Towards printed magnetic sensors based on organic diodes

We report a study of magnetotransport properties of regio‐regular poly(3‐hexyl thiophene) (RRP3HT)‐based organic diodes. The devices were fabricated using two different techniques namely spin coating and inkjet printing. Positive magnetoresistance (MR) effect was observed at room temperature in all the devices. The highest MR magnitude reached up to 16% for some spin‐coated devices and up to 10% in inkjet printed devices. The MR magnitude and line shapes were found to depend strongly on the measuring current. We observed deviation from the theoretically predicted Lorentzian or non‐Lorentzian line shape of the MR traces, which is discussed in detail in the article. Although, the printed devices exhibit MR response as high as for the spin‐coated ones, they still need to be optimised in terms of performance and yield for large scale applications as magnetic sensors.