Development of New Electron Transport Layer Materials for Perovskite Solar Cells

Abstract

There has been a significant progress in the development of perovskite solar cells (PSCs) over the past decade, and currently the performance of these solar cells is comparable and even better than commercial silicon based solar cells. However, there is still much progress to be made. The work described in this report contributes to enhancing the performance of PSCs by developing new electron transport layer (ETL) materials. In particular, we present two projects aimed at developing new ETL materials that could improve the performance of PSCs. The first project consists in the synthesis of materials based on the naphthalene diimide (NDI) structure. We synthesized three NDI dimers that have substituents at the imide position and that almost do not absorb light in the visible region. We also synthesized a bis-substituted α-naphthalene NDI that only absorbs slightly in the visible region. These four compounds can be sublimed under vacuum, although the alkyl NDI dimer decomposes at the temperature needed to sublimate it. Two of these four compounds have been sent to other research groups to evaluate their performance as ETL materials in PSCs. The second project consists in the development of new ETL materials by modifying fullerene compounds with the objective to improve their mechanical properties. In the first part of this project we crosslinked C60 and PCBM with diazirine compounds and fabricated devices to then evaluate their performance. The J-V curves obtained brought us to the conclusion that these crosslinked fullerene compounds show good electrical device performance. In the second part of this project we determined different temperatures and periods of time at which the crosslinking between C60 and a polymer occurred.