Synthesis Of Polyaniline/Metal Oxide Semiconductor Based Photosensitive Nanomaterials And Design Of Their Photoelectronic Device

Semiconductor nanomaterial has wide application prospects in various photoelectronicfunctional devices such as photodetectors, photoswitches and solar cells owing to itsdistinctive and outstanding photoelectric characteristics. To explore and develop newphotosensitive semiconductor materials, to design and fabricate new photoelectric deviceshave attracted a great deal of research interest. This dissertation focused on conductingpolyaniline and metal oxide semiconductor nanomaterials. The optimal semiconductornanomaterials and their composites were prepared by solid-state reaction, hydrothermalmethod, interfacial polymerization, electrospinning technique, and the photosensitive propertyof them was investigated and discussed. Using the P-N junction between N-type metal oxideand P-type polyaniline, the N-P-N structural photodetectors were designed and the mainachievements were summarized as follows:1. We present a facile synthesis of manganese oxide （MnO₂） nanocomposite with ultraviolet（UV） photosensitive characteristic by a solid-state reaction based on the reduction ofpotassium permanganate （KMnO4） by aniline, which provides a new family and moreselectivity for UV photosensitive nanomaterials in the future. The UV photosensitivemechanism are attributed that the energy level of polyaniline lie in the band gap of the MnO₂and serve as a bridge to transport the photogenerated electrons in MnO₂, then more electronscan be transport from vanlence band to conductor band in MnO₂.2. We have developed a method, surface-functionalization with well-matched energy level,to induce ultraviolet （UV） or visible （Vis） photoresponse of semiconductor material film fromnot only weak to strong but also nothing to something. By this way, UV and Visphotoresponses of two metal oxides, Bi₂O₃and V₂O₅, have been realized for the first time byfunctionalizing them with polyaniline （PANI）.3. We demonstrate a relatively independent UV photodetector which is composed of onelayer of p-type PANI nanowires and two layers of n-type ZnO nanorods. Different to otherUV photoelectronic nanodevices, it doesn’t need any external power source except UV lightwhen it works. High photocurrent (¹.4×10^-5A) and photosensitivity （>10⁵）, defined as（Iphoto-Idark）/Idark, at zero bias have been obtained, which can be attributed to the design of thetwo opposite p–n heterojunctions in the UV photodetectors.4. We have designed and fabricated a novel photodetector that is composed ofsandwich-structured n-type zinc oxide nanorods arrays, p-type polyaniline thin film, anddye-modified n-type ZnO nanorods arrays. When the photodetector is alternatively illuminated by ultraviolet and visible light from the same direction, it outputs alternatingcurrent.5. The TiO₂/polyaniline （PANI） core-shell nanofibers with unique ultraviolet photoresponse（UV） were designed and fabricated. When the core-shell nanofibers were performed in nooxygen （O₂） and full of O₂environment under UV illumination respectively, the increase anddecrease of photoconduction were observed. The mechanism of the opposite photocurrentresponse of the core-shell materials was investigated in detail, which indicated that thedecrease of the photoconduction in O₂was caused by the increasement of the thickness for thedepletion zone.