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Hybrid solar cells based on perovskite

Author(s):
Rodrigo Szostak
Total Authors: 1
Document type: Master's Dissertation
Institution: Universidade Estadual de Campinas. Instituto de Química
Defense date:
Examining board members:
Roberto Mendonça Faria; Italo Odone Mazali
Advisor: Ana Flávia Nogueira
Abstract

Perovskite-based solar cells efficiency have reached 20 % in less than a decade of research, becoming commercially attractive due to their low-costs and simple preparation methods. However, many factors that influence perovskite formation and properties are yet to be better understood, and controlling these factors is fundamental to its continuing improvement and stability. Thus, MAPbI3 perovskite formation by intramolecular exchange method was studied as the first part of this work. It was demonstrated that the perovskite formation by this method happened through the formation one intermediate, MA2Pb3I8.2DMSO, when the sample was not exposed to atmosphere during the preparation, which is converted to perovskite by annealing process. Nonetheless, when atmosphere contact occurs, perovskite formation undergoes straightforward. In this way, it was possible to propose a mechanism of formation with the participation of ambient H2O. In the second part, a study of the effect of annealing time of the perovskite films was performed. With short annealing time, the excess of methylammonium iodide is not completely eliminated, leading to the formation of defects that decreases the efficiency of the solar cells. With increasing annealing time, this effect is minimized and evidenced by reduction of the hysteresis and improvement efficiency of solar cells. With 90 minutes of annealing time, it was possible prepare solar cells with average efficiency of 11,00 % in inverse, and 10,25 % in forward measurement. After stabilization, the efficiency reached 12,89 %. Thereby, it was possible to demonstrate that the ambient H2O and annealing time are factors that influence decisively in the perovskite formation without secondary PbI2 phase and, consequently, in obtaining solar cells with good efficiency. (AU)

FAPESP's process: 14/13666-0 - Hybrid solar cells based on perovskite
Grantee:Rodrigo Szostak
Support type: Scholarships in Brazil - Master