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

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. © 2020 Elsevier B.V.