Improving the photo-current of poly(3-hexylthiophene): [6,6]-phenyl C71 butyric acid methyl-ester photodetector by incorporating the small molecules

Abstract

This work demonstrates the improvement in photo-current response of poly(3-hexylthiophene) (P3HT)-based thin film organic photodetector by introducing [6,6]-phenyl C71 butyric acid methyl-ester (PC71BM) as an acceptor in binary blended thin films and vanadyl 3,10,17,24-tetra-tert-butyl-1,8,15,22-tetrakis(dimethylamino)-29H,31H-phthalocyanine (VTP) as a complementary holes’ component in ternary blended thin films. The combination of these materials creates favorable energy levels that facilitates the transport of charge carriers from one material to another until it reaches at the respective electrodes. The increase in optical absorption across broader spectral range, the increase in interfacial area and the enhancement in electrical parameters were observed and discussed. In this study, device with ternary P3HT:PC71BM:VTP blended thin films with ratio of 1:1:1 shown the best photo-current response (at 1 V), in which the increase in short-circuit photocurrent density (Jsc) (6.0 mA/cm2) is 78% higher than that of P3HT:PC71BM:VTP with ratio of 1:1:2. The Jsc of ternary blended thin film device (1:1:1) is 5 times higher than that of single material device and it appeared to be 58% higher than that of binary P3HT:PC71BM devices. The increase electrical parameters indicated a significant enhancement in photo-current with the introduction of ternary blended thin films organic photodetector that constitutes of well-matched materials based on their individual optical, morphological and electrical properties.