Efficient bulk heterojunction solar cells based on a low-bandgap polyfluorene copolymers and fullerene derivatives

Abstract

A low-bandgap polymer (PF-PThCVPTZ) consisted of fluorene and phenothiazine was designed and synthesized. With the donor-acceptor segment, the partial charge transfer can be built in the polymer backbone leading to a wide absorbance. The absorption spectrum of PF-PThCVPTZ exhibits a peak at 510 nm and an absorption onset at 645 nm in the visible range. As blended with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as an electron acceptor, narrow bandgap PF-PThCVPTZ as electron donor shows significant solar cell performance. Under AM 1.5 G, 100 mA/cm(2) illumination, a power conversion efficiency (PCE) of 1.85% was recorded, with a short circuit current (J(SC)) of 5.37 mA/cm(2), an open circuit voltage (V(OC)) of 0.80 V, and a fill factor (FF) of 43.0%. (C) 2009 Elsevier B.V. All rights reserved.