Nonfullerene Self-Assembled Monolayers As Electron-Selective Contacts for <i>n-i-p</i> Perovskite Solar Cells
Drajad Satrio Utomo, Lauryna Monika Svirskaite, Adi Prasetio, Vida Malinauskienė, Pia Dally, Erkan Aydın, Artem Musiienko, Vytautas Getautis, Tadas Malinauskas, Randi Azmi, Stefaan De Wolf
Abstract
High Resolution Image Download MS PowerPoint Slide Organic, nonfullerene semiconductors capable of self-assembly and composed of either anthraquinone (AQ) or naphthalenediimide (NDI) central fragments have been designed as electron-selective materials for n-i-p perovskite solar cells (PSCs). Both types of self-assembled monolayer (SAM) molecules contain phosphonic acid as an anchoring group, allowing covalent binding with indium tin oxide (ITO) surfaces. In particular, the NDI-based SAMs showed a more homogeneous anchoring on the ITO substrate and a stronger band bending at the ITO-SAM/perovskite interface than AQ-based SAMs. As a result, low-temperature-processed n-i-p PSCs with NDI SAMs as an electron-selective bottom contact showed a maximum power conversion efficiency (PCE) of 21.5%, representing the highest PCE among n-i-p PSCs with organic electron transporting layers (ETLs). In addition, our NDI-SAM-based devices demonstrate substantially improved long-term stability under operating temperature conditions when compared to devices using SnO 2 as the ETL.