide (RGO) hybrids both as hole transport layer (HTL) and active buffer layer (ABL) in mesoscopic methylammonium lead iodide (CH3NH3PbI3) perovskite (MAPbI3)-based PSCs. We show that zero-dimensional MoS2 quantum dots (MoS2 QDs), derived by liquid phase exfoliated MoS2 flakes, provide both hole-extraction and electron-blocking properties. In fact, on one hand, intrinsic n-type doping-induced intraband gap states effectively extract the holes through an electron injection mechanism. On the other hand, quantum confinement effects increase the optical band gap of MoS2 (from 1.4 eV for the flakes to >3.2 eV for QDs), raising the minimum energy of its conduction band (from −4.3 eV for the flakes to −2.2 eV for QDs) above the one of the conduction band of MAPbI3 (between −3.7 and −4 eV) and hindering electron collection. The van der Waals hybridization of MoS2 QDs with functionalized reduced graphene oxide (f-RGO), obtained by chemical silanization-induced linkage between RGO and (3-mercaptopropyl)trimethoxysilane, is effective to homogenize the deposition of HTLs or ABLs onto the perovskite film, since the two-dimensional nature of RGO effectively plugs the pinholes of the MoS2 QD films. Our “graphene interface engineering” (GIE) strategy based on van der Waals MoS2 QD/graphene hybrids enables MAPbI3-based PSCs to achieve a PCE up to 20.12% (average PCE of 18.8%). The possibility to combine quantum and chemical effects into GIE, coupled with the recent success of graphene and GRMs as interfacial layer, represents a promising approach for the development of next-generation PSCs.
Highlights • The IS beats the drum for orchestrated organelle motion. • The centrosome polarizes to the IS and organizes a dynamic microtubular network. • Microtubule-dependent vesicular traffic at ...the IS regulates T cell activation. • Mitochondrial network polarization at the IS fine-tunes T cell activation.
In the past few years, several protocols have been reported on the synthesis of CdSe nanoplatelets with narrow photoluminescence (PL) spectrum, high PL quantum efficiency, and short exciton lifetime. ...The corresponding core/shell nanoplatelets are however still mostly based on CdSe/CdS, which possess an extended lifetime and a strong red shift of the band-edge absorption and emission, in accordance with a quasi-type-II band alignment. Here we report on a robust synthesis procedure to grow a ZnS shell around CdSe nanoplatelets at moderate temperatures of 100–150 °C, to improve the optical properties of CdSe nanoplatelets via a type-I core/shell heterostructure. The shell growth is performed under ambient atmosphere, in either toluene or 1,2-dichlorobenzene. The variation of the shell thickness induces a continuous red shift of the PL peak, eventually reaching 611 nm. The PL quantum efficiency is increased compared to the original CdSe cores, with values up to 60% depending on the shell thickness. High-resolution transmission electron microscopy reveals a bending of the nanoplatelets caused by strain due to 12% lattice mismatch between CdSe and ZnS. The present procedure can easily be translated to other core/shell nanocrystals, such as CdSe/CdS and CdSe/CdZnS nanoplatelets.
In this work, we demonstrate the successful application of two-dimensional (2D) materials, i.e., graphene and functionalized MoS2, in perovskite solar cells (PSCs) by interface engineering the ...standard mesoscopic n–i–p structure. The use of 2D materials has the dual role to improve both the stability and the overall power conversion efficiency (PCE) of the PSCs compared to standard devices. The application of 2D materials is successfully extended to large-area perovskite solar modules (PSMs), achieving PCEs of 13.4% and 15.3% on active areas of 108 cm2 and 82 cm2, respectively. This performance results in record-high active area-indexed aperture PCE (AIAPCE) of 1266.5% cm2. In addition, the 2D materials-based PSMs show a stability under a prolonged (>1000 h) thermal stress test at 65 °C (ISOS-D2), representing a crucial advancement in the exploitation of perovskite photovoltaic technology.
PbS nanocrystals are an important narrow-gap material for solar cells and photodetectors. Nevertheless, their application may be limited because device performance can be affected by atmospheric ...conditions. Indeed, the presence of oxygen and/or water can degrade the active layers, possibly leading to device failure. Strategies to address this issue are therefore actively explored. Here we report a solution-processed PbS quantum dot solar cell, consisting of a PbS-silane functionalized reduced graphene oxide (PbS-rGO) layer on top of the PbS absorber film, which enhances device stability, especially when the solar cells are exposed to moisture. Power conversion efficiency (PCE) measurements demonstrate a slower degradation under continuous illumination for solar cells with PbS-rGO. When storing the samples under saturated water vapor, differences are even more remarkable: with PbS-rGO the solar cells essentially maintain their initial PCE, while the PCE of the PbS reference devices is reduced by 50% after 5 days. Scanning electron microscopy, energy dispersive X-ray and X-ray photoelectron spectroscopy reveal the damage to the PbS films and the formation of PbSOx crystals in the PbS reference devices. Such crystals are not observed in the PbS-rGO devices, further supporting the importance of the PbS-rGO barrier layer.
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•We present a solution-processed strategy integrating rGO in PbS solar cells.•We improved long-term stability using rGO, especially at 100% relative humidity.•rGO suppresses the moisture-induced damage to the PbS absorber layer.
The main aim of this study was to validate 500 true-false general-knowledge questions in Russian. These norms are valuable to researchers in many fields, as is shown by the impact and relevance of ...similar norms available in other languages. Although the Russian language is widely spoken, there are no norms available in this language for this type of questions. True-false questions are very useful for measuring semantic memory, among other topics, in neurocognitive studies where there is a trade-off between experimental time and the need for many trials. These types of experimental materials are heavily rooted in cultural background knowledge, making the mere translation from one language to another insufficient. The present research aims to fill this gap. One hundred fifty-five participants answered 500 true-false general knowledge questions split over several consecutive days and three topics: Social Sciences, Natural Sciences, and Culture & Sport. The participants' task was to indicate whether the statements were true or not, as well as the confidence they had in the correctness of their answer. Despite obtaining questions on each of the topics covering all difficulty levels, grouped analyses showed that Social Science's accuracy was higher than for Natural Science's or Culture & Sport questions. In relation to confidence, the grouped perceived difficulty was higher for questions about Culture & Sports when compared with the other two topics. Thus, this study reports and makes available a large pool of Russian true-false general knowledge questions covering different levels of difficulty.
The different cytoskeleton systems and their connecting molecular motors move vesicles and intracellular organelles to shape cells. Polarized cells with specialized functions display an exquisite ...spatio-temporal regulation of both cytoskeletal and organelle arrangements that support their specific tasks. In particular, T cells rapidly change their shape and cellular function through the establishment of cell surface and intracellular polarity in response to a variety of cues. This review focuses on the contribution of the microtubule-based dynein/dynactin motor complex, the tubulin and actin cytoskeletons, and different organelles to the formation of the antigen-driven immune synapse.
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