862260-63-7Relevant academic research and scientific papers
Novel anthracene materials for applications in lithography and reversible photoswitching by light and air
Fudickar, Werner,Linker, Torsten
, p. 4421 - 4428 (2010)
Herein we demonstrate how the photoreaction between anthracenes and singlet oxygen (1O2) is employed for applications either as photoswitch or as photoresist. Thin films of the diaryl-alkyl anthracene 1 and the analogous oligomeric species 2 were irradiated under photomasks to generate pattern structures composed of 1/1-O2 and 2/2-O2. Kelvin probe force microscopy (KPFM) provided a powerful and nondestructive method to image the pattern information. The following studies based on AFM, KPFM and contact angle measurements unfold that the two species 1 and 2 underwent different progressions after the imaging step. Degrading is observed for the monomeric compound 1 and the pattern eventually becomes recognizable in topography. In the oxidized state (1-O2) the monomeric species remains physically stable. In consequence, the unreacted portion is removable and the remaining oxygenated form 1-O2 is sufficiently stable to protect an underlying substrate (e.g., silver) from etching. Thus, the system 1/1-O2 operates as photoresist. On the other hand, both states of the oligomer 2 remain stable. The film is stable up to temperatures >120 °C required to erase the pattern within acceptable time by cycloreversion. Anthracene 2 therefore acts as erasable and rewritable photochromic switch. The different behavior between 1 and 2 is explained by phase transitions which cause crystallization and finally ablation. Such transitions affect only the monomeric system 1/1-O2 and not the oligomeric system 2/2-O 2. In conclusion, we designed two very similar materials based on diarylanthracenes, which can act either as a photoresist or as a rewritable photochromic switch.
Imaging by sensitized oxygenations of photochromic anthracene films: Examination of effects that improve performance and reversibility
Fudickar, Werner,Linker, Torsten
, p. 9276 - 9283 (2007/10/03)
The aliphatic anthracene compound 1 and the oligomeric anthracene 2 were synthesized. Thin films of 1 and 2 mixed with the sensitizers tetraphenylporphyrin (TPP) and methylene blue (MB) were irradiated with visible light in air. Upon formation of singlet oxygen, the anthracene units were converted quantitatively to the corresponding endoperoxides. Heating of the irradiated samples afforded the parent anthracenes with high yields. Here, we demonstrate that the kinetics and reversibility of this reaction strongly depend on the microenvironment of the anthracene groups in the two compounds. The photooxidation of thin films of 1 is accompanied by interesting changes in the morphology of the film and allows the first application of 1 as a nondestructive negative-tone photoresist for lithography and as an oxidizing ink. The morphology of 2 remained unchanged after photooxidation as a result of the stabilizing oligomer back-bone. This stabilizing effect significantly improves the photochromic performance of 2. The reversibility of the photooxidation is very high (> 90%) for oligomeric films of 2 after several cycles of irradiation and heating. Decomposition of the anthracene and a loss of the activity of the sensitizer diminish slightly the performance of the monomeric species.
Reversible light and air-driven lithography by singlet oxygen
Fudickar, Werner,Fery, Andreas,Linker, Torsten
, p. 9386 - 9387 (2007/10/03)
Monolayers and thin films of diphenylanthracene react in the presence of a singlet oxygen sensitizer by irradiation on air to the corresponding endoperoxides and reconvert to the starting compounds upon heating. This reaction has been applied to create 2D fluorescent pattern structures. Motifs which are written by this technique can be erased and replaced by new images. Copyright
