N-type buffer-free interface for efficient low-light organic photosensitive electronics

The analysis of the affinity between the interfaces in organic photovoltaic devices is crucial for elucidating their operating mechanisms. N,N′-bis{3-[3-(dimethylamino)propylamino]propyl}perylene-3,4,9,10-tetracarboxylic diimide (PDINN), an aliphatic amine-functionalized perylene diimide, is predominantly employed as an electron-transport layer (ETL) that aids in the extraction of electrical charges from organic photodetectors. However, its usage is primarily limited to non-fullerene acceptor-based active layers. In this study, atomic force microscopy (AFM) imaging and whole and line profiles are utilized to precisely assess the affinity between PDINN and fullerene acceptors. The analysis of the photovoltaic and photodetector characteristics at different light intensities, voltages, and wavelengths reveals that the PDINN-free devices exhibit exceptional performance. Specifically, the PDINN-free devices display a high responsivity and a remarkable detectivity of ∼1014 Jones under low-light conditions of 700 lux or below.