Fabrication of Ag Nanorods-Embedded P3HT/PCBM Films for the Enhancement of Light Absorption

Abstract

We report a facile method for preparing hybrid nanostructured films composed of poly(3-hexlythiophene) (P3HT) and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) with silver (Ag) nanorods (AgNRs) array. The AgNRs were synthesized by an electrochemical deposition method using an anodic aluminum oxide template with 50-nm-pore-diameter and 10-μm-thickness. The nanostructured P3HT/PCBM film was formed by the intercalation of AgNRs into the P3HT/PCBM film. The nanostructured P3HT/PCBM film with AgNRs showed enhanced optical absorption in the spectral range of 300-650 nm due to localized surface plasmon resonance and scattering effects around the AgNRs compared with spin-coated and nanopatterned P3HT/PCBM films without AgNRs. The design and manipulation of conjugated polymers have been extensively studied in basic science and for a wide range of applications. 1Conjugated polymers have many advantages, such as low production cost, high flexibility, and controllable conductivity, over inorganic materials.2 In addition, the chemical and physical properties of conjugated polymers can be improved by controlling their molecular weight and structure. 3,4 Due to these advantages and the applicability of conjugated polymers, many efforts have been dedicated to the design of chemical structures with specific functionalities, 5 efficient methodologies for synthesis processes, 6 and a suitable structure for optoelectronic applications. 4,7,8 Importantly, one key method for improving the efficiency of photovoltaic devices is to enhance the optical absorption in the organic active layers of these devices. Recent extensive studies on optoelectronic devices have shown that hybrid, nanostructured materials can give rise to remarkably improved energy conversion efficiency via various light-trapping mechanisms and optical absorption enhancement schemes. Moreover, the efficiency of optoelectronic devices largely depends on the structural design of these devices because the incorporation of nanostructures into polymer films offer advantages, such as adjustable material thickness, 1 controllable interfaces, 8 and large surface area, 9 compared to the bulk structure in polymer films. Therefore, many types of nanostructures, including nanoparticles, nanowires, nanotubes, and tetrapods, have been fabricated, and their effectiveness in improving photovoltaic performance has been examined using hybrid material systems. [10][11][12] In particular, the use of a porous template to prepare nanostructures is a promising method that has the advantages of highly regular pore arrays and the ability to control aspects of template geometry, such as pore diameter, pore depth, and inter-pore distance.13 Thus, the design and modification of the surface morphology of polymers using a highly ordered porous template can play an important role in improving efficiency and reducing the production cost of optoelectronic devices, such as organic light-emitting diodes (OLEDs) and organic solar cells. 14,15 Recently, metallic nanostructures have been explored to ...