Nanostructured p-n junctions for kinetic-to-electrical energy conversion

J. Briscoe, M. Stewart, Melvin Vopson, M. Cain, P. Weaver, S. Dunn

    Research output: Contribution to journalArticlepeer-review


    Piezoelectric ZnO nanorods grown on a flexible substrate are combined with the p-type semiconducting polymer PEDOT:PSS to produce a p-n junction device that successfully demonstrates kinetic-to-electrical energy conversion. Both the voltage and current output of the devices are measured to be in the range of 10 mV and 10 μA cm−2. Combining these figures for the best device gives a maximum possible power density of 0.4 mW cm−3. Systematic testing of the devices is performed showing that the voltage output increases linearly with applied stress, and is reduced significantly by illumination with super-band gap light. This provides strong evidence that the voltage output results from piezoelectric effects in the ZnO. The behavior of the devices is explained by considering the time-dependent changes in band structure resulting from the straining of a piezoelectric material within a p-n junction. It is shown that the rate of screening of the depolarisation field determines the power output of a piezoelectric energy harvesting device. This model is consistent with the behavior of a number of previous devices utilising the piezoelectric effect in ZnO.
    Original languageEnglish
    Pages (from-to)1261-1268
    Number of pages8
    JournalAdvanced Energy Materials
    Issue number10
    Publication statusPublished - 2012


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