Cyclophosphazenes offer a robust and easily modifiable platform for a diverse range of functional systems that have found applications in a wide variety of areas. Herein, for the first time, it reports an organophosphazene-based supramolecular ferroelectric [(PhCH2NH)6P3N3Me]I, [PMe]I. The compound crystallizes in the polar space group Pc and its thin-film sample exhibits remnant polarization of 5 µC cm−2. Vector piezoresponse force microscopy (PFM) measurements indicated the presence of multiaxial polarization. Subsequently, flexible composites of [PMe]I are fabricated for piezoelectric energy harvesting applications using thermoplastic polyurethane (TPU) as the matrix. The highest open-circuit voltages of 13.7 V and the maximum power density of 34.60 µW cm−2 are recorded for the poled 20 wt.% [PMe]I/TPU device. To understand the molecular origins of the high performance of [PMe]I-based mechanical energy harvesting devices, piezoelectric charge tensor values are obtained from DFT calculations of the single crystal structure. These indicate that the mechanical stress-induced distortions in the [PMe]I crystals are facilitated by the high flexibility of the layered supramolecular assembly.
Bibliographical noteKAUST Repository Item: Exported on 2023-07-26
Acknowledgements: This work was supported by SERB, India via Grant no. CRG/2019/004615 (R.B.). R.B. thanks SERB-STAR via Grant no. STR/2021/000016. T.D.A. and D.R.N. were grateful to KAUST and KSC for the financial support. P.A.C. and S.G. acknowledge the support from the Irish Centre for High-End Computing (ICHEC) and Science Foundation Ireland (12/RC/2275_P2). S.G. acknowledges support from the Science Foundation Ireland (21/PATH-S/9737) and the European Union (101039636). The views and opinions expressed were, however, those of the author only and did not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible. J.K.Z. acknowledges support from Academia Iuvenum, Wroclaw University of Science and Technology. The authors thank P. Dixit and Dr. B. Praveenkumar for poling the composite devices.
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