High-performance circularly polarized photodetectors based on chiral transfer of achiral poly(9,9-dioctylfluorene)†

Abstract

Circularly polarized light (CPL) detection adds a unique dimension to optical information processing and communication, holding great promise for applications in fields such as bioimaging and optical communications. However, the scarcity of suitable active photovoltaic materials for CPL detection has impeded progress in CPL detector development. In this study, a CPL sensing layer was created by annealing-induced chiral transfer of a chiral small molecule (4-[[4-(hexyloxy)benzoyl]oxy]-1,1′-[1,1′-binaphthyl]-2,2′-diester) benzoic acid (S6N) with poly(9,9-dioctylfluorene) (PFO). By designing bilayer-structured devices with a high-performance donor–acceptor conjugated polymer as the charge-transfer layer, organic field-effect transistor detectors capable of CPL differentiation were fabricated, which further solved the problem of poor electrical performance due to the distorted structure of CPL sensing materials. This approach is simple and effective. The resulting high-performance CPL detector demonstrated a strong discriminatory ability for CPL at 405 nm, with a significant photocurrent asymmetry factor (g_ph) of 0.58. The detector effectively encoded and transmitted the message “GD” utilizing the Morse code. Moreover, a 3 × 3 device array was assembled to simulate image encryption using the letters “HFUT”. This strategy of blending-induced chiral transfer in combination with bilayer device design provides a direct and efficient route to the development of advanced CPL detectors, which is important for the development of spintronics, cryptography and quantum optics.