Single crystals of heterovalent Bi-doped CH3NH3PbCl3 perovskite have been successfully grown through the inverse temperature crystallization method. Bandgap narrowing of 300 meV (a 55 nm red-shifting absorption edge) is obtained for the nominal 20% Bi-doped crystal with the host structure and the energy at the top of the valence band invariable. It is observed that the contact between the Au electrodes and single crystals transforms from Ohmic to Schottky, and the conductivity increases with increasing Bi doping level. By contrast, the Bi-doped CH3NH3PbCl3 thin films are also prepared, and the similar bandgap narrowing is found, although the narrowing degree is less than that in single crystals. This work has a comprehensive understanding of Bi-doped single crystals and thin films, providing further optoelectronic applications for these promising solution-processed hybrid perovskite semiconductor materials.

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In this paper, [(La0.9Sr0.1MnO3)n/(Pa0.9Ca0.1MnO3)n/(La0.9Sb0.1MnO3)n]m superlattices films have been deposited on (001) Nb:SrTiO3 substrates by a laser molecular-beam epitaxy technology. Expected ferroelectricity arise at well-defined tricolor superlattice at low temperature, composed of transition metal manganite, which is absent in the single-phase compounds. Furthermore, the ferroelectric properties of the superlattices are enhanced by increasing the periodicity m, which may be attributed to the accumulation of the polarization induced by the frustration. As for the magnetic hysteresis loop characteristics of the multilayer structures, the saturation magnetization and magnetic coercivity of films present definitely a strong periodic dependence. It also indicates that the frustration may exist in the tricolor superlattice. Our results further verify the previous theoretical research of generating multiferroics experimentally paving a way for designing or developing the novel magnetoelectric devices based on manganite ferromagnets.

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