Ultrasensitive Hydrogen Detection via Layered n-Type Polymer Chemiresistors

Hydrogen is a promising clean fuel source, but its flammability necessitates highly sensitive sensors to detect leaks before they pose an explosion risk. Chemiresistors are simple, commercially available devices but struggle to achieve parts per billion detection at room temperature. We address this challenge using a new composite device structure that leverages n-type conjugated polymers as effective semiconductors for ultrasensitive hydrogen detection. To achieve a large response and rapid kinetics, we develop a layered architecture where the polymer sits between an electron-rich PdPt layer and an electron-deficient metal oxide layer. By decoupling doping and dedoping to two spatially separated metal layers, we achieve a >4000% response to 0.5% H₂ in dry air and a limit of detection of 174 ppb. The devices also exhibit good humidity tolerance, retaining sub-parts per million sensitivity under ambient conditions. This approach enables exceptional hydrogen sensing performance using simple, inexpensive, and commercially viable fabrication methods.