ISBN 978-3-8439-5099-2

978-3-8439-5099-2, Reihe Anorganische Chemie

Feray Ünlü
Green Inks and Lead-free Compositions in Perovskite and Allied Materials for Photovoltaic Applications

270 Seiten, Dissertation Universität Köln (2022), Softcover, A5

Zusammenfassung / Abstract

Perovskites are currently recognized globally as highly efficient and multifunctional materials for a large variety of applications. Among emerging photovoltaic technologies, perovskite solar cells outperformed their counterparts due to the continuous evolution of their power conversion efficiency beyond 25%. Their high defect tolerance and compositional flexibility allow solution processing and tunability of optoelectronic properties, stability, efficiency, and even chemical safety through the facile change of both cations and anions. There are a plethora of device fabrication protocols and thus deviations are evident in the reported properties and performance metrics which pose questions regarding the mechanisms behind the liquid-to-solid transition and especially the solution dynamics in the perovskite precursor inks. To address this, spectroscopic methods were used to investigate the nature of perovskite precursor inks. In addition, the influence of solution composition parameters such as concentration, precursor ratio, solvents, A-site, and X-site ions and additives are studied. The dynamic solution equilibria are influenced by the choice of solvents, additives, and overall composition with structures in dimethyl sulfoxide and dimethyl formamide resembling solid-state ones. The main goal was to minimize the toxicity and safety risks of perovskite precursor inks and solar cells. Therefore, two holistic approaches were developed to eliminate the necessity of toxic solvents by using the protic ionic liquid methylammonium propionate in combination with water and alcohol. Secondly, lead was replaced by less toxic bismuth to design new perovskite-inspired materials, which are thoroughly studied towards optoelectronic properties, solar cell performance and stability to learn new strategies of optimizing and designing greener absorber materials.