Translated Abstract
As new types of photovoltaic devices, Dye Sensitized Solar Cells (DSSCs) and Perovskite Solar Cells have attracted much attention due to their low cost, simple preparation technology and high power conversion efficiency. How to effectively improve the efficiency of the new photovoltaic devices and find out the key factors of the limitation is the focus in this paper.
Dye-sensitised solar cells was developed in 1991, and the latest efficiency is as high as 13%. Compared to the traditional silicon solar cells with high cost, DSSCs has a good application prospect. However, traditional photoanode of DSSCs could not make full use of visible light region; meanwhile, the monochromatic incident photon to current conversion efficiency of the sensitizers is limited, which restricts the further development of efficiency.
In addition to this, due to the interface and surface defects, the transporting process of photon-generated carriers in photoanode is difficult, which could result in the recombination and reduce the efficiency. Specific to these problems, we design a series of metal structure/nano composites to modify the photoanode and the counter electrode, and these methods are demonstrated to improve the performance of the devices. The main contents are as follows:
Silver-loaded anatase nanotubes was designed and applied in photoanode of the DSSCs. The titanium dioxide nanotubes coud provide direct carrier transmission channel, accelerating the charge transfer and reducing the recombination; meanwhile, photoelectric properties of silver nanoparticles can effectively enhance light absorption and improve the efficiency of light capture. Thus the efficiency of the device was improved.
Plasmonic silver nanowires@TiO2 core-shell nanocomposites were designed and introduced into photoanode. This metal nanocomposite structure could prove unique dual optical-electrical channels. These characteristics provided additional optical path as well as capability of light capture, and the one-dimensional good conductive property can effectively improve the carrier collection efficiency.
Ag-encapsulated Au plasmonic nanorods were designed for enhanced dye-sensitized solar cell performance . This kind of composite structure could extend the absorption range from the visible light to red-NIR region due to its multiple resonance absorption peak features. So the modified photoanode can effectively expand the light absorption of the device and enhance the light capture efficiency of device. Meanwhile, The effective transport of the charge and the inhibition of recombination were both achieved.
A nanostructure-based counter electrode for dye-sensitized solar cells by assembly of silver nanoparticles was designed. This kind of composite electrode can utilize the light scattering property of silver nanoparticles to enhance the light re-absorption. Beyond that，large specific surface area and the effect of the hot electron injection can improve the electronic transmission characteristics at electrode/electrolyte interface. So the efficiency of the device was improved.
As for the novel perovskite solar cell, a high-efficient inverted heterojunction perovskite solar cell was demonstrated. Homogeneous and compact perovskite (CH3NH3PbI3) layer was prepared via a two-step solution deposition method. Subsequently, double-layer PCBM films were deposited by sequential spin-coating/vapor deposition process as the electron transport layer. The optimal device could achieve a 12.2% (average 11.09%) efficiency.
From the above, this article exhibits an effective combination between the nano optoelectronics and new energy development. Through modifying and controlling the solar cells at the mesoscopic scale, we can achieve the significant improvement for the performance of the device.
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