PROBIEN   20416
INSTITUTO DE INVESTIGACION Y DESARROLLO EN INGENIERIA DE PROCESOS, BIOTECNOLOGIA Y ENERGIAS ALTERNATIVAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Low pressure vapor phase deposition as a method to obtain lead iodide precursor for two step perovskite films with control on film growth
Autor/es:
FLAVIO SOLDERA; M. DOLORES PEREZ; ALEJANDRO KOFFMAN FRISCHKNECHT; MARCOS SOLDERA; MAURICIO TROVIANO; LUCIANO CARLOS; KURT TARETTO
Lugar:
Oxford
Reunión:
Conferencia; 3rd Inter International Conference on Perovskite Solar Cells and Optoelectronics; 2017
Institución organizadora:
University of Oxford, UK
Resumen:
Lead iodide is a wide-gap semiconductor with interesting electro-optical properties that has been receiving a great deal of attention due to its application in the synthesis of perovskite solar cells. Perovskites films have been prepared by a number of different deposition techniques, mostly from the precursors in solution, with some effort dedicated to the evaporation processes [1]. In particular, low pressure vapor phase deposition (LP-VPD) arises as a promising technique that allows high control of the films morphology by fine tuning the different deposition variables while reducing the material waste [2,3]. The LP-VPD method relies on the sublimation of a substance under low vacuum by an inert carrier gas transport, from the hot region towards the cold zone. In this work we implement an experimental setup which comprises a four-temperature zones gradient that allows precise control of the LP-VPD deposited films. We present a preliminary study of the preparation of lead iodide films by the LP-VPD method as means to further study the perovskite formation and the impact of PbI2 morphology into the synthesis of large perovskite crystals. The ability of fine tuning the films´ structural properties is evaluated by modification of the substrate material, deposition time, and evaporation temperature. The films were characterized by electronic microscopy (SEM), x-ray diffraction (XRD), global reflectance (R) and transmittance (T) in the visible spectrum and room temperature photoluminescence (PL) spectrometry.Well defined hexagonal crystals, or platelets with hcp crystal structure were obtained for all samples. Such structures have been reported earlier for VPD under cared conditions [4]. Films grown on glass at high substrate temperatures (80ºC) and low evaporation temperatures (310ºC) show highly oriented platelets with a preferential (001) orientation parallel to the substrate. Lower substrate temperatures (40ºC) yielded non-parallel platelets, which produced voids within the films. PL spectra show signal variations with temperature and time tuning that can be related to structural changes. From RT measurements the absorption coefficient, the Urbach energy and the band gap were obtained and compared to literature values. References[1] Yang, S. et. al., J. Mater. Chem. A (2017), 5, 11462[2] Burrows, P. E. et al., J. Cryst. Growth (1995), 156, 91-98.[3] Forrest, S., Nature (2004), 428, 911-918.[4] Schieber, M. et al., J. Cryst. Growth (2008), 310, 3168-3173.