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Recently, white solid-state light-emitting electrochemical cells (LECs) have drawn great attention since they exhibit advantages such as low-voltage operation, compatibility with solution processes and employing inert cathode metals. Since different correlated color temperatures (CCTs) of background illumination are necessary for various lighting applications, a real-time tunable CCT of white LECs would be highly desired in modern smart lighting systems. In this work, a widely and dynamically tuning CCT (>10000 K) of white LEC is demonstrated by employing an electrochromic device (ECD) as a real-time controllable color filter. By increasing the applied bias on the ECD to attenuate more the red parts of white EL from the white LEC, the LEC-based white light source becomes more bluish and, in consequence, shows higher CCT. This proposed LEC-based white light source with the characteristics of wide CCT range and real-time tunability is suitable for most lighting applications and modern smart lighting systems. [ABSTRACT FROM AUTHOR]

Highlights: [•] Adjust the thickness of the emissive layer of white LECs to reduce exciton quenching. [•] Recombination zone positions of white LECs are estimated by employing microcavity effect. [•] High external quantum efficiencies and power efficiencies reach ca. 11% and 20lm/W, respectively. [ABSTRACT FROM AUTHOR]

Abstract: We report efficient and color-stable white light-emitting electrochemical cells (LECs) by combining single-layered blue-emitting LECs with red-emitting color conversion layers (CCLs) on the inverse side of the glass substrate. By judicious choosing of the red-emitting dye doped in CCLs, good spectral overlap between the absorption spectrum of the red-emitting dye and the emission spectrum of the blue-emitting emissive material results in efficient energy transfer and thus sufficient down-converted red emission at low doping concentrations of the red-emitting dye in the CCLs. Low doping concentration is beneficial in reducing self-quenching of the red-emitting dye, rendering efficient red emission. Electroluminescent (EL) measurements show that the peak external quantum efficiency and the peak power efficiency of the white LECs employing red CCLs reach 5.93% and 15.34lmW−1, respectively, which are among the highest reported for white LECs. Furthermore, these devices exhibit bias-insensitive white EL spectra, which are required for practical applications, due to nondoped emissive layers. These results reveal that single-layered blue-emitting LECs combined with red-emitting CCLs are one of the potential candidates for efficient and color-stable white light-emitting devices. [Copyright &y& Elsevier]