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Conductivity dopants are used in organic light-emitting devices (OLEDs) to reduce the operating voltage and consequently improve the power efficiency. Here, we report the synthesis, as well as photophysical and electroluminescent properties, of an organic molecular p-type conductivity dopant: 1,3,4,5,7,8-hexafluorotetracyanonaphthoquinodimethane (F6-TNAP). F6-TNAP was obtained in a three-step two-pot synthesis from commercially available octafluoronaphthalene. When 1%-5% of F6-TNAP was coevaporated with N,N 0 -di-1-naphthyl-N,N 0 -diphenyl-1,1 0 -biphenyl-4,4 0 diamine (R-NPD) an absorption band at 950 nm was formed, which is attributed to charge transfer and assigned to the F6-TNAP radical anion. Single-carrier (hole-only) devices fabricated with F6-TNAP doped into R-NPD as the hole transport layer (HTL) show a >2 V decrease in operating voltage, compared to the undoped device. A decrease in operating voltage was also demonstrated in blue OLED devices using a F6-TNAP-doped HTL, with only a slight decrease in external quantum efficiency, thus resulting in a net improvement in power efficiency. These results demonstrate that F6-TNAP may be useful in generating high-efficiency OLEDs.

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Natural gas purifications using chemically selective hydrogen sulfide (H 2 S) sorbents could be more efficient if chemical selectivity for H 2 S could be maintained without thermal regeneration of the sorbent. We used tertiary alkanolamines to reversibly capture H 2 S in the absence of water to produce hydrosulfide-based ionic liquids in high yield. These alkanolammonium hydrosulfide ionic liquids release H 2 S by exposure to inert gas or by mild heating. H 2 S can be rapidly and nearly quantitatively released at ambient temperature from the alkanolammonium hydrosulfide ionic liquids by the addition of nonpolar antisolvents, some of which naturally phase separate from the spent alkanolamine. The antisolvent-induced regeneration of the alkanolamine potentially allows an efficient H 2 S gas scrubbing process that is chemically selective and can be operated continuously at or near ambient temperature.

Systems comprising multiple sorbent and catalytic beds have been developed for the warm cleanup of coal- and biomass-derived syngas. Tailored specifically for biomass application, the process described here consists of six primary unit operations: (1) a Na2CO3 bed for HCl removal, (2) two regenerable ZnO beds in parallel for bulk H2S removal, (3) a ZnO bed for H2S polishing, (4) a NiCu/SBA-16 sorbent for trace metal (e.g., AsH3) removal, (5) a steam reforming catalyst bed for tars and light hydrocarbon reformation and NH3 decomposition, and (6) a Cu-based LT-WGS catalyst bed. Simulated biomass-derived syngas containing possible inorganic contaminants (H2S, AsH3, HCl, and NH3) and hydrocarbons (methane, ethylene, benzene, and naphthalene) was used to demonstrate process effectiveness. The efficiency of the process was demonstrated for a period of 175 h, during which time no signs of deactivation were observed. However, postrun analysis revealed that small levels of sulfur slipped through the sorbent bed train to the two downstream catalytic beds. Future improvements will be made to the trace metal polishing sorbent to ensure complete inorganic contaminant removal (to low parts per billion level) prior to the catalytic steps. However, dual regenerating ZnO beds were effective for continuous removal for the vast majority of the sulfur present in the feed gas. The process was effective for complete AsH3 and HCl removal. The steam reforming catalyst completely reformed all the hydrocarbons present in the feed (methane, ethylene, benzene, and naphthalene) to additional syngas. However, postrun evaluation, under kinetically controlled conditions, indicates some deactivation of the steam reforming catalyst occurred. Spent catalyst characterization suggests this can be attributed, in part, to coke formation, likely due to the presence of benzene and/or naphthalene in the feed. Future adaptation of this technology may require dual, regenerable steam reformers. The process and materials described in this report hold promise for the warm cleanup of a variety of contaminant species within warm syngas.

We report the synthesis and characterization of 2-(3-(adamantan-1-yl)propyl)-3,5,6-trifluoro-7,7,8,8tetracyanoquinodimethane (F3TCNQ-Ad1), a substituted analog of 2, 3,5,7,8,8tetracyanoquinodimethane (F4TCNQ), designed for p-type conductivity doping. The dopant is designed as a model for substituted alternatives to F4TCNQ that maintain similar electronic properties with the goal of engineering dopants with superior fabrication characteristics over F4TCNQ. We describe the design strategy for F3TCNQ-Ad1 based on molecular modeling predictions that substitution of a single fluorine atom of F4TCNQ has little effect on the electronic properties of the molecule. Photophysical and electrochemical characterization reveal that the adamantyl substituent in F3TCNQ-Ad1 does not significantly alter the electronic properties of the substituted dopant relative to F4TCNQ. Unfortunately, F3TCNQ-Ad1 degrades under standard sublimation conditions, preventing sublimation deposition processing. Instead, hole-only devices were made via solution-processing of the p-doped films with the structure glass/ITO/2.3 Â 10 3 Å PVK:(MTDATA:dopant)/2.0 Â 10 2 Å Au/1.0 Â 10 3 Å Al, where dopant is either F4TCNQ or F3TCNQ-Ad1. We demonstrate that F3TCNQ-Ad1 increased the conductivity of the films by at least 1000 times compared to an undoped device.

We studied the influence of a pyridine moiety versus a phenyl moiety when introduced in the molecular design of an ambipolar host. These pyridine-based host materials for organic light-emitting diodes (OLEDs) were synthesized in three to five steps from commercially available starting materials. The isomeric hosts have similar HOMO/LUMO energies; however, data from OLEDs fabricated using the above host materials demonstrate that small structural modification of the host results in significant changes in its carrier-transporting characteristics.