Abstract This work aimed to produce CH3NH3PbI3 and CH3NH3PbBr3 films on glass substrates via the automated spray-pyrolysis technique for application as an absorber layer of photovoltaic cells. Their properties were investigated and compared by varying deposition parameters, such as the temperature (250, 300, 350, and 400 °C) and the precursor solution flow (0.25, 0.50, and 0.75 mL/min). Structural characterization by X-ray diffraction revealed the formation of orthorhombic perovskite films. The most adequate temperature and solution flow were 300 °C and 0.50 mL/min for both bromine and iodide films. Morphologically, the films were uniform and free from cracks. CH3NH3PbI3 and CH3NH3PbBr3 films respectively had an optical gap of 1.5 and 2.3 eV, a thickness of 4.56 and 2.35 µm, an absorption coefficient of 0.58x104 and 0.50x104 cm-1, a resistivity of 21.80 and 24.20 kΩ.m, and a figure of merit of 2.66 and 2.07. It was concluded that, between the two compounds, the CH3NH3PbI3 layer has better performance for photovoltaic applications.

Resumo O efeito da dopagem com cobre nas propriedades estruturais, elétricas e óticas de filmes de óxido de zinco foi avaliado. Filmes dopados com cobre (ZnO:Cu) foram depositados com sucesso em um substrato de vidro por spray-pirólise com concentração de dopante de 0, 2,5 e 7,5 %at (ZnO, ZC2.5, ZC7.5). Todos os filmes foram policristalinos, com fase wurtzita hexagonal do ZnO. Os filmes apresentaram cristalitos nanoestruturados de 36,7 a 38,2 nm. A dopagem de cobre aumentou a condutividade elétrica dos filmes de ZnO; essa mudança foi proporcional ao teor de dopante. Os filmes apresentaram elevada transmitância ótica de 70-80% na região do espectro de luz visível. O gap ótico decresceu com a dopagem com Cu. Para todos os filmes o espectro de fotoluminescência apresentou emissão ultravioleta intensa e uma emissão azul mais fraca. As emissões se deslocaram para menores comprimentos de onda para maiores concentrações de dopante. ZC7.5 apresentou as propriedades mais promissoras para aplicações como óxido condutor transparente: transmitância ótica e fotoluminescência UV intensas, além da menor resistividade elétrica.

Abstract The effect of copper doping on structural, electrical, and optical properties of zinc oxide films was evaluated. Copper-doped films (ZnO:Cu) were successfully deposited on a glass substrate by spray pyrolysis at doping levels of 0, 2.5, and 7.5 at% (ZnO, ZC2.5, ZC7.5). All films were polycrystalline, single-phase with ZnO hexagonal wurtzite structure. The films presented nanostructured crystallites, from 36.7 to 38.2 nm. Cu doping increased the electrical conductivity of the ZnO films; this change was proportional to the Cu concentration. The films presented high optical transmittance of 70-80% in the visible wavelength. The energy gap decreased upon Cu doping. The photoluminescence spectrum of all films displayed an intense ultraviolet emission and a weaker blue emission. The emissions shifted to lower wavelengths with increasing dopant concentrations. ZC7.5 presented the most promising properties for an application as transparent conducting oxide: intense optical transmittance and UV photoluminescence, also the lowest electrical resistivity.