The Synthesis Of The Graphene Composites Counter Electrode Materials Based On Dye Sensitized Photovoltaic Devices And The Research Of Its Photovoltaic Properties

Catalytic counter electrode is an important component of dye sensitized photovoltaic device, which plays a significant part in promoting the reduction of triiodide ions by external circuit electrons, and the resultant iodide ions sustains the reduction and regeneration of oxidized dyes. The traditional Pt counter electrode owns outstanding catalytic activity and conductivity, whereas the high cost of noble metal Pt constrains the commercialization of dye sensitized photovoltaic devices. The designing of Pt free counter electrode materials with efficient charge/electrolyte ions diffusion channels and high catalytic activity is vital for the realization of low cost and efficient photovoltaic device. Due to ultrahigh specific surface area and excellent conductivity, graphene can be employed as an idea substrate for the construction of catalytic counter electrode with multi-dimensional electrons/electrolyte ions diffusion channels. In this thesis, a series of double- and ternary-component composites catalytic counter electrode materials based on graphene matrix was synthesized, and the photovoltaic performances of these materials were systematically investigated. The main contents of our work are as-follows:(1)MoS2/RGO composites counter electrode materials were synthesized by a one-step hydrothermal method, the morphology and structural features of MoS2 were tuned by the incorporation of graphene, thus enchanced the electrocatalytic activity on the redox conversion of I3-/I- mediator. Meanwhile, more efficient charge/electrolyte ions diffusion channels were established. The energy conversion efficiency of photovoltaic device based on this Mo S2/RGO composites counter electrode achieved to 6.41%, which is superior to that of device based on Pt electrode(6.28%).(2)Polyaniline was formed by in situ polymerization of monomer on the surface of amino-functionalized graphene and afforded composite via covalent bridging. The composition was optimized to increase the catalytic activity on the conversion of I-/I3- mediator. In this composite, polyaniline possesses high catalytic activity, whereas the well conductivity of graphene is beneficial for the rapid transferring of external circuit electrons to polyaniline, the synergetic effect between the two components promotes the catalytic activity of counter electrode and the charge/electrolyte ions kinetics. Amongst the composites, a-G-PANI(1:100)demonstrated the highest catalytic activity on the redox conversion of I-/I3- mediator, the energy conversion efficiency of the device based on this material is comparable to Pt based counterpart.(3)G-PANI-MoS2 ternary composite was synthesized to make full use of the catalytic activity of polyaniline and Mo S2, as well as the high surface and conductivity. It is expected to enhance the catalytic activities by virtue of employment of two catalytically active components, including polyaniline and MoS2. Both cyclic voltammetry and electrochemical impedance test evidence the well catalytic activity of the ternary G-PANI-MoS2 composite for the redox conversion of I-/I3- mediator. Photovoltaic performance of the device was improved by optimizing the composition of G-PANI-MoS2 composite, a maximal energy conversion efficiency of 5.55% was finally achieved, which is slightly higher over that of Pt counter electrode based device.