Tailoring spin mixtures in color-tunable organic electroluminescent devices
Updated: Oct 8, 2019
Xu et al. Light: Science & Applications (2018)7:46
Tailoring spin mixtures by ion-enhanced Maxwell magnetic coupling in color-tunable organic electroluminescent devices by Junwei Xu, Yue Cui, Gregory M. Smith, Peiyun Li, Chaochao Dun, Linqi Shao, Yang Guo, Hongzhi Wang, Yonghua Chen & David L. Carroll in Light: Science & Applications volume 7, Article number: 46 (2018) is a work where we show that the spin dynamics of excitons can be dramatically altered by Maxwell magnetic field coupling, together with an ion-enhanced, low-internal-splitting-energy organic semiconducting emitter.
The unique, alternating current (AC)-driven organic electroluminescent (OEL) device architecture known as a FIPEL (field induced electroluminescent lamp) optimizes this magnetic field coupling allowing nearly complete control over the singlet-to-triplet ratio (from fluorescent to phosphorescent emission in a single device).
Spin population control is attributed to magnetically sensitive polaron–spin pair intersystem crossings (ISCs). These can be directly manipulated through external driving conditions.
This approach to spin-tailoring is demonstrated in the work. Specifically we build a simple hybrid (double-layer) fluorescence–phosphorescence (F–P) device using a polyfluorene-based emitter with a strong external Zeeman effect and ion-induced long carrier diffusion. Remarkably fine control over de-excitation pathways is achieved by controlling the device-driving frequency (and thus the internal magnetic field strength), resulting in complete emission blue–red color tunability. Picosecond photoluminescence (PL) spectroscopy directly confirms that this color control derives from the magnetic manipulation of the singlet-to-triplet ratios.
On our way to spintronic lighting devices?
It is hoped that these preliminary results may pave the way to far more exotic organic devices that utilize magnetic-field-coupled organic systems. Such systems are poised to usher in an era of dynamic spintronics at room temperature