Evaluation of Mulliken Electronegativity on CH3NH3PbI3 Hybrid Perovskite as a Thought-Provoking Activity

Abstract

We implement an activity with graduate students to reinforce basic concepts of chemistry such as electron affinity, electronegativity, and ionization energy in order to improve their skills in designing and fabricating solar cells. At the same time, we use the Mulliken electronegativity method to evaluate energy levels of materials commonly applied in hybrid perovskite solar cells. Although this method does not always result in energy values comparable to those obtained experimentally or that are reported in literature, we consider that the limitations of this method can be an effective approach to generating thought in class and expanding the knowledge of students about the electronic properties, crystalline structure, and orbital states of some materials, such as CH3NH3PbI3. The analysis of a complementary activity and evaluation form shows that at least 75% of the students who worked on this activity improved their understanding of basic chemistry, the CH3NH3PbI3 molecule, and the design of solar cells. At the same time, they found this activity challenging enough to generate thought and make them consider new concepts. Also, the design of this activity allowed them to correctly evaluate the energy levels of CH3NH3PbI3 using the Mulliken method for the first time. This evaluation is possible only after considering the structural and electronic properties of CH3NH3PbI3. These results agree with experimental values reported in the literature.