We report here all inorganic CsPbI planar junction perovskite solar cells fabricated by thermal coevaporation of CsI and PbI precursors. The best devices delivered power conversion efficiency (PCE) of 9.3 to 10.5%, thus coming close to the reference MAPbI-based devices (PCE ≈ 12%). These results emphasize that all inorganic lead halide perovskites can successfully compete in terms of photovoltaic performance with the most widely used hybrid materials such as MAPbI.

We report a careful and systematic study of thermal and photochemical degradation of a series of complex haloplumbates APbX (X = I, Br) with hybrid organic (A = CHNH) and inorganic (A = Cs) cations under anoxic conditions (i.e., without exposure to oxygen and moisture by testing in an inert glovebox environment). We show that the most common hybrid materials (e.g., MAPbI) are intrinsically unstable with respect to the heat- and light-induced stress and, therefore, can hardly sustain the real solar cell operation conditions. On the contrary, the cesium-based all-inorganic complex lead halides revealed far superior stability and, therefore, provide an impetus for creation of highly efficient and stable perovskite solar cells that can potentially achieve pragmatic operational benchmarks.

Electromechanical response of materials is a key property for various applications ranging from actuators to sophisticated nanoelectromechanical systems. Here electromechanical properties of the single-layer graphene transferred onto SiO2 calibration grating substrates is studied via piezoresponse force microscopy and confocal Raman spectroscopy. The correlation of mechanical strains in graphene layer with the substrate morphology is established via Raman mapping. Apparent vertical piezoresponse from the single-layer graphene supported by underlying SiO2 structure is observed by piezoresponse force microscopy. The calculated vertical piezocoefficient is about 1.4 nm V−1, that is, much higher than that of the conventional piezoelectric materials such as lead zirconate titanate and comparable to that of relaxor single crystals. The observed piezoresponse and achieved strain in graphene are associated with the chemical interaction of graphene's carbon atoms with the oxygen from underlying SiO2. The results provide a basis for future applications of graphene layers for sensing, actuating and energy harvesting.

We report the first systematic assessment of intrinsic photothermal stability of a large panel of complex lead halides APbX3 incorporating different univalent cations (A = CH3NH3 +, [NH2CHNH2]+, Cs+) and halogen anions (X = Br, I) using a series of analytical techniques such as UV–vis and X-ray photoelectron spectroscopy, X-ray diffraction, EDX analysis, atomic force and scanning electron microscopy, ESR spectroscopy, and mass spectrometry. We show that heat stress and light soaking induce a severe degradation of perovskite films even in the absence of oxygen and moisture. The stability of complex lead halides increases in the order MAPbBr3 < MAPbI3 < FAPbI3 < FAPbBr3 < CsPbI3 < CsPbBr3, thus featuring all-inorganic perovskites as the most promising absorbers for stable perovskite solar cells. An important correlation was found between the stability of the complex lead halides and the volatility of univalent cation halides incorporated in their structure. The established relationship provides useful guidelines for designing new complex metal halides with immensely improved stability.

Li-ion battery performance and life cycle strongly depend on a passivation layer called solid-electrolyte interphase (SEI). Its structure and composition are studied in great details, while its formation process remains elusive due to difficulty of in situ measurements of battery electrodes. Here we provide a facile methodology for in situ atomic force microscopy (AFM) measurements of SEI formation on cross-sectioned composite battery electrodes allowing for direct observations of SEI formation on various types of carbonaceous negative electrode materials for Li-ion batteries. Using this approach, we observed SEI nucleation and growth on highly oriented pyrolytic graphite (HOPG), MesoCarbon MicroBeads (MCMB) graphite, and non-graphitizable amorphous carbon (hard carbon). Besides the details of the formation mechanism, the electrical and mechanical properties of the SEI layers were assessed. The comparative observations revealed that the electrode potentials for SEI formation differ depending on the nature of the electrode material, whereas the adhesion of SEI to the electrode surface clearly correlates with the surface roughness of the electrode. Finally, the same approach applied to a positive LiNi1/3Mn1/3Co1/3O2 electrode did not reveal any signature of cathodic SEI thus demonstrating fundamental differences in the stabilization mechanisms of the negative and positive electrodes in Li-ion batteries.

most successful to date were complex lead halides comprising simultaneously several univalent cations (Cs + , CH 3 NH 3 + or MA + , [H 2 NCHNH 2 ] + or FA +) and halide anions (typically Br − , I −) in their crystal lattice. [2] However, these materials suffer from low photostability. In particular, Hoke et al. first demonstrated that the mixed-halide MAPb(I 1−x Br x) 3 absorbers undergo rapid light-induced halide segregation with the formation of I-rich and Br-rich phases leading to both structural and energetic disorder resulting in a significant decrease in solar cell performance. [3,4] While the effect of short light exposure was found to be essentially reversible in the dark, long-term irradiation of the mixed halide perovskite films results in their complete degradation. [5] Therefore, light-induced halide phase segregation is considered as a severe limitation for achieving long-term operational stability of perovskite solar cells based on the absorbers incorporating more than a single halide anion. [6] Overcoming this problem is crucially important for the development of tandem devices with the upper cell based on the perovskite absorber with the tailored optical properties realized through halide mixing. Since the discovery of the light-induced halide phase segregation in complex lead halides, many research groups have investigated this phenomenon in detail in an attempt to reveal its mechanism. Multiple models varying in the origin

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Here we explore the effect of the partial substitution of univalent methylammonium cations (MA) with hydrazinium ions (HA) on the stability, morphology and photovoltaic performance of hybrid MA(1−x)HAxSnI3 systems.