  We report the study of magnetotransport properties of regio-regular poly
(3-hexyl thiophene) based organic diodes. The devices were fabricated using two
different techniques of 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 optimized in terms of performance and yield for large
scale applications as magnetic sensors.
