Porous materials are ubiquitous in nature and have found a wide range of applications because of their unique absorption, optical, mechanical, and catalytic properties. Large surface-area-to-volume ratio is deemed a key factor contributing to their catalytic properties. Here, it is shown that introducing tunable nanopores (50–700 nm) to organic semiconductor thin films enhances their reactivity with volatile organic compounds by up to an order of magnitude, while the surface-area-to-volume ratio is almost unchanged. Mechanistic investigations show that nanopores grant direct access to the highly reactive sites otherwise buried in the conductive channel of the transistor. The high reactivity of nanoporous organic field-effect transistors leads to unprecedented ultrasensitive, ultrafast, selective chemical sensing below the 1 ppb level on a hundred millisecond time scale, enabling a wide range of health and environmental applications. Flexible sensor chip for monitoring breath ammonia is further demonstrated; this is a potential biomarker for chronic kidney disease.
A generic method to solution process nanoporous thin films with pore sizes tunable from 50 to 700 nm for both the polymer and small molecule is demonstrated. The nanoporous transistors fabricated exhibit highly sensitive detection of volatile markers below 1 ppb on a hundred millisecond time scale. The nanopores function by exposing reactive sites in the conductive channel to the analytes.