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An efficient white polymer light-emitting diode (WPLED) with stable Commission Internationale de l’éclairage (CIE) coordinates is fabricated. A blue electroluminescence (EL)-emitting conducting polymer [poly(9,9-di- n-hexyl-fluorenyl-2,7-diyl)] is used as a host for red [ Bis(1-phenyl-isoquinoline)(acetylacetonate)iridium(III)] and green [iridium(III) tris(2-(4-tolyl)pyridinato- N,C2)] phosphorescent dyes. Although efficient triplet energy transfer is not possible in the green phosphorescent dye, the self-trapping mechanism is utilized for the emission of EL in the green region while an efficient triplet exciton energy transfer from the host to the red dye is utilized for EL in the red wavelength region. Concentrations of the three constituents are optimized to obtain pure white light of appropriate CIE coordinates. An efficient electron-blocking layer based on a biomaterial (salmon-DNA) is also incorporated in the WPLED to improve the device performance. The WPLED shows three distinguished peaks for the primary colors and achieved a maximum luminance and luminous efficiency of 350 cd/m2 and 0.86 cd/A, respectively. [ABSTRACT FROM AUTHOR]

Optical properties of Zn(II) complex using 1,2-bis(8-hydoxyquinolin-2-yl)ethane (Zn(BQOEH)), such as optical absorption, photoluminescence, and electroluminescence, are studied. Zn complex film emits a yellow photoluminescence band centered at 564 nm and an electroluminescence band at 567 nm. Transient characteristic of the organic light-emitting devices (OLEDs) with Zn(BQOEH) as the emitting material are demonstrated. An optical pulse of more than 5 MHz is obtained from the OLED with Zn(BQOEH) [ABSTRACT FROM PUBLISHER]

Abstract: The effect of salmon DNA–CTMA as an electron blocking layer (EBL) has been examined on the performance of MEH–PPV and PFO-based light emitting diodes. Though the turn-on voltage increases with incorporation of EBL, a significant increase in luminance and luminous efficiency for both the devices is observed. The EBL improves the device performance by blocking electrons at the EBL–polymer interface, thereby increasing the recombination probability of electrons and holes. The luminance of the MEH–PPV based Bio-LED increases to 100cd/m2 from 30cd/m2 while a corresponding increase for the PFO based LED is to 160cd/m2 from 80cd/m2 with and without EBL, respectively. [Copyright &y& Elsevier]

Abstract: It has been found that insertion of a thin Ba buffer layer between the Al electrode and the MEH-PPV layer results in a significantly higher current density in ITO/MEH-PPV/Al polymer light-emitting diodes due to a reduction of the potential barrier at the cathode–polymer interface. The photoluminescence is found to increase with the addition of porphyrin-containing platinum as the central atom, showing that some of the triplet excitons decay radiatively as a result of mixing porphyrin. [Copyright &y& Elsevier]