Dimmable sunlight-like organic light emitting diodes with ultra-high color rendering index

Abstract

We propose novel dimmable sunlight-like white organic light-emitting diodes that were fabricated using three luminophores to form an emitting spectrum similar to black body radiation at 2250K with ultra-high color rendering index (CRI) value of 91, which nearly remained the constant at various luminance values ranging from 100 to more than 2500cd/m2 at Commission Internationale de l’Eclairage chromaticity coordinates of (0.51,0.41). Introducing charge modification layers suppressed the energy transfer between the emitting material layers and increased the probability of carrier recombination. Moreover, we reveal that covering long-wavelength ranges played a vital role in achieving high CRI values; the CRI values of a spectrum artificially shifted toward a long-wavelength direction (from 610 to 620nm) remained constant, whereas those of a spectrum shifted toward a short-wavelength direction (from 610 to 600nm) dropped to 79.