Enhancement of photovoltaic performance using hybrid CdS nanorods and MEH-PPV active layer in ITO/TiO 2/MEH-PPV:CdS/Au devices

Abstract

Polymer-based solar cells offer many advantages for cell fabrication such as low-cost roll-to-roll production, large area and flexibility. In this study, the effect of blending cadmium sulfide (CdS) nanorods in poly(2-methoxy-5-(2′-ethylhexyloxy)- p-phenylene vinylene) (MEH-PPV) active layer of ITO/TiO 2/MEH-PPV/Au heterojunction devices on the photovoltaic performance was investigated. The ITO/TiO 2/MEH-PPV:CdS blend/Au solar cells were fabricated using nano-porous titanium dioxide (TiO 2) layer infiltrated with a blend of the MEH-PPV and CdS nanorods to form an active layer for the solar cells. The MEH-PPV layer is known to be an electron donor and a hole transport material. Schottky diode ITO/MEH-PPV/Al devices have a limited power conversion efficiency so the modified ITO/TiO 2/MEH-PPV:CdS blend/Au ohmic heterojunction devices were fabricated. Improvement of photocurrent density, fill factor and power conversion efficiency were demonstrated. These improvements were expected to be a result of a more stable depletion region at the TiO 2/MEH-PPV interface. Moreover the mixing of the CdS nanorods in the MEH-PPV layer improved electron transport in the conjugated polymer MEH-PPV film areas that were disconnected between the conjugated polymer and the TiO 2 film.