Influence of Fullerene Ordering on the Energy of the Charge-Transfer State and Open-Circuit Voltage in Polymer:Fullerene Solar Cells

• DOI: 10.1021/jp110982m
• Publication Date: 2011-05-10T17:25:36Z
• Authors: Fortunato Piersimoni; Sylvain Chambon; Koen Vandewal; Raoul Mens; Tine Boonen; Abay Gadisa; Marta Izquierdo; Salvatore Filippone; Bart Ruttens; Jan D’Haen; Nazario Martin; Laurence Lutsen; Dirk Vanderzande; Peter Adriaensens; Jean V. Manca
• Keywords: Fullerene molecules; Systematic investigations; Side-chains; Bulk heterojunction; Charge transfer state; Functionalizations; 02 engineering and technology; Analytical techniques; Crystalline fullerene; MDMO-PPV; 7. Clean energy; Methyl esters; [SPI.MAT]Engineering Sciences [physics]/Materials; Morphological changes; Nanophases; Methanofullerenes; TEM; Electrooptical properties; 0210 nano-technology

The influence of fullerene side chain functionalization on both the morphology and electro-optical properties of bulk-heterojunction polymer:fullerene solar cells is discussed through a systematic investigation of material blends consisting of the conjugated polymer poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV) as donor and fullerene molecules with different side chains as the acceptor. The varying side chain of the fullerenes was found to induce morphological changes as confirmed by different analytical techniques such as Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), and Nuclear Magnetic Resonance (NMR). The fullerene with the shorter side chain, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), forms crystalline nanophases in the blend, while this is not the case for the alternative diphenylmethanofullerene acceptor, [6,6]-1,1-bis(4,4′-dodecyloxyphenyl)methanofullerene (DPM-12). The introduction of NMR allows us to estimate the fraction of crystalline f...