Synthesis route for cesium and thiocyanate doped halide perovskite thin films for a new generation of solar cells

Abstract

A novel, efficient, low-cost, and long-term lifetime photovoltaic technology is essential for accelerating the energy transition to renewable energy sources. Perovskite thin films stand out as promising photovoltaic technologies due to competitive power conversion efficiencies over 20% and low-cost fabrication techniques [1]. Nevertheless, this technology is still affected by short lifetimes that are consequence of the strong sensitivity of the pristine perovskites to effects such as moisture, UV radiation, and the presence of oxygen. Doping the perovskite materials to change their intrinsic properties and increase their stability is one of the proposed solutions to this issue [2]. In this work, we study the synthesis route to fabricate the double partial substitution with cesium and thiocyanate (SCN) in the methylammonium (MA) and iodide sites, respectively, of the pristine perovskite compound MAPbI3. Individually, these substitutions have shown to enhance the structural stability of the perovskites and increase their resistance to moisture and ambient conditions. However, to the best of our knowledge, the proposed double substitution has not been studied. The project’s first stage was manufacturing an acrylic glove box. This process included the design, cut of acrylic sheets, sanding, assembling, and tuning of the system. The second stage was preparing perovskite precursor solutions according to predefined stoichiometry amounts of thiocyanate, methylammonium, and cesium. In the third stage, perovskite thin films were deposited on a glass substrate, annealed on a hot plate, and characterized by means of scanning electron microscopy (SEM) x-ray diffraction (XRD) and IR-VIS absorption spectroscopy. The synthesis process uses the one-step spin-coating technique, chlorobenzene as an antisolvent, and a substrate preheating stage.