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Thienopyrazine-based low-bandgap polymers for flexible polymer solar cells
Published online by Cambridge University Press: 02 September 2010
Abstract
The optical gaps of the low-bandgap PPVs (PM-20, PM-19, PM-18) are decreased down to 1.6-1.7 eV compared with that of MDMO-PPV (2.2 eV). The best lateral hole mobility was determined to be 2.1 × 10-3 cm2/V s (PM-18) in field effect transistors and exceeds that of MDMO-PPV (poly-[ 2-methoxy-5-(3'.7'-dimethyloctyloxy)-1.4-phenylenevinylene], 8.5 × 10-4 cm2/V s). This allows to reduce the PCBM ([6.6]-phenyl-C $_{61(71)}$ -butanoic acid methyl ester) content in solar cell devices down to 1:2 w/w giving a better $\eta_{\rm AM1.5}$ than for MDMO-PPV:[60]-PCBM cells (PM-19:[60]-PCBM 2.32% on ITO-PET, 2.86% on ITO glass). The charge transfer to PCBM as acceptor occurs quite normally and shows an effective charge separation using light-induced spin resonance spectroscopy (LESR). The [70]-PCBM $^{-\bullet}$ signals are shifted to lower field related to those of [60]-PCBM $^{-\bullet}$ and overlap more with the polaron signal of PM-19. The LESR g-factor components of [70]-PCBM $^{-\bullet}$ are reported for the first time. The external quantum efficiency peak values achieve up to 42% at ~350–400 nm and 26% at ~640 nm (PM-19:[60]-PCBM).
- Type
- Research Article
- Information
- The European Physical Journal - Applied Physics , Volume 51 , Issue 3: Focus on Flexible Organic Electronics , September 2010 , 33204
- Copyright
- © EDP Sciences, 2010
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