Exploiting Supramolecular Assemblies for Filterless Ultra-Narrowband Organic Photodetectors with Inkjet Fabrication Capability
Narrowband photodetectors are useful for myriad applications involving color discrimination as well as biological imaging and machine vision. Prevalent devices use broadband light absorbing materials in conjunction with electric (charge collection narrowing, photo multiplication) and optical strategies (optical cavity) to narrow down the spectral response of the detector. Here we exploit the intrinsic narrow absorption width of ~13-50 nm peculiar to J-aggregates of strongly coupled cyanine dye molecules for narrowband photodetectors. Albeit using ultrathin J-aggregate films (10 nm) the unparalleled optical aggregate properties lead to high external quantum efficiency (15 %) and response speed (15 kHz) at low bias voltage (-1 V). We show that the self-assembly process and device architecture used permit to incorporate J-aggregates of various cyanine dyes with photodetection maxima ranging from the visible to the near-infrared region up to 1000 nm. Narrow bandwidth (< 50 nm) photodetectors fabricated by inkjet printing the active device layers including the J-aggregate film perform on par with spin-coated devices, thus underlining their industrial potential.