Using magneto-electroluminescence to analyze the influence of high temperature environment on exciton evolution processes in organic light-emitting diodes
Abstract
<p indent="0mm">An organic light-emitting diode (OLED) based on rubrene was fabricated, and the magneto-electroluminescence (MEL) was used to analyze the exciton evolutions in the device under high temperature environment. The MEL characteristics of the device in the high and low applied magnetic fields indicate that the exciton evolution at room temperature is dominated by singlet exciton splitting (STT) processes, <sc>420 K</sc> ambient temperature the STT process weakens, but the exciton evolution process of intersystem crossing (ISC) occurs. Combined with the surface morphology, luminescence-current characteristics, current efficiency and spectrum of the device, we believe that the high temperature environment causes a large number of structure defect in the rubrene film. The defect limits the diffusion of the polaron pairs and excitons inside the device, and improves the conversion efficiency between the singlet polaron pairs and triplet polaron pairs, and results in an ISC process that is not conducive to internal quantum efficiency in high temperature. The capture of excitons inhibits the conversion of singlet excitons to triplet excitons, resulting in a weakening of the STT process in high temperature environments, thereby increasing the quantum efficiency of the device. It not only deepens the understanding of the influence of high temperature environment on the exciton evolution process in rubrene type OLED devices, but also provides a technical solution to monitor the structural changes of devices by using organic luminescence magnetic effect.</p>
