Efficient, stable and high color rendering index white polymer light-emitting diodes by restraining the electron trapping

Abstract

Superior solid-state light source should possess not only a high device efficiency but also high color rendering index (CRI) and excellent color stability. Here, we obtained efficient, stable and high CRI white polymer light-emitting diodes (WPLEDs) through applying the well-chosen trichromatic polymers and restraining the electron trapping. The trichromatic polymers all possess the similar mainchain units, their EL spectra shows an equidistant distribution. Detailed studies revealed that the part of green and red emission in the WPLED derive from the electron trapping which led to the current-dependent spectra. Applied proper electron transporting layer can enhance the direct electron injection which resulted in the electron trapping being restrained and improving the color stability. The optimized WPLED got a LEmax of 10.17 cd A 1 and CRI of 92, the CIE coordinates (0.346, 0.345) almost keep the same with the operating current density increasing from 10.53 mA cm 2 to 263.16 mA cm 2 .

Solution-processed single-emissive-layer WOLEDs with high efficiency and ultra-high color rendering index beyond 90

“…The performance of the three-color WOLED with 1 wt% Au-7 , to the best of our knowledge, is one of the best results among the reported single-EML SP-WOLEDs with CRI > 90 (Table S3, ESI†). 5 Even when compared with vacuum-deposited multiple-EML WOLEDs having CRI above 90, the EQE max achieved by this SP-WOLED is among the best values (Table S4, ESI†). 12…”

“…The integration of three or more emission colors is effective to construct SP-WOLEDs with CRI ≥ 90 by covering the entire visible range. 5 For example, Bradley et al developed a panel of blue-, green-, and red-emitting polymers featuring electroluminescence (EL) located at 455 nm, 535 nm, and 620 nm, respectively. 5 a Benefiting from the broad EL spectra of green- and red-emitting polymers, the three-color WOLED achieved Commission International de l’Éclairage (CIE) coordinates of (0.36, 0.37) and CRI of 91.…”

“…Despite high-quality white electroluminescence being achieved, the device efficiencies of single-EML SP-WOLEDs reported so far are still significantly lower than those of vacuum-deposited WOLEDs. 1 g ,4 h ,5…”

Photophysical and Electro-Optical Properties of Copolymers Bearing Blue and Red Chromophores for Single-Layer White OLEDs

“…More specifically, in Fluorescence Energy Transfer (FET) process, an excited fluorophore (host) transfers its energy to an adjacent molecule (guest) by dipole-dipole interaction. Guest-host systems are also attractive materials for investigating energy-migration processes [10][11][12][13][14][15][16][17][18]. There are two types of FET processes, which are dependent on the copolymer chain architecture, host/guest strength and composition.…”

Benzodithiophene‐S,S‐tetraoxide (BDTT) as an Acceptor Towards Donor‐Acceptor (D‐A)‐Type Semiconducting Electropolymers

“…Recent developments in conducting polymers have enabled their use in diverse industrial applications such as lithium-ion batteries, [1] organic photovoltaics, [2] organic field-effect transistors (OFET), [3] and NIR polymer probes. [4,5] In part, the donoracceptor (D-A) design is an effective strategy to tune the optical band gap of a material. Such molecular designs can influence the bandgap difference between electron-rich donors and electron-poor acceptors, with the development of new acceptor moieties affecting the most change in regards to the optical properties.…”