Investigation On The Electrode Materials Of Dye-sensitized Solar Cell

Dye-sensitized solar cells (DSSCs), third generation of solar cells, have the promising future. In the past two decades, dye-sensitized solar cells have been succeeded help with the TiO2photoanode and nobel Pt counter electrodes. However, the high cost and low photo to electron conversion efficiency (PCE) have been demonstrated to be "bottleneck." for large-scale production. The pure TiO2nanocrystalline film is still faced with major difficulties such as high interface recombination and low availability ratio of light. Pt-based counter electrode electrocatalysts are susceptible to the corrosive by the redox species of electrolyte and high-temperature heat treatment of environment. Furthermore, Pt belongs to the most precious natural resources on earth. Therefore, it is necessary to develop new electrode materials for DSSCs, design new type structure of DSSCs, synthetize high performance semiconductor for photoanode and counter electrode. On the other hand, it is very important to explore new approach for dramatically enhance PCE and low cost manufacture.In this work, we investigated on the photoanode and photocathode materials of DSSCs and applied those materials in DSSCs. It is very important for obtaining a new route with a low cost and a large-scale production to fabricate dye-sensitized solar cells. We assembled and studied a series of DSSCs with the photoanode of SnO2or α-Fe2O3and photocathode of PANI-RGO or MWCNTs-PANI. Furthermore, we also investigated on the scattering effect and electron transfer of hierarchical structure materials.The morphology and microstructure of the samples were examined by FESEM, TEM, AFM, and surface profilometer. The spectroscopic measurements including XRD、Raman、FTIR、XPS、 UV-Vis spectroscopy were performed to study the optical properties, structure feature, and components presented. The photovoltaic performance, electron transfer, interface dynamics of as-prepared DSSCs was characterized by I-V、IPCE、EIS、IMVS/IMPS et al..We present here the results of our current efforts on:1. We developed two multifunctionalized hierarchical SnO2and α-Fe2O3nanoflower structure which were used in high-efficiency dye-sensitized solar cells via hydrothermal method. Those modified film fabrication allowed the agglutination of the hierarchical nanoflower with each other by3D necking during the film formation, thus greatly enhancing the inter-nanoflower connectivity, facilitating electron transport. The new multifunctionalized hierarchical structured nanoflower was used as efficient photoanode in the DSSCs application because of its efficient light scattering ability and longer electron lifetime compared to the commercial P25-TiO2nanoparticles. In all the samples, a reasonable performance of hierarchical structured nanoflower SnO2-TiCl4(100) DSSCs has been obtained with up to5.60%power conversion efficiency. The superior light scattering effect, long electron lifetimes and slower electron recombination are together responsible for the higher Jsc and η of cell SnO2-TiCl4(100).2. We demonstrated a facile synthesis of a reduced graphene oxide-polyaniline (PANI-RGO) and a carbon nanotubes-polyaniline (MWCNTs/PAN1) nanocomposite film as the photocathode of DSSC by a in-situ co-polymerization of aniline monome in a solution of perchloric acid under low temperature. The DSSCs assembled with the photocathode of PANI-RGO and MWCNTs/PANI were investigated in this work. The PANI-RGO nanocomposite has the hierarchical pore structure and high specific surface area as well as the PANl-RGO nanocomposite counter electrode has higher electrocatalytic activity and good conductivity. We designed a new type of efficient DSSCs which photoanode composed of nano-flower structured hematite (a-Fe2O3) and a photocathode composite made of reduced graphene oxide-polyaniline (PANI-RGO). It is found that a-Fe2O3nanoflower structure exhibits favorable energy conversion efficiency. The as-prepared MWCNTs/PANI nanocomposite with axle-sleeve structures, followed by a spin-coating and thermal treatment in N2atmosphere procedure to obtain a uniform layer on the conductive substrate which is used for DSSCs. This method has versatile operability and can be easily deposited on any type of substrates. The MWCNTs/PANI nanocomposite film shows dramatic improvement in the mechanical, thermal, electrical and redox catalytic properties compared to those of single component counter electron materials, followed is used for DSSCs. The MWCNTs/PANI composites exhibited power-conversion efficiency(η) of-7.2%, comparable to η of the screen-printed Pt (7.6%). The synthesis approach presents a promising research route for a cost-effective design of CNTs-conducting polymers nanocomposite as CEs for DSSCs.