The durability and failure cause of a polymer Schottky diode made with PEDOT : PSS-pentacene were investigated. A polymer Schottky diode was fabricated by dissolving pentacene in N-methylpyrrolidone (NMP) and mixing with PEDOT : PSS. Pentacene solution having a maximum concentration of approximately 9.7 mmoles was prepared by simply stirring the solution at room temperature for 36 h. As the pentacene concentration increased, the absorption of the broad UV regime increased dramatically. However, absorption peaks of pentacene at 301 and 260 nm were not observed for the PEDOT : PSS-pentacene. A three-layered polymer Schottky diode was fabricated and its current–voltage (I–V) characteristic was evaluated. The current was reduced by 7% in the first 50 min and then stabilized during biased electrical field sweeps. After 500 and 800 min, catastrophic failure occurred. FESEM images revealed that the electrode damage caused catastrophic failure of the Schottky diode.

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Biodegradable honeycomb patterns are useful for a cell culture substrate and tissue engineering. Attaining control over pore size and depth is extremely important for many biological and optical applications. In this study, uniform sizes and various heights of cellulose acetate (CA) honeycomb patterns were fabricated using a photoresist micro-mould. The carbonyl peak was diminished by 60%, 90% and 98% after 1 h, 4 h and 7 h of deacetylation (DA) reaction, respectively, and disappeared after 31 h of DA reaction. The UV–visible transmittance decreased as the DA reaction time increased up to 17 h and increased after 60 h reaction. The transmittance reduction was due to the rough structure of the surface and the inside of the pattern created during the early DA reaction. The rough structure became dense and smooth as the reaction time further increased. This may be a result of uniform removal of the acetyl group at the surface and inside the film after enough time of DA reaction. The line width was increased by 39% and 56% after 1.5 h and 17 h DA reaction, respectively. The line width returned to the initial width after further DA reaction. These results imply that the structure of the CA mould became rough in the early stage of the DA reaction and became dense and smooth after further DA reaction.

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