On the Response Speed of Narrowband Organic Optical Upconversion Devices

Abstract Organic upconversion devices (OUCs) consist of an organic infrared photodetector and visible light‐emitting diode (OLED), connected in series. OUCs convert photons from the to are use applications such as process control or imaging. Many require a fast OUC response speed, namely ability accurately detect rapidly changing signal. Here, high image‐contrast, narrowband reported that near‐infrared (NIR) light at 980 976 nm with full‐width half maximum 130 into light. Transient photocurrent measurements show speed decreases when lowering NIR intensity. This is contrary conventional photodetectors opposite speed‐versus‐light trend. It further found increases (when using phosphorescent OLED) (for fluorescent increasing driving voltage. To understand these surprising results, analysis by numerical simulation conducted. Results behavior primarily determined electron mobility OLED. proposed low drift velocity emitter layer sets fundamental limit OUCs.