Organic field-effect transistor-based sensors: recent progress, challenges and future outlook

OFET-based sensors consisting of small molecules or polymers as an active layer have garnered significant attention in recent years owing to their high flexibility and sensitivity, low fabrication cost and excellent substrate conformity. Compared to their inorganic counterparts, organic materials hold a rich family of functional moieties that can selectively react or bind with analytes as specific sensing sites. This review highlights recent progress (2018-2024) in the fabrication of OFET-based gas, pressure, temperature, light, pH, humidity, chemical and biological sensors with sensitivities approaching the limits of detection at parts per billion molar concentration. The challenges that are considered a bottleneck in developing sensors that fully meet the requirements for practical applications and the solutions proposed to tackle these challenges have also been included. The optimizations of the OFET devices for sensing activity, including the modification of semiconducting layers, dielectric engineering, and electrodes and their interfaces, are also illustrated. Furthermore, their relationships with sensing parameters, such as sensitivity, selectivity, and response time, as well as the proposed sensing mechanisms are discussed. This review is expected to offer inspiration for the future design of OFET-based sensors with diverse device architectures, as it features the current progress in the design and development of the extended-gate-type OFETs, electrolyte-gated OFETs, polyelectrolyte-gated OFETs, dual-gate OFETs and water-gated OFETs.