Filtering and Assembly of Si Nanocrystals/Conjugated Polymer Blend with Reduced Oxygen Penetration

Abstract

Colloidal silicon nanocrystals (Si-ncs) blended with a conjugated poly(methoxy-ethylexyloxy-phenylenevinilene) (MEH-PPV) polymer offer great potential for the development of environment-friendly optoelectronic and photovoltaic devices with a bulk-heterojunction structure. To achieve efficient performance of the bulk heterojunction, both the size distribution and mesoscopic ordering of Si-ncs in the conjugated polymer need to be improved. In this respect, a capillary induced filtering (CIF) and an assembly of Si-ncs/MEH-PPV blends in nanoporous anodic alumina membranes are demonstrated. We showed that the CIF through the nanoporous anodic alumina membranes is a low cost, room-temperature procedure to improve both the Si-nc distribution and morphology of the Si-ncs/MEH-PPV composites. The CIF and narrowing of the Si-nc size distribution within the polymer matrix result in a reduced penetration of oxygen into the filtered blend. Furthermore, the alumina membrane can serve as a template for the formation of Si-ncs/MEH-PPV nanofiber-like composites, which are controlled by an opened alumina membrane thickness. Such a low temperature approach could serve as a concept for the formation of thicker and more efficient devices based on a fiberlike bulk heterojunction at low cost.