Synthesis And Photoelectric Properties Of CdS/P3HT/CNT Heterostructures

Hybrid solar cells consisting of organic materials and inorganic materials have attracted a growing interest. Poly (3-hexylthiophene)(P3HT) turn into the most promising donor material, due to its ease of synthesizing and the unique design flexibility; the use of carbon nanotube (CNT) as acceptor materials is just started on, as a one-dimensional structure material, CNTs can improve the performance of materials by forming network throughout the whole system; CdS nanocrystal particles (CdS) are equipped with their broad-range spectral absorption and high electron mobility. Although previous works have shown a variety of dualistic-structure materials combined by two arbitrary materials of P3HT, CNTs and CdS nanocrystal particles, there are few reports for the preparation of P3HT-CNT-CdS ternary-structure heterostructure material. In this paper, we report the preparation of P3HT/CNT/CdS ternary-structure heterostructure material, which combine advantages of three materials and solve the problems such as the low carrier mobility of P3HT and aggregation of CNT or CdS.Firstly, we modified the CNT by acidification, chloridization and grafting with3TE monomers respectively under the best conditions with the purpose of introducing the thiophene ring onto the surface of CNT, so that the P3HT can be grafted to the CNT covalently. Then we charactenszed the change of structure by IR spectrometry and Raman spectrometry.Then,3HT monomers were reacted with modified CNT directly by the method of "grafting from", and ultimately growing into the long chain from the surface of CNT, so P3HT grafted CNTs (P3HT-g-CNT) were obtained. in this section, we also discussed the influence of acidification, the amount of oxidant and the proportion of mixed solvent, by changing the amount of oxidant and the proportion of mixed solvent, the coating thicknesses of P3HT grafted on the surface of CNTs can be controlled. TEM, Raman etc. were used to study the morphology and structure of P3HT-g-CNT; in the meantime, it was proved that the connection type between P3HT and CNT is covalent bond.On the basis of P3HT-g-CNT, S precursors and Cd precursors were added directly to generate CdS nanocrystalline on the surface of P3HT-g-CNT, according to the difference of S precursors and Cd precursors, we synthesized CdS/P3HT/CNT in four different systems, and studied their morphology respectively, then we found that the CdS/P3HT/CNT with the best morphology were synthesized in the precipitated sulfur and cadmium nitrate system, so we detailed studied the morphology and structure of three products in this system with different ratio of S:Cd:KBH4,the size of the CdS of three products are>20nm>10～20nm,10～15nm respectively. The structure of products were studied by Raman spectrometry and XRD, moreover, XRD results indicated that CdS nanocrystalline are of cubic zinc blende structure.Finally, we studied the photoelectric property of P3HT-g-CNT and CdS/P3HT/CNT, such as optical property, electrical property, and energy level matching, moreover, photovoltaic devices was assembled by taking P3HT-g-CNT and CdS/P3HT/CNT as the active material, then we discussed the morphology and photovoltaic conversion of the photovoltaic devices and found the photoelectric property of P3HT-g-CNT and CdS/P3HT/CNT is excellent and conform to our imagine in the beginning.