Tuning the Aggregation Behaviour of BN-Coronene Diimides with the Imide Substituents and their Performance in Devices (OLED, OFET)
Résumé
Compared to perylene diimides (PDIs), the coronene diimides (CDIs), which can be viewed as a lateral core extension, show undesired effects for optoelectronic devices such as the decrease of the absorption and a hypsochromic shift. Here, we demonstrate that if the core is extended with two BN units as opposed to two CC units, the opposite is true: Large bathochromic shifts can be achieved, together with higher molar extinction coefficients and beneficial luminescence properties, e.g. a small Stokes shift and high quantum yields (lum >94%). These effects can be explained by the influence of the BN-unit onto the frontier molecular orbitals of the BNCDI. Different substitution motifs at the imide-position, cylcohexyl and 2,6-diisopropylphenyl, although they had no influence on the optical properties on a single molecule level, influenced the aggregation substantially so that the optical properties in the solid-state and the performance in organic devices (OLED and OFET) differed considerably. In combination with host matrices devices with EQE up to 1.5% and white light emission (0.317; 0.346) were obtained. The developed synthetic route starting from a regioisomeric pure 1,7substituted PDI leads to BNCDIs in good yields, which makes this class of compounds very promising.
Domaines
Chimie organique
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