Non-Fullerene Organic Electron-Transporting Materials for Perovskite Solar Cells

Organic electron-transporting materials (ETMs) with low-temperature solution processability and high electron-transfer/transport characteristics have received significant attention for their use in high-performance perovskite solar cells (PSCs). In contrast to widely investigated fullerene-based organic ETMs for PSCs, only a few types of non-fullerene-based ETMs have been developed. In this Concept article, a representative design concept for non-fullerene ETMs is described for use in normal (n-i-p) and inverted (p-i-n) type PSCs. On the basis of a discussion on ETM requirements for PSCs, recently developed non-fullerene polymeric and small-molecule-based ETMs for PSCs are highlighted, alongside various other approaches for enhancing PSC device performance, such as using additional dopants and introducing amine terminal groups in the ETMs and ETM-based interlayers. This Concept provides a basic design concept for non-fullerene-based ETMs in PSCs.