Properties of MAPbI3 perovskite layers grown with HCl additions
Résumé
Lead halide perovskites, used to produce photovoltaic devices, have been thesubject of a huge research effort these last years. This is due to the spectac-ular improvement of the conversion effciency results within a short amount oftime. However, some issues have been identified, which include stability, leaduse and cost of some precursors. It has recently been shown that low purity, lowcost PbI2 could be succesfully used in the synthesis of the MAPbI3 perovskite,provided that HCl is added during the synthesis to prevent solubility problems.Thus, it is of high interest to provide information pertaining to the materialquality, in relation with the HCl additions performed during synthesis. In thiswork, we have grown three sets of samples with different HCl to (PbI 2 + MAI)molar ratios (R HCl ), where PbI2 and methylamine iodide (MAI) are the precur-sors of the perovskite. We used RHCl = 0 (no HCl), 0.5 and 1.2 . We performedx-ray diffraction, transmittance and 77K photoluminescence experiments in or-der to assess the material structural and optoelectronic properties and foundthat an optimum HCl concentration must be used. HCl introduction clearlyhas a beneficial effect both on domain sizes and photoluminescence intensityat RHCl = 0.5, but lead to subsequent degradation of the perovskite quality athigher RHCl .