Coherent arrangement of perylene diimide derivative via adhesion-controlled transfer for noise-suppressed light signal detection

Abstract

In recent years, research in interfacial engineering has concentrated on enhancing the performance, stability, and reproducibility of organic optoelectronic devices. This study introduces a surface-controlled printing process for n-type perylene diimide (NPDI), a promising small molecule material utilized for efficient charge extraction in organic optoelectronic devices. The process aims to establish a coherent arrangement of the NPDI without aggregation. Surface control by the printing process induces uniform molecular interactions through a functionalized polymer substrate, effectively mitigating excessive self-aggregation inherent in the molecular structure of NPDI. In particular, we successfully achieve NPDI surface modification by selectively introducing the appropriate solvent, 2,2,2-trifluoroethanol, for the first time in the printing process. Organic optoelectronics with arranged NPDI exhibit a higher power conversion efficiency, with a noticeable improvement in the fill factor, which suppresses the dark current and contributes to enhancing the detectivity of the devices. In particular, the effective surface modification of NPDI suppresses recombination by reducing the trap density at the interface, as verified by the −3 dB cut-off frequency. Furthermore, this device, fabricated using eco-compatible solvents that are harmless to the human body, is confirmed to operate clearly with photoplethysmography (PPG) sensors based on its noise suppression.