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 (EF) 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.

No abstract

Herein, an unprecedented report is presented on the incorporation of size-dependent gold nanoparticles (AuNPs) with polyvinylpyrrolidone (PVP) capping into a conventional hole transport layer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The hole transport layer blocks ion-diffusion/migration in methylammonium-lead-bromide (MAPbBr3)-based perovskite light-emitting diodes (PeLEDs) as a modified interlayer. The PVP-capped 90 nm AuNP device exhibited a seven-fold increase in efficiency (1.5%) as compared to the device without AuNPs (0.22%), where the device lifetime was also improved by 17-fold. This advancement is ascribed to the far-field scattering of AuNPs, modified work function and carrier trapping/detrapping. The improvement in device lifetime is attributed to PVP-capping of AuNPs which prevents indium diffusion into the perovskite layer and surface ion migration into PEDOT:PSS through the formation of induced electric dipole. The results also indicate that using large AuNPs (> 90 nm) reduces exciton recombination because of the trapping of excess charge carriers due to the large surface area.