Hybrid solar cells based on perovskite

Abstract

The energy demand has been increasing substantially during the last years due to the growing population and big electricity dependency. The photovoltaic solar energy is a renewable source and promising to supply the global energy needs. Since 2009, perovskites of the type CH3NH3PbX3(X=Cl, Br ou I) have been used in solar cells due to their optimal performance, which is overcoming current efficiency records and reaching values close to 18%. The properties of this material are still poorly known. Nevertheless they are promising to the production of low cost devices with high efficiency. Thus, the present master's degree project has the objective of introducing studies about perovskites of the type CH3NH3PbX3 in solar cells at the Laboratório de Nanotecnologia e Energia Solar (LNES) at UNICAMP. Initially the deposition of the perovskite CH3NH3PbI3 over the TiO2 porous electrode will be optimized. The parameters concentration of lead iodide (PbI2), speed of the deposition of PbI2 by spin coating, concentration of methylammonium iodide (CH3NH3I) in isopropanol and time of the dipping will be varied, with objective of optimizing the deposition. Afterwards, porous TiO2 electrode will be prepared and covered with Al2O3, MgO, Nb2O5 or SrTiO3 oxides by the sol-gel method aiming to reduce recombination between the perovskite and the hole conductor spiro-OMeTAD (2,22,7,72-tetrakis(N,N2-di-p-methoxyphenylamine)-9,92-spirobifluorene) and thus promote an increase in the efficiency of the devices. The morphological and structural characteristics will be followed by the x-ray diffraction, atomic force microscopy, scanning electronic microscopy and energy-dispersive x-ray spectroscopy techniques. photovoltaic characterization and charge transfer will be followed by obtaining current and voltage curves in the dark and under light, quantum efficiency curves in function of wavelength, fluorescence emission spectroscopy, UV-Vis., spectroscopy, transient absorption spectroscopy and electrochemical impedance spectroscopy. (AU)