The area of thin-film photovoltaics has been overwhelmed by organometal halide perovskites. Unfortunately, serious stability concerns arise with perovskite solar cells. For example, methyl-ammonium lead iodide is known to decompose in the presence of water and, more severely, even under inert conditions at elevated temperatures. Here, we demonstrate inverted perovskite solar cells, in which the decomposition of the perovskite is significantly mitigated even at elevated temperatures. Specifically, we introduce a bilayered electron-extraction interlayer consisting of aluminium-doped zinc oxide and tin oxide. We evidence tin oxide grown by atomic layer deposition does form an outstandingly dense gas permeation barrier that effectively hinders the ingress of moisture towards the perovskite and—more importantly—it prevents the egress of decomposition products of the perovskite. Thereby, the overall decomposition of the perovskite is significantly suppressed, leading to an outstanding device stability.

In recent years, the search for new electrode materials for rechargeable Li-ion batteries has undergone a drastic shift toward nanomaterials. A similar tendency is expected to occur for the conceptually similar Na-ion batteries. Due to very short internal diffusion paths, nanoscale materials are far less limited by their ionic or electronic conductivities than their bulk counterparts. Nanomaterials can also withstand much greater mechanical deformation during charge/discharge cycling. Overall, these favorable effects significantly enlarge the variety of inorganic compounds that can be used as Li and Na ion storage media. Herein, we discuss the perspectives of a specific family of nanomaterialsmonodisperse colloidal nanocrystals and nanoparticlesfor controlling and studying the effects of size, composition, and morphology on electrochemical properties. Despite clear scientific advantages, commercialization of such nanomaterials is presently hampered by their high cost of synthesis, owing to the use of organic solvents and coordination compounds.

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low fi ll-factors (FFs) and overall low power conversion efficiency are found. This phenomenon is frequently referred to as "light-soaking" issue. [ 31,32 ] Development of charge extraction materials that do not rely on UV activation has been identifi ed to be of paramount importance to achieve highly effi cient and long-term stable devices. [ 33,34 ] In this sense, doped metaloxide EELs, e.g., Al:ZnO, [ 31,35,36 ] have been shown to mitigate the need for UV activation. While there are several reports of OSCs incorporating ZnO-based EELs in organic solar cells, which show a promising "shelf-life," [ 37 ] photoinduced shunts have been found to occur in the devices upon illumination "in actual operation." [38][39][40] Analogous to the case of the light activation discussed above, these photoinduced shunts are associated with the illumination by UV light (i.e., hν > E g ). As a result, a signifi cantly lowered shunt resistance along with a substantial decay of the FF and V oc is typically found to occur within minutes of illumination. The origin of this photoinduced shunt has been related to the UV-induced desorption of chemisorbed oxygen at the ZnO surface. [ 38 ] Approaches to modify and thereby to stabilize the ZnO surface range from the use of passivating mole cules [ 41 ] to the evaporation of thin aluminum layers onto the ZnO EEL. [ 39 ] Here, we will show that the photoinduced shunting behavior is a general phenomenon in OSCs comprising "neat or electrically doped" ZnO-based electron extraction layers, i.e., Al:ZnO (AZO) or Ga:ZnO (GZO), and it is found regardless if the EEL is prepared from nanoparticle dispersions or by vacuumbased techniques ( Figure 1 ). The photoinduced shunting of ZnO-based OSCs occurs for devices operated in air or under inert atmosphere, and it can therefore not be avoided by using a proper encapsulation. Moreover, we will show that while the photoinduced shunting is reversible in air, it is irreversible under the exclusion of oxygen. Opposed to ZnO-based EELs, we will demonstrate that the photoinduced shunting and the con-

In this paper we report the influence of stereochemistry on self-organization in the solid state of cyclic dipeptides (CDP) employing two diastereomeric samples cyclo­(l-Tyr-l-Ala), cYA 1, and cyclo­(l-Tyr-d-Ala), cY­(D)­A 2, as models. Both compounds were investigated by means of differential scanning calorimetry (DSC), solid state NMR (SS NMR) spectroscopy, scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), electronic circular dichroism (ECD) spectroscopy, and attenuated total reflectance Fourier transform infrared spectroscopy (ATR–FTIR). It has been found that distinction in chirality of alanine residue causes a significant difference in self-assembling and formation of higher order structures. Sample 1 forms peptide nanotubes (PNT) and nanowires (PNW), while for sample 2 only formation of peptide microtubes (PMT) was observed. Crystal and molecular structures for 1 and 2 were refined using PXRD due to failure in attempts to grow crystals with quality suitable for single crystal studies. Both compounds crystallize in the P21 space group and monoclinic system. The size of the unit cell is highly similar; however small differences in alignment of water molecules in the hydrophilic channels and geometry of diketopiperazine rings were observed. Each technique confirmed high thermal stability of PNT, PNW, and PMT under investigation. The water molecules can be thermally removed from the lattice without destroying the subtle crystal structures of nano- and microdevices. This reversible process observed for sample 2 is a unique feature, rarely occurring for the linear dipeptide devices.

We report a high proton-conducting material prepared for the first time by economical and environmentally-friendly mechanochemistry. Structural elucidation of the material from powder X-ray diffraction data reveals the details of the solid-state reaction. The reaction represents a new synthetic strategy towards materials related to fuel cell technology.

A bilayer of Nb-TiO2 and bathocuproine forms a highly ohmic contact between a wide variety of semiconducting materials and metal electrodes. This enables performance and stability improvements in a range of electronic devices.

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