Liquid Water Molecular Connected Quantum Dots for Self-Driven Photodetector

Abstract

The interactions between solid quantum dots (QDs) are weak as the excitons in QDs are difficult to be dissolved into electrons and holes, which limits the performance of QDs based photodetector. Herein, through putting QDs inside the water, it is intriguingly found that excitons are dissolved into electrons and holes by the interaction between QDs and water molecules, which further contribute to the formation of long-range electron/hole transport channels within the water. At zero voltage bias, a transient photo-polarized current is repeatedly produced, the specific responsivity and detectivity of liquid-based photodetector with molybdenum disulfide (MoS₂) QDs aqueous suspension can reach 188.1 mA W⁻¹ and 1.164 × 10¹⁰ Jones with 820 nm illumination, respectively. The specific spectra of photodetectors can be promoted by selected QDs with different absorption peaks. Actually, the responsivity of liquid-based photodetector with cadmium selenide (CdSe) QDs exhibits the most significant enhancement effect at the peak of exciton absorption wavelength of QDs, as much more excitons in QDs can be dissolved into electrons and holes. It is anticipated that the ability to dissolve excitons in QDs and form conducting channels by dynamic construction of water molecules will bring possibilities for high-performance optoelectronic devices across a wide range of application scenarios.