Abstract
AbstractPolymer light‐emitting diodes based on two poly(p‐phenylene vinylene) derivatives are aged at a constant current density, leading to the formation of hole traps. Time‐resolved photoluminescence spectroscopy (TRPL) measurements show that the degraded polymer light‐emitting diodes (PLEDs) also demonstrate a decrease in exciton lifetime. The amount of nonradiative exciton quenching sites in the aged devices is quantified by Monte Carlo simulations. It is found that the number of hole traps obtained from electrical charge transport measurements matches the number of newly formed nonradiative quenching sites determined from the TRPL experiments. The results reveal the origin for the apparent different behavior of the electroluminescence and photoluminescence upon PLED degradation. The decrease of the electroluminescence is governed by recombination of free electrons with trapped holes, whereas the photoluminescence is reduced by nonradiative quenching processes between excitons and hole traps.
Highlights
In a recent study, numerical simulations on pristine and degraded PLEDs were performed to discriminate between theThe device operation of polymer light-emitting diodes (PLEDs) various proposed degradation mechanisms.[7]
It was found that has been extensively studied in the last two decades. It has been the formation of hole traps is the only mechanism consistent demonstrated that the hole transport is trap-free and space-charge with the observed increase of driving voltage and the decrease limited, whereas the electron transport is severely limited by trap- of the electroluminescence in the PLED
The knowledge that hole trap at a constant current is characterized by a decrease of the electro- formation is responsible for the increase of the PLED driving luminescence and an increase of the driving voltage.[2]
Summary
Numerical simulations on pristine and degraded PLEDs were performed to discriminate between the. Our results show that the number of generated hole traps Pt calculated from electrical measurements is equal to the concentration of nonradiative quenching sites c0 retrieved from the TRPL experiments This indicates that hole traps formed during PLED degradation quench excitons via an additional nonradiative decay process, leading to a shorter exciton lifetime. The exciton decay time and photoluminescence efficiency are governed by the diffusion of excitons toward the hole traps formed under degradation, which is a relatively slow process in PPV derivatives
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
