One-Year stable perovskite solar cells by 2D/3D interface engineering

Despite the impressive photovoltaic performances with power conversion efficiency beyond 22%, perovskite solar cells are poorly stable under operation, failing by far the market requirements. Various technological approaches have been proposed to overcome the instability problem, which, while delivering appreciable incremental improvements, are still far from a market-proof solution. Here we show one-year stable perovskite devices by engineering an ultra-stable 2D/3D (HOOC(CH₂)₄NH₃)₂PbI₄/CH₃NH₃PbI₃ perovskite junction. The 2D/3D forms an exceptional gradually-organized multi-dimensional interface that yields up to 12.9% efficiency in a carbon-based architecture, and 14.6% in standard mesoporous solar cells. To demonstrate the up-scale potential of our technology, we fabricate 10 × 10 cm² solar modules by a fully printable industrial-scale process, delivering 11.2% efficiency stable for >10,000 h with zero loss in performances measured under controlled standard conditions. This innovative stable and low-cost architecture will enable the timely commercialization of perovskite solar cells.

Up-scaling represents a key challenge for photovoltaics based on metal halide perovskites. Using a composite of 2D and 3D perovskites in combination with a printable carbon black/graphite counter electrode; Grancini et al., report 11.2% efficient modules stable over 10,000 hours.

Self-Organization in Nanoparticle Titanium Dioxide Thin Films

Nanocrystalline titanium dioxide has been synthesized using a sol-gel technique followed by hydrothermal growth at temperatures in the range 190-270°C. Thin films of these colloids were studied using x-ray diffraction (XRD), scanning electron microscopy (SEM), and nitrogen adsorption/desorption. Self-organization of the nanocrystalline particles in regular arrays was observed in films made from colloids autoclaved at lower temperatures. We present herein initial photovoltaic performance of these semiconducting films used as working electrodes in a dye-sensitized solar cell.

Hierarchical TiO2 photoanode for dye-sensitized solar cells

Hierarchical or one-dimensional architectures are among the most exciting developments in material science these recent years. We present a nanostructured TiO(2) assembly combining these two concepts and resembling a forest composed of individual, high aspect-ratio, treelike nanostructures. We propose to use these structures for the photoanode in dye-sensitized solar cells, and we achieved 4.9% conversion efficiency in combination with C101 dye. We demonstrate this morphology beneficial to hamper the electron recombination and also mass transport control in the mesopores when solvent-free ionic liquid electrolyte is used.

Highly phosphorescence iridium complexes and their application in organic light-emitting devices

A new series of iridium(III) mixed ligand complexes TBA[Ir(ppy)(2)(CN)(2)] (1), TBA[Ir(ppy)(2)(NCS)(2)] (2), TBA[Ir(ppy)(2)(NCO)(2)] (3), and [Ir(ppy)(2)(acac)] (4) (ppy = 2-phenylpyridine; acac = acetoylacetonate, TBA = tetrabutylammonium cation) have been developed and fully characterized by UV-vis, emission, IR, NMR, and cyclic voltammetric studies. The lowest energy MLCT transitions are tuned from 463 to 494 nm by tuning the energy of the HOMO levels. These complexes show emission maxima in the blue, green, and yellow region of the visible spectrum and exhibit unprecedented phosphorescence quantum yields, 97 +/- 3% with an excited-state lifetimes of 1-3 micros in dichloromethane solution at 298 K. The near-unity quantum yields of these complexes are related to an increased energy gap between the triplet emitting state and the deactivating e(g) level that have been achieved by meticulous selection of ligands having strong ligand field strength. Organic light-emitting devices were fabricated using the complex 4 doped into a purified 4,4'-bis(carbazol-9-yl)biphenyl host exhibiting a maximum of the external quantum efficiencies of 13.2% and a power efficiency of 37 lm/W for the 9 mol % doped system.

Evaluation of genotoxic and immunotoxic activities of potential glucose biosensor components: ferrocenes

Three ferrocenes used in glucose biosensor construction were tested in the aspect of genotoxic and immunotoxic activities. All three ferrocenes were not mutagenic in the standard bacterial Ames test. Equally in the Sister Chromatid Exchanges test in human lymphocyte cultures, the genotoxic action of tested ferrocenes could be excluded. However, all three significantly decreased the rate of lymphocyte proliferation and especially diminished the numbers of B-lymphocytes and NK-cells after 72 hours of in vitro culture. Marked differences between the ferrocenes in their immunotoxic activities were noticed, and we were able to select those which would be relatively safe and those which should be avoided in further investigation of the glucose biosensor construction. Our results indicate the necessity to estimate immunotoxic effects as well as genotoxic effects, especially in biosensor components potentially used in vivo.