For almost sixty years, solar energy for space applications has relied on inorganic photovoltaics, evolving from solar cells made of single crystalline silicon to triple junctions based on germanium and III-V alloys. The class of organic-based photovoltaics, which ranges from all-organic to hybrid perovskites, has the potential of becoming a disruptive technology in space applications, thanks to the unique combination of appealing intrinsic properties (e.g. record high specific power, tunable absorption window) and processing possibilities. Here, we report on the launch of the stratospheric mission OSCAR, which demonstrated for the first time organic-based solar cell operation in extraterrestrial conditions. This successful maiden flight for organic-based photovoltaics opens a new paradigm for solar electricity in space, from satellites to orbital and planetary space stations.Nevertheless, already in the fields of aerospace[3] and of organic and hybrid semiconductors [4,5], the specific power (W/kg) was proposed as a valid figure of merit to evaluate PV technologies for space missions. In this regard, Organic Solar Cells (OSCs) and hybrid organic-inorganic Perovskite Solar Cells (PSCs) -termed together as HOPV, Hybrid and Organic PhotoVoltaicsgreatly outperform their inorganic counterparts [4,5]. They represent two novel branches of PV technologies, which saw their rise during the last decade (last few years in the case of PSCs) thanks to their potentially very low production costs. The high absorbance of the photo-active layers in HOPVs allows for efficient light collection within a few hundred nanometers of material, which leads to thicknesses one or two orders of magnitude lower than those of inorganic thin PVs. The rest of the layers making up the solar cell stacks are either as thin as or thinner than the absorbers, and the only thickness (and hence mass) limitation comes from substrate and encapsulation, which can consist of micrometers thick flexible plastic foil [4,5]. The specific power reached to date for perovskite (23 kW/kg) [4] and organic (10 kW/kg)[5] solar cells is thus over 20

We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) interlaboratory study on the measurement of composition in organic depth profiling. Layered samples with known binary compositions of Irganox 1010 and either Irganox 1098 or Fmoc-pentafluoro-l-phenylalanine in each layer were manufactured in a single batch and distributed to more than 20 participating laboratories. The samples were analyzed using argon cluster ion sputtering and either X-ray photoelectron spectroscopy (XPS) or time-of-flight secondary ion mass spectrometry (ToF-SIMS) to generate depth profiles. Participants were asked to estimate the volume fractions in two of the layers and were provided with the compositions of all other layers. Participants using XPS provided volume fractions within 0.03 of the nominal values. Participants using ToF-SIMS either made no attempt, or used various methods that gave results ranging in error from 0.02 to over 0.10 in volume fraction, the latter representing a 50% relative error for a nominal volume fraction of 0.2. Error was predominantly caused by inadequacy in the ability to compensate for primary ion intensity variations and the matrix effect in SIMS. Matrix effects in these materials appear to be more pronounced as the number of atoms in both the primary analytical ion and the secondary ion increase. Using the participants' data we show that organic SIMS matrix effects can be measured and are remarkably consistent between instruments. We provide recommendations for identifying and compensating for matrix effects. Finally, we demonstrate, using a simple normalization method, that virtually all ToF-SIMS participants could have obtained estimates of volume fraction that were at least as accurate and consistent as XPS.

In this work, Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), Principal Component Analysis (PCA) and X-ray Photoelectron Spectroscopy (XPS) have been used to characterize the surface chemistry of gold substrates before and after functionalization with thiol-modified glucose self-assembled monolayers and subsequent biochemical specific recognition of maltose binding protein (MBP). The results indicate that the surface functionalization is achieved both on flat and nanoparticles gold substrates thus showing the potential of the developed system as biodetection platform. Moreover, the method presented here has been found to be a sound and valid approach to characterize the surface chemistry of nanoparticles functionalized with large molecules. Both techniques were proved to be very useful tools for monitoring all the functionalization steps, including the investigation of the biological behavior of the glucose-modified particles in the presence of the maltose binding protein.

Carbon-based nanomaterials have attracted much interest during the last decade for biomedical applications. Multimodal imaging probes based on carbon nano-onions (CNOs) have emerged as a platform for bioimaging because of their cell-penetration properties and minimal systemic toxicity. Here, we describe the covalent functionalization of CNOs with fluorescein and folic acid moieties for both imaging and targeting cancer cells. The modified CNOs display high brightness and photostability in aqueous solutions and their selective and rapid uptake in two different cancer cell lines without significant cytotoxicity was demonstrated. The localization of the functionalized CNOs in late-endosomes cell compartments was revealed by a correlative approach with confocal and transmission electron microscopy. Understanding the biological response of functionalized CNOs with the capability to target cancer cells and localize the nanoparticles in the cellular environment, will pave the way for the development of a new generation of imaging probes for future biomedical studies.

