Degradation of metal-organic halide perovskites when exposed to ambient conditions is a crucial issue that needs to be addressed for commercial viability of perovskite solar cells (PSCs). Here, a concept of encapsulating CH3NH3PbI3 perovskite crystals with a multi-functional graphene-polyaniline (PANI) composite coating to protect the perovskite against degradation from moisture, oxygen and UV light is presented. Hole-conducting polymers containing 2D layered sheet materials are presented here as multi-functional materials with oxygen and moisture impermeability. Specific studies involving PANI and graphene composites as coatings for perovskite crystals exhibited resistance to moisture and oxygen under continued exposure to UV and visible light. Most importantly, no perovskite degradation was observed even after 96 h of exposure of the PSCs to extremely high humidity (99% relative humidity). Our observations and results on perovskite protection with graphene/conducting polymer composites open up opportunities for glove-box-free and atmospheric processing of PSCs.

Due to their outstanding optoelectronic properties, lead-based halide perovskite materials have been applied as efficient photoactive materials in solution-processed solar cells. Current record efficiencies offer the promise to surpass those of silicon solar cells. However, uncertainty about the potential toxicity of lead-based halide perovskite materials and their facile dissolution in water requires a search for new alternative perovskite-like materials. Thanks to the foresight of scientists and their experience in lead-based halide perovskite preparation, remarkable results have been obtained in a short period of time using lead-free perovskite compositions. However, the lower solar-to-energy conversion efficiency and long-term stability issues are serious drawbacks that hinder the potential progression of these materials. Here, we review and analyse strategies in the literature and the most promising solutions to identify the factors that limit the power conversion efficiency and long-term stability of lead-free tin-based perovskite solar cells. In the light of the current state-of-the-art, we offer perspectives for further developing these promising materials.

is a promising material for heat flux sensors based on the anomalous Nernst effect (ANE) because of its sizable uniaxial magnetic anisotropy (Ku) and low saturation magnetization (Ms). We experimentally and theoretically investigated the ANE and anomalous Hall effect in sputter-deposited Mn4N films. It was revealed that the observed negative anomalous Hall conductivity (xy) could be explained by two different coexisting magnetic structures, that is, a dominant magnetic structure with high Ku contaminated by another structure with negligible Ku owing to an imperfect degree of order of nitrogen. The observed transverse thermoelectric power (SANE) of +0.5 V/K at 300 K gave a transverse thermoelectric

In recent years, perovskite halide compounds have attracted attention for the fabrication of highly efficient solar cells, light-emitting diodes, and X-ray detection. However, a comprehensive understanding of their microscopic origins has not been fully explored. In this work, the effect of Mn doping in organic–inorganic perovskite semiconductor methylammonium lead iodide (CH3NH3PbI3) has been studied. The existence of magnetism in CH3NH3PbI3 (MAPbI3) has been confirmed by magnetization measurements at room temperature. A drastic enhancement in magnetic moment is obtained in Mn (15%)-doped MAPbI3. The influence of Mn doping in MAPbI3 films has been analyzed for structural and morphological changes. Room-temperature ferromagnetism is achieved by the incorporation of Mn2+/Mn3+ ions into Mn (3–20%)-doped MAPbI3 films by the effect of eminent double-exchange and superexchange interactions in between the Mn2+–I – –Mn3+ ions compared with other doping content. Our finding offers an alternative pathway for spintronic, light-controlled magnetic and photovoltaic devices.

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