Improved performance and stability of hole-conductor-free mesoporous perovskite solar cell with new amino-acid iodide cations

Abstract

Carbon-based and hole-transporting-material-free perovskite solar cells (PSCs) are a promising alternative structure for low-cost applicable method to their manufacturing. However, in this technology, the presence of 5-ammonium valeric acid iodide (5-AVAI) as co-cation to the commonly used MAPbI3 perovskite is necessary which promotes the crystal nucleation and growth within TiO2/ZrO2 mesoscopic oxide scaffold, while affects the contact of perovskite with hydrophobic carbon electrodes. Herein, we present the use of alternative and very low-cost amino acids with comparable and even better performance in some cases of as-used 5-AVAI. On that purpose, two common amino acids of dl-leucine and dl-alanine are used for the synthesis of their iodide derivatives also performed as co-cation with methyl ammonium iodide into the MAPbI3. The structural, optical, and electrical characteristics of the PSCs prepared with newly presented amino acids are examined in comparison with those obtained for (5-AVA)xMA1–xPbI3 perovskite as a reference. In the case of dl-leucine iodide-based perovskite, enhanced stability and performance over 5-AVAI was monitored to their PSCs for over 120 days referring to unsealed devices under 60% relative humidity.