Polymer-Based White-Light-Emitting Electrochemical Cells with Very High Color-Rendering Index Based on Blue-Green Fluorescent Polyfluorenes and Red-Phosphorescent Iridium Complexes.

Application of the concept of three-color (red (R), green (G), and blue (B)) light-mixing to obtain white light is the most suitable way to realize white-light-emitting devices with very high color-rendering indices (CRI). White-light-emitting devices based on the three-color-mixing method could be used to create lighting and display technologies. Here, white-light-emitting electrochemical cells (LECs) with very high CRIs are reported, which were fabricated by using blend films composed of a fluorescent π-conjugated polymer (FCP), poly(9,9-dioctylfluorene-co-benzothiadiazole) (PFBT), and a phosphorescent iridium complex, [Ir(ppy) (biq)] (PF ) (where (ppy) =2-phenylpyridinate and biq=2,2'-biquinoline).

Fabrication of White Light-emitting Electrochemical Cells with Stable Emission from Exciplexes.

The authors present an approach for fabricating stable white light emission from polymer light-emitting electrochemical cells (PLECs) having an active layer which consists of blue-fluorescent poly(9,9-di-n-dodecylfluorenyl-2,7-diyl) (PFD) and π-conjugated triphenylamine molecules. This white light emission originates from exciplexes formed between PFD and amines in electronically excited states. A device containing PFD, 4,4',4''-tris[2-naphthyl(phenyl)amino]triphenylamine (2-TNATA), Poly(ethylene oxide) and K2CF3SO3 showed white light emission with Commission internationale de l'éclairage (CIE) coordinates of (0.

Theoretical investigation of the excited states of coumarin dyes for dye-sensitized solar cells.

Using time-dependent density functional theory (TD-DFT), configuration interaction single (CIS) method, and approximate coupled cluster singles and doubles (CC2) method, we investigated the absorption spectra of coumarin derivative dyes (C343, NKX-2388, NKX-2311, NKX-2586, and NKX-2677), which have been synthesized for efficient dye-sensitized solar cells. The CC2 calculations are found in good agreement with the experimental results except for the smallest coumarin dye (C343). TD-DFT underestimates the vertical excitation energy of the larger coumarin dyes (NKX-2586 and -2677).