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New electroluminescent materials based on chelate zinc complexes

“…14 The film containing 0.5% NR in Zn(OBBA) 2 is charac terized by a PL band in the red spectral region with a maximum at 625 nm, which is related to the transfer of an electron excitation energy from Zn(OBBA) 2 molecules to NR molecules. 11, 12 The electroluminescence devices prepared by the above described procedure emit a visible light when an electric voltage is fed directly. The electroluminescence spectra are close to the photoluminescence spectra.…”

“…11 Samples for measuring absorption and pho toluminescence spectra were prepared as films deposited on a quartz support by the same method as those for electrolumines cence devices. IR spectra were measured for KBr pellets on a Perkin-Elmer Spectrum BX FTIR spectrometer.…”

“…The emitting layer, being a solid solution of NR in Zn(OBBA) 2 , was deposited only on PTA from a solution con taining NR and Zn(OBBA) 2 in the corresponding ratios. 11 The preparation of the device was completed by vacuum sputtering of a metallic cathode of Al or a Mg-Ag alloy (10 : 1 wt/wt). Procedures in vacuo were carried out at a basic pressure of 5•10 -6 Torr.…”

A Comparison of Crystalline- and Graft Polymer-Based Chemosensors

“…For a Dexter process, quenching decays linearly as the acceptor concentration decreases. Alternatively, quenching decays nonlinearly for a Förster mechanism . For the system reported here, a plot of Q versus the acceptor concentration ratio is linear, indicating that exciton migration via the Dexter mechanism is more prevalent than Förster migration, Figure .…”

“…However, reports by a number of groups using flexible conjugated polymers also show high sensitivity in solution, implying that intrachain hopping may be more important. − If exciton-hopping is the major mechanism, a rigid conjugated polymer is unnecessary. For example, it has been known for at least 70 years that excitons within crystalline and graft polymer films diffuse between 450 and 1350 Å, hopping between molecules 1500−40 000 times. − The efficient hopping within crystalline and graft copolymer films makes these materials attractive alternatives to conjugated polymers.…”