Control of charge generation and recombination in ternary polymer/polymer:fullerene photovoltaic blends using amorphous and semi-crystalline copolymers as donors

• DOI: 10.1039/c4cp01883d
• Publication Date: 2014-06-17T12:14:42Z
• Authors: Hannah Mangold; Artem A. Bakulin; Ian A. Howard; Christian Kästner; Daniel A. M. Egbe; Harald Hoppe; Frédéric Laquai
• Keywords: ddc:620; 13. Climate action; 02 engineering and technology; 540; 0210 nano-technology; 7. Clean energy; 01 natural sciences; Engineering & allied operations; info:eu-repo/classification/ddc/620; 620; 0104 chemical sciences

Charge generation and recombination processes occurring in ternary photoactive copolymer:copolymer:fullerene blends consisting of different mixing ratios between entirely amorphous semi-crystalline PPE-PPV copolymers are investigated by transient absorption pump-probe pump-push photocurrent spectroscopy. The experiments reveal that an excess polymer facilitates exciton dissociation into free charge carriers, slows down geminate recombination, suppresses non-geminate leading to increased short-circuit currents high fill factors. In contrast, utilizing solely the for their donor phase suffer from a large fraction sub-nanosecond interfacially bound charge-transfer states also fast charges, resulting significantly reduced photovoltaic performance. However, small fractions blended increase open-circuit voltage factor, while keeping parameters largely unaltered turn optimized device performance blends.