Multilevel Chiral Semiconductor Metal-Peptide Framework Thin Film for Highly Circularly Polarized Visible Photodetection

The development of chiral metal-organic frameworks (MOFs) for highly circularly polarized (CP) photodetection in visible light is a challenging task. Herein, a wafer-scale multilevel chiral MOF thin film is prepared from helical secondary structural tripeptide ligand with a liquid-phase epitaxial layer-by-layer method for CP photodetector. The resulting 3D Cu-tripeptide framework CAS-4 (CAS: Chinese Academy of Sciences) thin film has multilevel chiral structure, [101] growth orientation and semiconductive feature with the mobility of 31 cm² V^-1 s^-1, achieving a high-performance CP visible photodetector with an anisotropy factor of 0.51, a responsivity of 0.90 A/W and a high detectivity of 1.58 × 10¹¹ Jones at 10 V under 600 nm light irradiation. In addition, by combining image sensing with convolutional neural network technology, a simple machine vision system is simulated to achieve effective and accurate enantiomer recognition. Furthermore, the CAS-4 thin film demonstrates the achievement of chiral recognition of S- and R-naproxen enantiomers through monitoring the CP visible photodetector signal. The presented finding not only develops a new type of 3D chiral semiconductive MOF thin film for chiral photoelectric applications but also provides guidance for developing high-performance circularly polarized optoelectronic devices.