Article

Poly(diketopyrrolopyrrole-terthiophene) for Ambipolar Logic and Photovoltaics

Molecular Materials and Nanosystems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Journal of the American Chemical Society (Impact Factor: 12.11). 11/2009; 131(46):16616-7. DOI: 10.1021/ja907506r
Source: PubMed

ABSTRACT

A new semiconducting polymer, PDPP3T, with alternating diketopyrrolopyrrole and terthiophene units is presented. PDPP3T has a small band gap of 1.3 eV and exhibits nearly balanced hole and electron mobilities of 0.04 and 0.01 cm(2) V(-1) s(-1), respectively, in field-effect transistors (FETs). By the combination of two identical ambipolar transistors, an inverter was constructed that exhibits a gain of approximately 30. When PDPP3T was combined with [60]PCBM or [70]PCBM in a 1:2 weight ratio, photovoltaic cells were made that provide a photoresponse up to 900 nm and an AM1.5 power conversion efficiency of 3.8 or 4.7%, respectively. In contrast to the almost constant FET mobility, the efficiency of the photovoltaic cells was found to be strongly dependent on the molecular weight of PDPP3T and the use of diiodooctane as a processing agent.

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    • "Cyclic voltammetry (CV) has been widely employed to investigate the electrochemical behavior of the molecules and estimate their HOMO and LUMO energy levels [41] [42]. As shown in Fig. 3, only oxidation potentials were recorded for the two molecules. "
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    • "This value is higher than 70% of optimal EQE of the single-junction PCDTBT:PC 70 BM solar cells (the data is not shown here), implying a high charge-collection efficiency in tandem structure.The tandem PSCs with complementary absorption spectra was further explored using small band-gap PDPP3T to replace PCDTBT in rear sub-cell. Low band-gap PDPP3T was first developed for photovoltaic application by Janssen and his coworkers[42]. Ye et al. have further boosted the performance of PDPP3T-based solar cell by using ternary-solvent strategy to tune the BHJ morphology, enabling this polymer an efficient low band-gap donor for tandem cell application[43]. "
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    • "Other people have used chloroform, a low boiling point solvent, to process PDPP3T. However, the films spin coated on the ITO substrates did not spread well due to fast evaporation of chloroform [31]. Also, people have used binary to ternary solvents [32]. "
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