A High‐Resolution Thin‐Film Fingerprint Sensor Using a Printed Organic Photodetector

Abstract Organic photodetectors (OPDs) have attracted much attention in recent years, due to their promise in large‐area light sensing applications. Here, high‐resolution slot‐die‐coated large‐area bulk heterojunction organic photodiode (OPD) arrays are reported. The OPD uses a novel electron transport layer, indium gallium zinc oxide in combination with a molybdenum oxide top‐electrode. Together, these effectively reduce dark current densities to very low levels of ≈10⁻⁷ mA cm⁻² at −2 V. The OPDs show linear behavior in a wide range of light intensities and high detectivity values under reverse bias conditions. When coated on a 508 ppi TFT backplane, a high‐quality optical fingerprint scanner capable of imaging in reflection is realized. The optical and electrical properties of the fingerprint sensor are characterized and high‐resolution fingerprint images are obtained.