Transient effects of polymer-organic light emitting diodes and their impact on individual identification friend/foe

Abstract

The Individual Identification Friend/Foe (IIFF) patch is a unique system designed to prevent shooter-on-shooter fratricide in a battlefield environment. Using a Polymer-Organic Light Emitting Diode (p-OLED) as the emitter for the IIFF system provides many unique opportunities and challenges in system design. Both high overall brightness in the Infrared (700-900 nm) region and fast turn-on time (e.g., the time it takes from application of bias voltage to full intensity of the emitter) are important for the IIFF system to be successful. In this thesis six p-OLED candidates are tested for potential use in the IIFF device. The best candidate was determined to be a mixture of two different ink formulations (4:1; Yellow:Red) combined with an updated cathode design. This provided a 410% increase in brightness and faster turn-on compared to the original Covion Yellow emitter in the Infrared. This thesis also includes initial research on material properties of the p-OLED that determine the key factors that went into material selection. P-OLEDs differ from inorganic semiconductors in that the p-n junction is created after a bias voltage is applied and the width of the p-i-n regions varies with the bias voltage applied to the material. Two distinct transient effects during turn-on are determined, and the turn-on intensity as a function of time is able to be modeled as an exponential rise-to-maximum function with two exponential time constants, one on the order of 1 s and the other on the order of 10 s.