Naphthalene Diimide-Based Molecules for Efficient and Stable Perovskite Solar Cells

Naphthalene-diimide (NDI)-based molecules have shown an interesting behaviour within the field of perovskite solar cells, thanks to their promising application as electron transporting materials. In this paper, three novel NDI-containing molecules are synthesized and fully characterized, more specifically two polymers and an analogue small molecule. Each one of the NDI units contains an amine, either tertiary or quaternary, which is a moiety known for improving the conductivity. The newly synthesized compounds are suitable for the use as n-type buffer layers on the top of PC₆₁BM, thanks to their appropriate energy levels and their solubility in polar solvents. The photovoltaic performances of the NDI-containing cells are highly comparable to those of the reference cells, which contain bathocuproine (BCP) as buffer layer. Furthermore, the stability of the NDI-containing cells is higher than that of the BCP reference.