Color-Tunable Organic Light Emitting Diodes for Deep Blue Emission by Regulating the Optical Micro-Cavity

Abstract

Nowadays, most blue organic light emitting diodes (OLEDs) are fabricated by using sky-blue emitters which are more easily synthesized when compared with other deep blue emitters. Herein, we put forward a new idea of using an optical micro-cavity based on metal electrodes to regulate electroluminance (EL) spectra of sky-blue organic light emitting diodes to obtain a saturated deep blue emission with a narrowed full-width at half-maximum (FWHM). First, we simulate micro-cavity OLEDs and find that the transmission of the anode plays an important role in the forward emission. Meanwhile, the optical path of micro-cavity OLEDs as well as the phase shifting from electrodes influence the EL spectra and induce the extra intensity enhancement. The results show that when the resonant cavity optical path is regulated by changing the thickness of emitting layer (EML) from 25 nm to 75 nm in the micro-cavity, the EL peak of blue OLEDs has a redshift from 479 nm to 493 nm with FWHM shifting from 69.8 nm to 83.2 nm, when compared to the device without the micro-cavity, whose approximate EL peak and FWHM are 487 nm and 87 nm, respectively. However, the efficiency of electroluminescence decreases in micro-cavity OLEDs. We speculate that this is on account of the ohmic contact between ITO and Ag, the surface plasma effect and the rough morphology induced by Ag electrodes.

High-efficiency top-emitting organic light-emitting diodes based on metal/ITO composite electrodes

“…The sheet resistance of Al (150 nm)/ITO (10 nm) was the best. In addition, the high carrier injection ability of anodes is crucial during the operation of TEOLEDs [28]. Table 1 also presents the carrier concentration and Hall mobility of metal and metal/ITO layers.…”

Multiplexed Optogenetics with Striped Organic LEDs

“…Optogenetics makes use of light-sensitive ion channels, known as opsins, which are genetically expressed across the cell membrane to regulate the inward and outward flux of ions in response to light of specific wavelengths. [1][2][3][4][5][6] The use of organic light-emitting diodes (OLEDs) has emerged as an alternative to the light sources that are traditionally adopted in the optogenetic practice, owing to the possibility of fabrication on flexible substrates, [7][8][9][10] operation at low voltage, [11][12][13] tunable optical properties, [14][15][16][17][18] patterning to cellular scale, [13,[19][20][21][22] and compatibility with neuroimaging techniques such as magnetic resonance imaging. [23] Furthermore, OLEDs can be stacked in order to provide emission of different colors while keeping the number of electrodes in the device minimal for implementation in small and dense architectures.…”

Tailoring Organic LEDs for Bidirectional Optogenetic Control via Dual‐Color Switching

“…Recently, organic light‐emitting diodes (OLEDs) were proposed as alternative light sources for optogenetics: [ 7–12 ] OLEDs allow for a preferable biotic‐abiotic interface owing to the possibility of fabrication on flexible substrates [ 13–18 ] and enable microsecond response times, [ 19,20 ] patterning to cellular scale, [ 21–23 ] operation at low voltage, [ 24,25 ] and tunable optical properties. [ 26,27 ]…”