Charge Transfer in Nanowire-Embedded PEDOT:PSS and Planar Heterojunction Solar Cells

Hybrid metallic nanowire-embedded, highly conductive poly(3,4-ethylenedioxy thiophene):polystyrenesulfonate (PEDOT:PSS) with synergetic properties is indispensable for enhancing the performances of conductive polymer-based electronic devices. Here, we report embedment of silver nanowires (AgNWs), with diameter ∼100 nm and a high concentration (500 mg/mL) of nanowires dispersed in either ethanol or isopropanol, in PEDOT:PSS and compare the effects of the nanowire-dispersing solvents as well as its thicker diameter and high concentration on the overall properties and particularly its charge transfer characteristics and planar heterojunction solar cell (HSC) properties. Furthermore, electrostatic force microscopy is applied to elucidate the direct charge transfer from AgNWs to the PEDOT:PSS matrix. The AgNW-embedded PEDOT:PSS-based planar HSCs show a very high open-circuit voltage of over 638 mV and a high power conversion efficiency greater than 15.3% and without any significant influence from the AgNW dispersing solvents. While charge transfer in PEDOT:PSS without AgNWs occurs through the conducting PEDOT grains, enhanced charge transfer is realized in AgNW-embedded PEDOT:PSS with charge transport from PEDOT grains to AgNWs and then to PEDOT grains before reaching the top electrode in the HSC. The AgNW-embedded PEDOT:PSS hybrid materials pave a simple way to enhance the charge transfer performance in not only HSCs but also other hybrid or heterojunction electronics.