Controlling the excited electronic states in luminescent systems remains a challenge in the development of fluorescent and phosphorescent dyes. Now, scientists in Japan have developed a unique organic fluorophore that changes its emission color without loss of efficiency when externally stimulated. The study published in the journal Angewandte Chemie explains this behavior by a simple phase transformation of the solid substance, which could be relevant for optoelectronic applications such as in smart OLEDs.
Although luminescence is an extensively studied phenomenon and its theoretical basis is well understood, the development of new pigments and dyes with outstanding functionality is not straightforward. Phase transitions of a solid material may quench the fluorescence, and pigments in OLED applications are prone to aging. Now, the research group of Takuma Yasuda at Kyushu University, Fukuoka, Japan, has synthesized a green emitting pigment that responds to external stimuli by a remarkable color change into orange emission, and that without no observed loss in luminescence efficiency. This two-color behavior of one pigment might by highly useful for the development of smart optoelectronic and sensor systems.
To obtain efficient luminescent systems, scientists are increasingly focusing on the excited states and the electronic transitions: The more distinct and
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