Synthesis And Photoelectric Properties Of GO-rr-P3HT-CdS Ternary Heterostructurs Materials

Organic-inorganic heteroj unction solar cells have attracted wideattention by their low cost, good flexibility, and high photoelectric conversion efficiency. In this paper, the solar cells were prepared with high regioregular poly-3-hexylthiophene (rr-P3HT) as electron donor material, inorganic semiconductor as electron acceptor material and good conductivity graphene layers as electronic conductor material. The rr-P3HT was grafted to the graphene oxide (GO) by the covalent bond and the CdS was synthesized on the GO-rr-P3HT composite to get the GO-rr-P3HT-CdS ternary heteroj unction material in situ method. Moreover, the power conversion efficiency was studied by assembling the photovoltaic device based on the solution-cast GO-rr-P3HT-CdS ternary bulk heterostructure.The high regular rr-P3HT was synthesized by GRIM method using 2,5-dibromo-3-hexylthiophene as raw materials. The impact of the amount of initiator to the molecular weight, molecular distribution, and regularity was studied by FTIR, Raman, NMR characterization. The results showed that the polymer molecular weight reduced with increase of the initiator amount, also the distribution of molecular weight broadened, the regularity decreased and the ultraviolet absorption peak blue shifted.Then, the GO-rr-P3HT composite was synthesized with a acidylated graphene oxide (GO) and the CH2OH-terminated rr-P3HT which was prepared by hydroxylation reaction. The structure and performance of the as-prepared sample was studied by FTIR, XPS, and UV-spectra. The results showed that the rr-P3HT was grafed with GO successfully, and the molecular weight of the rr-P3HT had a great influence to the photoelectric performance of GO-rr-P3HT. In addition, the GO-rr-P3HT-CdS was prepared with cadmium sulphide (CdS) quantum dots in-situ doping. It was found that the size of CdS quantum dots was 4nm and the crystal form was cubic zincblende crystal by TEM、XRD characterization. Comparing with the ultraviolet absorption peak of rr-P3HT, the ultraviolet absorption peak of GO-rr-P3HT-CdS showed blue shift.Moreover, Three different bulk heterojunction photovoltaic devices were assembled with rr-P3HT/CdS, GO/rr-P3HT/CdS, and GO-rr-P3HT/CdS as the active layer material.The impact of the molecular weight of different active materials to the photoelectric performance of solar cells was studied. The results showed that the power conversion efficiency of GO-rr-P3HT-CdS solar cell increased about 223% based on the high molecule weight of rr-P3HT. The photoelectric conversion efficiency of higher molecular weigh (33855g/mol) rr-P3HT modified GO-rr-P3HT-CdS solar cell was 0.2% which is 49 times higher than the conversion efficiency of rr-P3HT/CdS solar cell. In conclusion, the graphene effectively improve the photoelectric performance of solar cells, while rr-P3HT grafting in graphene and CdS quantum dots in-situ loading improve the solar cell open circuit voltage, short circuit current and photoelectric conversion efficiency.