Solution‐phase synthesis of luminescent materials libraries

Abstract

Communications ADVANCED 2,5-DMNPAA (Table 1, Fig. 1b). However, the "improvement factor" varies with temperature due to the fact that the Tgs of the two composites are different (17 "C and 3 "C, respectively; Table 1). For a better comparison, we used the reduced temperature TR = T -Tg as a reference. In doing so, the improvement factor is constant at about 11-12, demonstrating the significant progress achieved here.A study of the temperature dependence of the shelf lifetime performed on the eutectic mixture and the composite using only 2,s-DMNPAA revealed the following regimes: i) Very long lifetimes are observed for TR < 30 K, which is attributed to the fact that, when the temperature is close to T,, the diffusional mobility of the small molecules within the polymer matrix is strongly reduced because the polymer backbone freezes and the internal free volume is reduced. ii) The shelf lifetime drops by more than one order of magnitude on going to temperatures TR > 40 K. In this regime, Arrhenius behavior i s observed in both cases, which is ascribed to thermally activated diffusion of the chromophore molecule^.^'^^ The activation energy Ea derived from our data is almost identical in both cases (Table 1). The value for pure 2,5-DMNPAA is a little higher than that for the eutectic mixture, which is probably due to its slightly higher Tg (Table 1). The most important result, however, is that the Arrhenius prefactor A is 25 times smaller for the eutectic composition than for pure 2,5-DMNPAA. As discussed above, we attribute this to the fact that for the eutectic composition the interactions between the dye molecules are the weakest for any binary mixture of the two DMNPAA isomers. The temperature-dependent studies, thus, unambiguously demonstrate the strongly reduced phase-separation tendency in the eutectic composite, yielding the best possible long-term device stability for the chromophores used.In conclusion, we obtained PR polymer devices with strongly improved shelf lifetimes by using a eutectic mixture of two isomeric EO chromophores, 2,S-DMNPAA and 3,S-DMNPAA. At this point, one can only speculate on the shelf lifetimes at room temperature, since a dramatic increase in the lifetime occurs for temperatures around Tg and below. As a matter of fact, PR devices using the eutectic composition remained clear for more than 18 months under arbitrary laboratory conditions, including peak temperatures of up to 45 "C, whereas all other devices showed at least some scattering or had even lost their transparency completely. Unlike other attempts to increase the lifetime of highly-doped organic PR devices,[82'0,"1 the PR performance of our improved devices was found to be the same as for the best materials previously known. This new concept may be extendible to mixtures of other chromophores as well.

Applications of high throughput (combinatorial) methodologies to electronic, magnetic, optical, and energy-related materials

“…A variety of other techniques have been implemented for synthesizing libraries of luminescent materials, including cosputtered CCS 181,182 and a solution-based technique using a multihead scanning ink-jet delivery system, 175 Fig. 46.…”

Combinatorial materials synthesis and high-throughput screening: An integrated materials chip approach to mapping phase diagrams and discovery and optimization of functional materials

“…In our laboratory, we also demonstrated that a multihead inkject delivery system could be used to perform automated microsynthesis of solid-state materials libraries. 15 However, for most electronic materials used in the high-tech/information industries, "thin film synthesis"-a technique with its roots in the microelectronics industry-has many advantages. A thin-film approach, "composition spread technique," has been used in the past to generate a composition-spread using off-axis codeposition.…”

Discovery and Optimization of Heterogeneous Catalysts by Using Combinatorial Chemistry

“…At present two primary methods exist for the preparation of solid-state libraries: 1) synthesis based on thin film deposition [3±6] and 2) synthesis using solution-based technologies. [7,8] These methods were then used for the discovery of superconducting, [3] magnetoresistive, [4] and luminescent [5±7, 9] materials, and electrochemical catalysts. [8] The discovery of heterogeneous catalysts is a great challenge because unlike superconductivity, magnetoresistivity, and electrochemical reactions, which can be tested by contact probes, or non-specific luminescence/fluorescence, the screening of heterogeneous catalysts requires the unambiguous detection of a specific molecule (i.e., a product) in the vicinity of small catalyst sites.…”

“…Soc. 1980 [7] The starting materials were synthesized following the route described in reference [5a]. The alkyne group was introduced by a Sonogashira coupling reaction betweeen an aryl iodide and the corresponding alkyne.…”