Solution-Processed Bio-OLEDs with a Vitamin-Derived Riboflavin Tetrabutyrate Emission Layer

Solution processed biomaterials are required for the active component to develop printed biodegradable and biocompatible optoelectronic devices. Ideal film formation is crucial for the fabrication of multilayer thin film sandwich devices. We report on the characterization of thin films of the riboflavin-derived biomaterial riboflavin tetrabutyrate and its utilization in an organic light-emitting diode. We show that the nonsolution processable precursor can form homogeneous and smooth films with the addition of tailored side groups that change its solubility. We demonstrate by grazing incidence wide-angle X-ray scattering that this chemical derivative reduces the crystallinity and enhances emission, likely by suppressing pi-pi stacking interactions. Organic light-emitting diodes with a poly(9-vinyl-carbazole)-emissive riboflavin tetrabutyrate bilayer structure yield a maximum luminance of 10 cd/m(2) and external quantum efficiency of 0.02% with a 640 nm peak orange exciplex emission. External quantum efficiency measurements of a photodiode affirm the exciplex formation.