Efficient Photon Extraction in Top‐Emission Organic Light‐Emitting Devices Based on Ampicillin Microstructures

Abstract The desire to enhance the efficiency of organic light‐emitting devices (OLEDs) has driven to the investigation of advanced materials with fascinating properties. In this work, the efficiency of top‐emission OLEDs (TEOLEDs) is enhanced by introducing ampicillin microstructures (Amp‐MSs) with dual phases (α‐/β‐phase) that induce photoluminescence (PL) and electroluminescence (EL). Moreover, Amp‐MSs can adjust the charge balance by Fermi level ( E F ) alignment, thereby decreasing the leakage current. The decrease in the wave‐guided modes can enhance the light outcoupling through optical scattering. The resulting TEOLED demonstrates a record‐high external quantum efficiency (EQE) (maximum: 68.7% and average: 63.4% at spectroradiometer; maximum: 44.8% and average: 42.6% at integrating sphere) with a wider color gamut (118%) owing to the redshift of the spectrum by J‐aggregation. Deconvolution of the EL intensities is performed to clarify the contribution of Amp‐MSs to the device EQE enhancement (optical scattering by Amp‐MSs: 17.0%, PL by radiative energy transfer: 9.1%, and EL by J‐aggregated excitons: 4.6%). The proposed TEOLED outperforms the existing frameworks in terms of device efficiency.