Stability is one of the key challenges for industrial scale commercialization of perovskite solar cells. In this work, a degradation mechanism that depends on materials and bias conditions of the device during light‐soaking is proposed. The observed degradation is linked to the additive 4‐tert‐butyl pyridine (tBP), crucial to the hole transport layer of most perovskite solar cells, and gold. This conclusion is reached through the statistical analysis of multiple compositional profiles of light‐soaked and nonlight‐soaked devices and by selective replacement of material layers of the device. Moreover, the rate of the light‐induced degradation is enhanced by operation at forward bias, which is required for power generation. Thus, this work stresses the need for the development of transport layers that do not require tBP, and to replace gold to produce high‐performing devices that are also stable under operating conditions.

A strategy for creating a general-purposes surface functionalization platform is reported, based on direct attachment of phosphate groups onto hydroxylated surfaces and subsequent formation of a terpyridine-based monolayer. Such a platform is suitable for the construction, onto technologically relevant oxide surfaces, of single- and multilayer structures of interest in technological applications. In particular, the paper describes the successful attachment of 4-(2,2':6',2''-terpyridine-4-yl)benzenephosphonic acid (1, PPTP) onto a SiO(2) surface previously functionalized by means of Zr-phosphate groups. Two alternative anchoring strategies of the PPTP were explored: (i) a direct one-step way, implying no protection of terpyridinic functionality, and (ii) a three-step way, implying protection and successive deprotection of this group. It was found that, in the first case, the PPTP ligand anchoring to the Zr-containing phosphate layer takes place by means of terpyridinic group. At variance of this, in the second case, due to the protection of the terpyridinic functionality, the anchoring process takes place through the phosphonic group, making the terpyridinic moiety available for further reactions, i.e., multilayer constructs. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to study the functionalized surfaces, providing information on coverage, chemical structure, and stoichiometry of the various functionalized layers and, among the others, clear evidence of the PPTP linkage and orientation.

Filamentous cable bacteria display unrivalled long-range electron transport, generating electrical currents over centimeter distances through a highly ordered network of fibers embedded in their cell envelope. The conductivity of these periplasmic wires is exceptionally high for a biological material, but their chemical structure and underlying electron transport mechanism remain unresolved. Here, we combine high-resolution microscopy, spectroscopy, and chemical imaging on individual cable bacterium filaments to demonstrate that the periplasmic wires consist of a conductive protein core surrounded by an insulating shell layer. The core proteins contain a sulfur-ligated nickel cofactor, and conductivity decreases when nickel is oxidized or selectively removed. The involvement of nickel as the active metal in biological conduction is remarkable, and suggests a hitherto unknown form of electron transport that enables efficient conduction in centimeter-long protein structures.

Ion beam depth profiling is increasingly used to investigate layers and interfaces in complex multilayered devices, including solar cells. This approach is particularly challenging on hybrid perovskite layers and perovskite solar cells because of the presence of organic/inorganic interfaces requiring the fine optimization of the sputtering beam conditions. The ion beam sputtering must ensure a viable sputtering rate on hard inorganic materials while limiting the chemical (fragmentation), compositional (preferential sputtering) or topographical (roughening and intermixing) modifications on soft organic layers. In this work, model (Csx(MA0.17FA0.83)100−xPb(I0.83Br0.17)3/cTiO2/Glass) samples and full mesoscopic perovskite solar cells are profiled using low-energy (500 and 1000 eV) monatomic beams (Ar+ and Cs+) and variable-size argon clusters (Arn+, 75 < n < 4000) with energy up to 20 keV. The ion beam conditions are optimized by systematically comparing the sputtering rates and the surface modifications associated with each sputtering beam. X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and in-situ scanning probe microscopy are combined to characterize the interfaces and evidence sputtering-related artifacts. Within monatomic beams, 500 eV Cs+ results in the most intense and stable ToF-SIMS molecular profiles, almost material-independent sputtering rates and sharp interfaces. Large argon clusters (n > 500) with insufficient energy (E < 10 keV) result in the preferential sputtering of organic molecules and are highly ineffective to sputter small metal clusters (Pb and Au), which tend to artificially accumulate during the depth profile. This is not the case for the optimized cluster ions having a few hundred argon atoms (300 < n < 500) and an energy-per-atom value of at least 20 eV. In these conditions, we obtain (i) the low fragmentation of organic molecules, (ii) convenient erosion rates on soft and hard layers (but still different), and (iii) constant molecular profiles in the perovskite layer, i.e., no accumulation of damages.