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The intermediate-dimensional hybrid mixed-organic perovskite active layers PEA2(CH3NH3)n−1(PbI2)n and Dodec2(CH3NH3)n−1(PbI2)n with various n values were successfully fabricated. Their characteristics were compared to find out a promising candidate for solar cell applications. The appropriate layer thickness of the films was tuned by a variation of n values based on stoichiometry. The physical appearance, crystal structure, surface morphology, chemical bonding, optical properties, stability to the heat and humidity, and power conversion efficiency of all films were examined thoroughly to determine their potential. For low n values of both film types, they showed the quasi-2D characteristic improving the film stability and conversion efficiency. The absorption edge of both types of materials shifted to a higher energy side and the electronic band gap increased with the decrease of n values. The mixed phase and MAPbI3 perovskite diffraction peaks were still observable even after time has passed for 72 h. Under the 60% humidity condition, the PEA-doped MAPbI3 films decomposed slower than the Dodec-doped MAPbI3 films. [ABSTRACT FROM AUTHOR]

The p-type Ca3Co4O9 (CCO) and n-type CaMnO3 (CMO) thermoelectric oxide were synthesized stoichiometrically by the solid-state reaction technique. Both systems were investigated comparatively in aspects of thermoelectric and electrical properties. The material appearance, crystal structure, density, hardness, thermoelectric properties including Seebeck coefficient, electrical resistivity, and thermal conductivity, and electrical properties including dielectric constant, dielectric loss, and complex impedance of both systems were observed. Moreover, the P-E hysteresis loop of ferroelectric property and electrostriction were also investigated. The difference in the crystal structure, phase formation, and crystal growth conducts to the difference in physical, thermoelectric, and electrical properties. CMO was a cubic-perovskite type structure oxide with a higher density, less porosity, and smaller grain size with more thorough distribution as compared to orthorhombic structure CCO. Thus CMO could perform better values in terms of Seebeck coefficient, electrical resistivity, and thermal conductivity. In contrast, CCO possessed a larger grain size with an orthorhombic structure which has more favorable directions for dipole displacement. Hence, CCO exhibited a higher dielectric constant with lower dielectric loss. The complex impedance of both systems was in accordance with the RLC series circuit principle. Unfortunately, the P-E and S-E hysteresis loops of both systems could not be verified due to their electrical conductivity. [ABSTRACT FROM AUTHOR]