High-on/off ratio organic photodetectors via incorporating Kaolinite

Abstract

Organic photodetectors (OPDs) have received wide attention for the weak-light signals sensitivity and promising application in imaging, and optical communication. While limited light absorption due to low carrier mobility of organic active layer. ZnO nanorods (NRs) possesses excellent photoelectric and light-trapping properties have been used in OPDs. Herein, for the first time, ZnO NRs were hydrothermal synthesized based on Kaolinite-ZnO (KAZN) seed layer. Kaolinite is a natural substance that originates from layered silicate minerals, possess unique crystal chemical properties. The KAZN NRs exhibits a smaller grain size, enhanced crystallinity and significantly enhanced light-scattering (average Haze increased 36 % from 300 to 800 nm) compared with ZnO NRs. Meanwhile, KAZN NRs have a narrower band gap, leading to superior photoelectric emission. The resulting KAZN NRs OPDs showed an enhancement in responsivity (Rs) by 44 % and achieved an impressively high On/Off ratio (18,744), representing a remarkable increase of 1800 %@ 440 nm. The noise equivalent power (NEP) has decreased by an order of magnitude at full test band. The significant improvement can be attributed to the introduction of Kaolinite, which alters the NRs crystal structure and effectively reduces OPDs dark current while enhancing photocurrent. Our research provides a simple and cost-effective approach for improving light-scattering characteristics and optoelectronic performance for ZnO based-photovoltaic devices.