Chiral Nematic Cellulose\nNanocrystal Films for Enhanced\nCharge Separation and Quantum-Confined Stark Effect

Efficient charge separation is essential in various optoelectronic\nsystems, yet it continues to pose substantial challenges. Building\nupon the recent evidence that chiral biomolecules can function as\nelectron spin filters, this study aims to extend the application of\nchirality-driven charge separation from the molecular level to the\nmesoscale and supramolecular scale. Utilizing cellulose nanocrystals\n(CNCs) derived from cellulose, the most abundant biomaterial on Earth,\nthis research leverages their self-assembly into chiral nematic structures\nand their dielectric properties. A device is introduced featuring\na chiral nematic hybrid film composed of CNCs and quantum dots (QDs),\ndecorated with iron oxide nanoparticles. Using the quantum-confined\nStark effect (QCSE) to probe charge separation, we reveal significant\nsensitivity to the circular polarization of light and the chiral nematic\nstructure of the film. This approach achieves effective, long-lasting\ncharge separation, both locally and across length scales exceeding\n1 μm, enabling potential applications such as self-assembled\ndevices that combine photovoltaic cells with electric capacitance\nas well as optical electric-field hybrid biosensors.