Electrostatic Layer-by-Layer Assembly of CdSe Nanorod/Polymer Nanocomposite Thin Films

Electrostatic layer-by-layer assembly was the basis for the synthesis of multilayer nanorod/polymer composite films. Cationic and water-soluble CdSe nanorods (NRs) were synthesized and partnered with anionic polymers including poly(sodium 4-styrenesulfonate) (PSS) and two polythiophene-based photoactive polymers, sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate (PTEBS) and poly[3-(potassium-6-hexanoace)thiophene-2,5-diyl] (P3KHT). Controlled multilayer growth is shown through UV-vis spectroscopy, cross-sectional SEM and surface analytical techniques including atomic force microscopy. The formation of an intimate nanorod/conducting polymer bulk heterojunction is confirmed through cross-sectional SEM, TEM, and scanning Auger analysis. A series of photovoltaic devices was fabricated on ITO electrodes using CdSe NRs in combination with PTEBS or P3KHT. A thorough device analysis showed that performance was limited by low short circuit current although charge transfer was confirmed in the ELBL nanocomposite thin films.