Highly Efficient Green Sensitive OPT Using Solution Processed PBTTT-C14 Thin Films by Optimized Thermal Annealing

Abstract

Here, we report the fabrication of solution processible PBTTT-C14 thin films with high molecular orientation and uniformity using a technique known as unidirectional floating film transfer method (U-FTM) for developing highly efficient organic phototransistors (OPT) for green light sensing. U- FTM fabricated PBTTT-C14 films were transferred onto octadecyl trichlorosilane (OTS) modified Si/ SiO2 substrates and annealed at different temperatures. The influence of annealing temperature on the crystallinity of PBTTT-C14 thin films have been analyzed systematically. Under the optimized condition, maximum progression in optical anisotropy and high-order crystallinity were observed in the PBTTT-C14 film. The anisotropic charge transport characteristic offered by U- FTM fabricated PBTTT-C14 film resulted in high field effect mobility in the fabricated OPTs. Under dark conditions, the device showed a charge carrier mobility of 3.57�10-1 cm2/ V. s and an on/off ratio of 5.2�104. Achieved a high responsivity of 2638 A/W, photosensitivity of 4.6�103 and specific detectivity of 2.5�1014 Jones under the illumination of monochromatic green light (525 nm). This work emphasis the affordable fabrication of highly efficient photodetectors for modern green light sensing applications. � 1980-2012 IEEE.