Improved out-coupling efficiency of organic light-emitting diodes using micro-sized perovskite crystalline template

Abstract

In this study, we demonstrated that the out-coupling efficiency of organic light-emitting didoes (OLEDs) is enhanced using external light extraction film obtained from the CH 3 NH 3 PbBr 3 (MAPbBr 3 ) perovskite template. We found that the perovskite crystalline is very suitable to be used as a template because by changing the process conditions such as the solvent type, its micro-scale crystal growth can be achieved. In addition, the perovskite template can be used repeatably, allowing multiple films to be imprinted on one template. By attaching the imprinted polydimethylsiloxane (PDMS) films on the bottom-emitting OLED, we found that the light-emitting performances are improved. The surface morphology of the perovskite template as well as the imprinted PDMS light extraction film were investigated with an optical microscope and a scanning electron microscope (SEM). OLEDs equipped with PDMS light extraction films imprinted on 20 wt% and 30 wt% MAPbBr 3 templates show improved external quantum efficiency by about 30.9% and 11.1%, respectively. It is demonstrated that the transmittance and haze characteristics of films are not significantly changed by imprinting from templates with different concentrations. Rather, the improvement in the out-coupling efficiency of the OLEDs is largely attributed to the fill factor of the crystals of the film and not the light scattering effect from the film. We demonstrated that the out-coupling efficiency of organic light-emitting didoes (OLEDs) is enhanced using external light extraction film obtained from the CH3NH3PbBr3 (MAPbBr3) perovskite template. We found that the perovskite crystalline is very suitable to be used as a template because by changing the process conditions such as the solvent type, its micro-scale crystal growth can be achieved. In addition, the perovskite template can be used repeatably, allowing multiple films to be imprinted on one template. By attaching the imprinted polydimethylsiloxane (PDMS) films on the bottom-emitting OLED, we found that the light-emitting performances are improved. The surface morphology of the perovskite template as well as the imprinted PDMS light extraction film were investigated with an optical microscope and a scanning electron microscope (SEM). OLEDs equipped with PDMS light extraction films imprinted on 20 wt% and 30 wt% MAPbBr3 templates show improved external quantum efficiency by about 30.9% and 11.1%, respectively. It is demonstrated that the transmittance and haze characteristics of films are not significantly changed by imprinting from templates with different concentrations. Rather, the fill factor is reduced when the PDMS light extraction film is imprinted on templates with high concentration. Thus, the improvement in the out-coupling efficiency of the OLEDs is largely attributed to the fill factor of the crystals of the film and not the light scattering effect from the film. The low-cost, and simple fabrication process for the light extraction films pave the way for commercial application in advance OLEDs. • External light-extraction film is obtained with perovskite template. • Micro-scale crystal template is prepared and PDMS is imprinted. • The EQE enhancement of 30.9% is demonstrated. • Fill factor of template is investigated.