The Studies Of Organic Semiconductive Composites And Their Single-layered Photoreceptors

Organic photoconductive materials have become one of the high-tech materials that are needed in the modern information society. Due to the rapid development of information technology, organic photoconductive materials with high photo-responsive speed, wide photo-responsive range, high photosensitivity and low cost are required. Pristine materials evidently can't meet such requirements. It has been demonstrated that preparations of hybrid and nanoscale materials are effective ways to improve material properties, the field of which are becoming one of hot research in organic photoconductive materials at present. New phenomena and new effects can also be derived from these hybrid and nanoscale organic photoconductive materials, which can help to illuminate photocarrier generation mechanism of organic photoconductive materials.By using the composite and nanoscalization approaches, we fabricated and investigated in this thesis new kinds of organic / organic and organic / inorganic hybrid photoconductive materials and their single-layered configuration organic photoreceptors, where the charge generation material and charge transportation material display their functions, respectively, in the same layer. A series of new phenomena and new effects of these organic photoconductive materials caused by hybrid and nanoscalization are studied. Their photoconductive properties and mechanism are investigated as well. The main content are described in the following paragraphs.1. Two kinds of azo pigments with excellent photosensitivity, named as Flurenone bisazo (F-Azo) and oxazole bisazo (O-Azo), are synthesized. The preparation of organic photoconductive blended materials and their photoconductivity in single-layered photoreceptors made from F-Azo / titanium oxide phthalocyanine (TiOPc) composite and O-Azo / TiOPc, respectively, are investigated. The composites not only show excellent photo-responsive properties in the visible and near-IR region (450~850 nm), but also show complementary and synergetic enhancement effects inphotosensitivity in the visible and near-IR region. The reasons for the enhanced photoconductive properties and new effects are explained in terms of the partial and directional charge transfer from phthalocyanine to azo compound in these azo / TiOPc composites.2. The nanometer particles of O-Azo with diameters in the range of 40-60 nm and carbon nanotubes (CNTs) immobilized by nanoscale O-Azo are successfully obtained by modified liquid phase direct precipitation (LPDP). The O-Azo / CNTs nanocomposites show better photosensitivity than the bulk material in the visible and near-IR region, as well as enhancement effects in photo-response in the visible and near-IR region (470-800 nm). The main reasons for the enhanced photoconductive properties and the new effects of O-azo / CNTs nanocomposites are owing to the increase of the interface area between charge generation material and charge transportation material and the charge transfer from nanoscale O-azo to CNTs in O-azo / CNTs nanocomposites.3. The multiwalled carbon nanotube (MWCNT) bonded by 2,9,16,23-tetra amino manganese phthalocyanine (TAMnPc) was obtained and both its chemical and aggregated structures were characterized by means of FTIR, UV-Vis, TEM, and XRD. The photoconductivity of single-layered photoreceptors, where MWCNT bonded by TAMnPc (MWCNT-b-TAMnPc) served as the charge generation material (CGM), was studied by the xerographic photoinduced discharge method. The photosensitivity of MWCNT-b-TAMnPc was better than that of pristine TAMnPc and MWCNT/ TAMnPc composite obtained by simply physical blending. It is the photoinduced charge transfer from TAMnPc to MWCNT in MWCNT-b-TAMnPc that contributes to the higher photosensitivity of MWCNT-b-TAMnPc.4. New types of single-layered photoreceptors were prepared based on the above organic composite semiconductors. The best photosensitivity of TiOPc / azo composite and O-azo / CNTs nanocomposites and CNTs-b-TAMnPc composite are 0.95, 1.11 and 1.19 (lux s)-1, respectively. Furthe...