Device‐dependent angular luminance enhancement and optical responses of organic light‐emitting devices with a microlens‐array film

Abstract— By taking the organic emitter apodization calculated from electromagnetic theory as input, the angular luminance enhancement of organic light‐emitting devices (OLEDs) with a microlens‐array film (MAF) can be further evaluated by the ray‐tracing approach. First, the OLEDs of different Alq³ thickness are fabricated and their angular luminance measurements are compared to simulation results. Second, mode analyses for different layers are performed to estimate the enhancement potential of the MAF‐attached devices. Finally, by decreasing the Alq³ thickness, increasing the viewing angle, and attaching the MAF, the EL spectral peak shifts of the OLEDs seem irregular, but the spectral blue shifts induced by the optical structures are all explained by the optical responses (EL spectra divided by the intrinsic PL spectrum). In conclusion, the organic emitters with higher off‐axis‐angle luminous intensity cause lower out‐coupling efficiency but gain higher enhancement after the MAF is attached. With the choices of apodizations and microstructures, the tailored or customized angular radiation patterns can be also made possible.