Self-Powered Multivariable Organic Photovoltaic Sensors for Accurate Volatile Organic Compound Discrimination

Most existing VOC sensors rely on battery power and only single-parameter outputs, limiting long-term deployment, maintenance efficiency, and chemical discrimination. Here, we report a self-powered multivariable photovoltaic sensor (MPVS) that repurposes an organic photovoltaic junction as an information-rich VOC sensing platform. By integrating a gas-permeable silver nanowire electrode with a donor-acceptor bulk-heterojunction active layer, the MPVS enables efficient analyte access while maintaining stable photovoltaic operation under illumination. Exposure to VOCs induces coupled and reversible changes in open-circuit voltage (VOC) and short-circuit current density (JSC), providing two orthogonal sensing features without external power input. Using a single PM6:Y6 junction, we demonstrate concentration-dependent responses and reliable discrimination of representative VOCs. Extending the concept to a five-element MPVS array incorporating different Y-series acceptors generates high-dimensional photovoltaic fingerprints that enable accurate identification of eight chemically distinct VOCs. Density functional theory (DFT) calculations and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) reveal that analyte-dependent noncovalent interactions, particularly strong hydrogen bonding in the case of formic acid, underlie the observed selectivity. By integrating energy harvesting and multivariate sensing within a single organic photovoltaic platform, this work establishes a scalable, battery-free approach to artificial olfaction, offering a promising pathway for distributed and long-term VOC monitoring systems.