Improving Photosensitivity and Transparency in Organic Phototransistor with Blending Insulating Polymers

Organic phototransistors exhibit great promise for use in a wide range of technological applications due to their flexibility, low cost, and low-temperature processability. However, their low transparency due to visible light absorption has hindered their adoption in next-generation transparent electronics. For this reason, the present study sought to develop a highly sensitive organic phototransistor with greater transparency and significantly higher light sensitivity in the visible and UVA regions without deterioration in its electrical properties. An organic blended thin-film transistor (TFT) fabricated from the blend of an organic semiconductor and an insulating polymer demonstrated improved electrical properties in the dark and a higher current under light irradiation even though its transmittance was higher. The device exhibited a transmittance of 87.28% and a photosensitivity of 7049.96 in the visible light region that were 4.37% and 980 times higher than those of the single-semiconductor-based device. The carrier mobility of the device blended with the insulating polymer was improved and greatly amplified under light irradiation. It is believed that the insulating polymer facilitated the crystallization of the organic semiconductor, thus promoting the flow of photogenerated excitons and improving the photocurrent. Overall, the proposed TFT offers excellent low-temperature processability and has the potential to be employed in a range of transparent electronic applications.