Although the theoretical capacitance of MnO is 1370 F g based on the Mn/Mn redox couple, most of the reported capacitances in literature are far below the theoretical value even when the material goes to nanoscale. To understand this discrepancy, in this work, the electrochemical behavior and charge storage mechanism of K-inserted α-MnO (or KMnO) nanorod arrays in broad potential windows are investigated. It is found that electrochemical behavior of KMnO is highly dependent on the potential window. During cyclic voltammetry cycling in a broad potential window, K ions can be replaced by Na ions, which determines the pseudocapacitance of the electrode. The K or Na ions cannot be fully extracted when the upper cutoff potential is less than 1 V vs Ag/AgCl, which retards the release of full capacitance. As the cyclic voltammetry potential window is extended to 0-1.2 V, enhanced specific capacitance can be obtained with the emerging of new redox peaks. In contrast, the K-free α-MnO nanorod arrays show no redox peaks in the same potential window together with much lower specific capacitance. This work provides new insights on understanding the charge storage mechanism of MnO and new strategy to further improve the specific capacitance of MnO-based electrodes.

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.

important problem is related to the high acute and chronic toxicity of the lead compounds, which can cause occupational health risks and hinder massive industrial production of raw materials and photovoltaic modules. [3] The need for recycling of the lead-containing photovoltaic panels at the end of their life cycle represents another issue, which has been experienced already in the case of CdTe technology. [4] Thus, the facile photo degradation of complex iodoplumbates and their anticipated negative impact on the environment provide impetus for the development of alternative lead-free light absorbers based on metal halides. [5] Complex tin (II) and germanium (II) halides with the perovskite crystal lattice were thoroughly investigated in effort to develop a new generation of light harvesting materials for solar cells. However, ASnX 3 and AGeX 3 systems (A represents organic cation and X = I, Br) delivered inferior photovoltaic efficiencies, while demonstrating even lower intrinsic stability than the iodoplumbates due to easy disproportionation of M (II) into M (0) and M (IV). [6] Therefore, the most recent efforts have been focused on the exploration of halide complexes of the posttransition group 15 elements such as Bi and Sb. Along with the pioneering reports on BiI 3[7] and A 3 Bi 2 I 9 (A = MA or Cs), [8] a number of other bismuth halides were considered such as BiSI, BiOI, AgBi 2 I 7 , and Cs 2 AgBiX 6 (X = Br, Cl). [9] The range of antimony (III) halides investigated in photovoltaic cells is limited to A 3 Sb 2 I 9 (A = MA, Rb, Cs). [10] Unfortunately, all binary and complex Bi(III) and Sb(III) halides so far tested delivered rather modest photovoltaic performances ranging from 0.1% to 1.2%. Low external quantum efficiencies (EQEs <20-30%) strongly suggest inefficient generation of charge carriers in the photo active layer and/or their hindered transport to the respective electrodes.Here, we report the first perovskite-like antimony (V) complex halide with the pseudo-3D crystal structure, which demonstrates EQE of ≈80% and decent power conversion efficiencies close to 4% in planar junction solar cells.While the photovoltaic properties of Sb(III) iodides have been intensively investigated within the last couple of years, halide complexes of Sb(V) remain unexplored. Yet, bromoantimonates (V) or so-called mixed valence complexes containing both Sb(III) and Sb(V) species were first reported more than 70 years ago. [11] These compounds represent intensively colored

We review the concepts of quantum entanglement and quantum discord and present the entropic measures for these information correlations. We further provide examples demonstrating the presence of quantum information correlations in different paramagnetic materials with ferro- and antiferromagnetic coupling. The temperature behavior of the discord for atomic nuclear spins and decoherence of quantum states with electron and nuclear spins is discussed.

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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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Herein, we reveal for the first time a comprehensive mechanism of poorly investigated electrochemical decomposition of CH3NH3PbI3 using a set of microscopy techniques (optical, AFM, PL) and ToF-SIMS. We demonstrate that applied electric bias induces the oxidation of I– to I2, which remains trapped in the film in the form of polyiodides, and hence, the process can be conceivably reversed by reduction. On the contrary, reduction of organic methylammonium cation produces volatile products, which leave the film and thus make the degradation irreversible. Our results lead to a paradigm change when considering design principles for improving the stability of complex lead halide materials as those featuring organic cations rather than halide anions as the most electric field-sensitive components. Suppressing the electrochemical degradation of complex lead halides represents a crucial challenge, which should be addressed in order to bring the operational stability of perovskite photovoltaics to commercially interesting benchmarks.