Polymer-blend thin films temperature dependence

The photophysics of jt-conjugated polymers are reviewed in detail in other chapters of this book. (See, for example, Chapter 3.) Here, we focus on the electronic and photophysical phenomena that occur at the heterojunction between two different semiconductor polymers. The heteroj unctions are formed by combining four different polyfluorene copolymers in blend or bilayer thin films and are investigated using time-resolved and steady-state, temperature- and elec-tric-field-dependent photoluminescence measurements as well as electroluminescence and time-resolved spectroscopy. We review a body of work carried out in our laboratories over the last few years, and published in numerous journal articles (see refs. [13-17]). 

A Nicolet 7000 FTIR instrument was used for the infrared studies with 120 scans accumulated for all samples. The materials used for the FTIR study were prepared as follows samples of polymers of low glass transition temperatures which were soluble in THF were prepared by the deposition of a polymer solution onto an NaCl window. For moderately high glass transition temperature polymers soluble in THF, samples were prepared by solution casting onto a glass plate. Thin films of polymer samples insoluble in THF were compression molded at 150 to 200 C (depending on the sample). An FTIR calibration curve was obtained from ethyl acrylate copolymers which had previously been neutralized completely with perchloric acid. This curve was used to determine semiquanti-tively the percent proton transfer in the blends. 

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