The central role of ligands in electron transfer from perovskite nanocrystals

The nanoscale miniaturization of hybrid organic-inorganic perovskite has given rise to new functionalities, but the full understanding of the multifaceted properties of perovskite nanostructures is still incomplete. Using a combination of optical and magnetic resonance (EPR) spectroscopies, we focused our investigation on the photoinduced electron transfer process taking place in perovskite nanocrystals blended with the fullerene derivative PCBM. In particular we analyzed the different effect of two types of nanocrystal ligands, namely octylamine and oleylamine, on the photoinduced processes. The electron transfer process resulted in efficient fluorescence quenching in a mixed solution and in the formation of charges (PCBM anions) detected by EPR in the blends. Both the optical and EPR techniques revealed a stronger effect when the shorter ligand is present. Finally, pulsed EPR demonstrated the stabilization of the photogenerated charges in proximity of perovskite nanocrystals.