| Popis: |
In recent years, the world storage of coal, oil, natural gas, and other sources of nonrenewable energy is becoming less and less, meanwhile the problem of energy shortage is becoming more and more emergent which will restrict the development of the international economy. Under this background, most countries begin to develop solar energy, which promotes the development of solar cells. As we know, solar cells can straightforwardly transform light into electricity through the photovoltaic effect, and currently silicon solar cell is the most sophisticated technology in commercialization. Nevertheless, because of the complexity of the fabrication technique and the high cost of silicon materials, it is not easy to cut its price substantially. Therefore, finding new materials and new methods to fabricate economic solar cells is necessary. Right now, the hot research topic in this field is perovskite solar cells (PSCs). This kind of solar cell has a special light-absorbing active layer, which is called organic inorganic hybrid perovskite (OIHP), the most common is methylammonium lead iodide (CH3NH3PbI3 or MAPbI3). This kind of PSC can be easily solution-processed, and the raw materials are less expensive, both make it cheap to process and simple to fabricate. Previous studies have shown that perovskite like MAPbI3 with a three-dimensional (3D) structure are highly efficient. But the poor stability limits its application. Thus, it is urgent to develop a novel kind of PSCs with both high efficiency and good stability. Here, we present two feasible methods, compositional engineering and interfacial engineering, to fabricate 2D:3D mixed PSCs and 2D/3D bilayer PSCs for achieving the goal of high-performance photovoltaics. In the first method, with the help of 4-fluoro-phenethylammonium (4F-PEA) organic spacer, the corresponding champion PSC can obtain a better device performance with a power convention efficiency (PCE) over 20%, as well as a better stability for 3000 hours with less than 40% loss in PCE at a relative humidity of 10%-15%. This novel 2D:3D mixed [(4F-PEA)2MAn-1PbnI3n+1]x:MAPbI3 perovskite will provide an innovative method to fabricate high-performance PSCs with good stability. In the second method, the surface defect passivation of MAPbI3 perovskite films with binary organic spacer 3-phenyl-2-propen-1-amine/4-fluoro-phenethylammonium (PPA/4F-PEA) is reported. We found that a 2D layer (PPA)(4F-PEA)MAn-1PbnI3n+1 can be formed on the surface of MAPbI3 perovskite and achieve more efficient PSCs by reducing defects and inhibiting non-radiative recombination. The results show that the PCE of this kind of PSCs can reach above 20%. In addition, a open-circuit voltage (VOC) up to 1.16 V can be obtained with the presence of the top 2D layer, which is 93% of Shockley-Queisser limit VOC (1.25 V). Because of the hydrophobic nature of the top 2D layer, the optimized PSCs can maintain 97% of the initial PCE after 500 hours at a relative humidity of 10%-15%. The unique idea of the 2D layer as a moisture-proof protection window, maintaining efficient 3D perovskite structure provides clues for the development of high-performance perovskites and paves the way for the wide application of efficient and stable PSCs shortly. |
