Flexible 2D/0D heterojunction of bimetallic Copper molybdate and zinc sulfide quantum dots for broad-band photodetection

Abstract

Flexible photodetectors hold considerable promise for applications in imaging, communication, healthcare, and environmental monitoring. This study presents a broadband photodetector that combines a bimetallic Copper Molybdate (CuMoO₄) thin film with Zinc Sulfide Quantum Dots (ZnS QDs) on a flexible paper substrate. The ZnS QDs, synthesized through a co-precipitation technique, capitalize on their nanoscale properties, which arise from quantum confinement effects. When integrated with the CuMoO₄ thin film, these quantum dots significantly enhance the optoelectronic performance of the device. CuMoO₄, with its 1.9 eV bandgap, is highly sensitive to light in the visible and infrared regions of the spectrum. The incorporation of ZnS QDs further extends the device’s sensitivity into the ultraviolet range, enabling it to detect a broad spectrum from UV to IR within a compact configuration. The device demonstrates impressive responsivity values of 109.7 mA/W (UV), 328.44 mA/W (visible), and 33.19 mA/W (IR), along with high detectivity figures of 7.1x10¹¹ Jones (UV), 19.3 x 10¹¹ Jones (visible), and 1.9 x 10¹¹ Jones (IR) under respective light intensities of 2.9 mW/cm², 0.013 mW/cm², and 9.945 mW/cm². The combination of ZnS QDs with CuMoO₄ represents a significant breakthrough in photodetector technology, offering enhanced sensitivity, a broader spectral detection range, and the potential for integration into wearable and portable electronics.