Doping effect of viologen on photoconductive device made of poly (p-phenylenevinylene)

Abstract

We report the photovoltaic properties of the donor-acceptor composite system of poly (p-phenylenevinylene͒ ͑PPV͒ and viologen. We observed the significant enhancement of photocurrent with increasing the doping ratio of viologen. The maximum photocurrent of viologen-doped PPV was nine times as high as that of the pristine PPV. The maximum quantum yield and photosensitivity are 13% ͑electron/photon͒ and 0.05 A/W, respectively, at low bias voltage ͑Ϫ2 V͒. The increase of photocurrent is explained with the efficient charge separation that resulted from the transfer of photoexcited electrons from PPV to viologen. The mixture of PPV and viologen can be used as a sensitive photodiode material.

A Method for Fabricating an Ultrathin Multilayer Film Composed of Poly(p‐phenylenevinylene) and Reduced Graphene Oxide on a Plastic Substrate for Flexible Optoelectronic Applications

“…The (PPV/RGO) 15 film yielded the photoresponsivity of 111.1 mA W −1 , which showed an excellent photoresponsivity compared with other carbon‐based materials (Table S2, Supporting Information). The magnitude of the photoresponsivity was twice the value obtained from a similar system comprising a blend PPV‐viologen film (50 mA W −1 ) 17. The poor performance of the PPV‐viologen photodetector was ascribed to the low rate of charge separation via photoexcited electron transfer from the PPV to the viologen groups.…”

“…The exciton diffusion length in PPV has been reported to vary between 7 and 12 nm 52, 53. Given that the thickness of a PPV layer formed using the LBL‐technique barely exceeded 1 nm, excitons generated in PPV upon photon absorption diffused and dissociated easily via the mechanism described by the Onsager theory to produce free photocarriers (electrons and holes) in the presence of an applied electric field 17…”

“…The low conductivity of pure PPV precludes its use in photoresponsive material applications. Hence, the incorporation of a conductive materials, such as fullerene C 60 or viologen is necessary to form an internal donor‐acceptor composite system 17, 18. Nonradiative charge transfer was observed in composite films composed of PPV and carbon nanotubes (CNT) 19, 20.…”

Multicolored luminescent device based on non-substituted PPV

“…PPV is insoluble and infusible, but the sulfonium salt precursor polymer is water-soluble. Park et al fabricated a photoconductive device using a composite system of PPV and viologen dibromide [10], which was prepared from a mixture of the sulfonium salt precursor polymer and viologen. However, this method can be applied for the photoconductive devices, but not favorable for devices requiring good film-forming ability and nonexistence of aggregation, namely, uniform dispersal of an additive.…”

Chemically robust conjugated polymer platform for thin-film sensors

“…We tested electron acceptors methyl viologen, ferric chloride and iodine, commonly used in conjugated polymer quenching or doping studies [21,22], as quenchers for the grafted polythiophene films. Both ferric chloride in acetonitrile (see Fig.…”